electrical resistivity experiment

school Campus Bookshelves
menu_book Bookshelves
perm_media Learning Objects
login Login
how_to_reg Request Instructor Account
hub Instructor Commons

Margin Size

Download Page (PDF)
Download Full Book (PDF)
Periodic Table
Physics Constants
Scientific Calculator
Reference & Cite
Tools expand_more
Readability

selected template will load here

This action is not available.

9.4: Resistivity and Resistance

Last updated
Save as PDF
Page ID 4402

$ \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } $

$ \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} $

$ \newcommand{\id}{\mathrm{id}}$ $ \newcommand{\Span}{\mathrm{span}}$

( \newcommand{\kernel}{\mathrm{null}\,}\) $ \newcommand{\range}{\mathrm{range}\,}$

$ \newcommand{\RealPart}{\mathrm{Re}}$ $ \newcommand{\ImaginaryPart}{\mathrm{Im}}$

$ \newcommand{\Argument}{\mathrm{Arg}}$ $ \newcommand{\norm}[1]{\| #1 \|}$

$ \newcommand{\inner}[2]{\langle #1, #2 \rangle}$

$ \newcommand{\Span}{\mathrm{span}}$

$ \newcommand{\id}{\mathrm{id}}$

$ \newcommand{\kernel}{\mathrm{null}\,}$

$ \newcommand{\range}{\mathrm{range}\,}$

$ \newcommand{\RealPart}{\mathrm{Re}}$

$ \newcommand{\ImaginaryPart}{\mathrm{Im}}$

$ \newcommand{\Argument}{\mathrm{Arg}}$

$ \newcommand{\norm}[1]{\| #1 \|}$

$ \newcommand{\Span}{\mathrm{span}}$ $ \newcommand{\AA}{\unicode[.8,0]{x212B}}$

$ \newcommand{\vectorA}[1]{\vec{#1}} % arrow$

$ \newcommand{\vectorAt}[1]{\vec{\text{#1}}} % arrow$

$ \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } $

$ \newcommand{\vectorC}[1]{\textbf{#1}} $

$ \newcommand{\vectorD}[1]{\overrightarrow{#1}} $

$ \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} $

$ \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} $

Learning Objectives

By the end of this section, you will be able to:

Differentiate between resistance and resistivity
Define the term conductivity
Describe the electrical component known as a resistor
State the relationship between resistance of a resistor and its length, cross-sectional area, and resistivity
State the relationship between resistivity and temperature

What drives current? We can think of various devices—such as batteries, generators, wall outlets, and so on—that are necessary to maintain a current. All such devices create a potential difference and are referred to as voltage sources. When a voltage source is connected to a conductor, it applies a potential difference V that creates an electrical field. The electrical field, in turn, exerts force on free charges, causing current. The amount of current depends not only on the magnitude of the voltage, but also on the characteristics of the material that the current is flowing through. The material can resist the flow of the charges, and the measure of how much a material resists the flow of charges is known as the resistivity . This resistivity is crudely analogous to the friction between two materials that resists motion.

Resistivity

When a voltage is applied to a conductor, an electrical field $\vec{E}$ is created, and charges in the conductor feel a force due to the electrical field. The current density $\vec{J}$ that results depends on the electrical field and the properties of the material. This dependence can be very complex. In some materials, including metals at a given temperature, the current density is approximately proportional to the electrical field. In these cases, the current density can be modeled as

\[\vec{J} = \sigma \vec{E},\]

where $\sigma$ is the electrical conductivity . The electrical conductivity is analogous to thermal conductivity and is a measure of a material’s ability to conduct or transmit electricity. Conductors have a higher electrical conductivity than insulators. Since the electrical conductivity is $\sigma = J/E$, the units are

\[\sigma = \dfrac{|J|}{|E|} = \dfrac{A/m^2}{V/m} = \dfrac{A}{V \cdot m}.\]

Here, we define a unit named the ohm with the Greek symbol uppercase omega, $\Omega$. The unit is named after Georg Simon Ohm, whom we will discuss later in this chapter. The $\Omega$ is used to avoid confusion with the number 0. One ohm equals one volt per amp: $1 \, \Omega = 1 \, V/A$. The units of electrical conductivity are therefore $(\Omega \cdot m)^{-1}$.

Conductivity is an intrinsic property of a material. Another intrinsic property of a material is the resistivity , or electrical resistivity . The resistivity of a material is a measure of how strongly a material opposes the flow of electrical current. The symbol for resistivity is the lowercase Greek letter rho, $\rho$, and resistivity is the reciprocal of electrical conductivity:

\[\rho = \dfrac{1}{\sigma}.\]

The unit of resistivity in SI units is the ohm-meter $(\Omega \cdot m$. We can define the resistivity in terms of the electrical field and the current density.

\[\rho = \dfrac{E}{J}.\]

The greater the resistivity, the larger the field needed to produce a given current density. The lower the resistivity, the larger the current density produced by a given electrical field. Good conductors have a high conductivity and low resistivity. Good insulators have a low conductivity and a high resistivity. Table $\PageIndex{1}$ lists resistivity and conductivity values for various materials.

Table $\PageIndex{1}$: Resistivities and Conductivities of Various Materials at 20 °C[1] Values depend strongly on amounts and types of impurities.
	$\sigma$ $(\Omega \cdot m)^{-1}$	$\rho$ $(\Omega \cdot m)$	$\alpha$ $(^oC)^{-1}$

Silver	$6.29 \times 10^7$	$1.59 \times 10^{-8}$	0.0038
Copper	$5.95 \times 10^7$	$1.68 \times 10^{-8}$	0.0039
Gold	$4.10 \times 10^7$	$2.44 \times 10^{-8}$	0.0034
Aluminum	$3.77 \times 10^7$	$2.65 \times 10^{-8}$	0.0039
Tungsten	$1.79 \times 10^7$	$5.60 \times 10^{-8}$	0.0045
Iron	$1.03 \times 10^7$	$9.71 \times 10^{-8}$	0.0065
Platinum	$0.94 \times 10^7$	$10.60 \times 10^{-8}$	0.0039
Steel	$0.50 \times 10^7$	$20.00 \times 10^{-8}$
Lead	$0.45 \times 10^7$	$22.00 \times 10^{-8}$
Manganin (Cu, Mn. Ni alloy)	$0.21 \times 10^7$	$48.20 \times 10^{-8}$	0.000002
Constantan (Cu, Ni alloy)	$0.20 \times 10^7$	$49.00 \times 10^{-8}$	0.00003
Mercury	$0.10 \times 10^7$	$98.00 \times 10^{-8}$	0.0009
Nichrome (Ni, Fe, Cr alloy)	$0.10 \times 10^7$	$100.00 \times 10^{-8}$	0.0004

Carbon (pure)	$2.86 \times 10^{4}$	$3.50 \times 10^{-5}$	-0.0005
Carbon	$(2.86 - 1.67) \times 10^{-6}$	$(3.5 - 60) \times 10^{-5}$	-0.0005
Germanium (pure)		$600 \times 10^{-3}$	-0.048
Germanium		$(1 - 600) \times 10^{-3}$	-0.050
Silicon (pure)		2300	-0.075
Silicon		0.1 - 2300	-0.07

Amber	$2.00 \times 10^{-15}$	$5 \times 10^{14}$
Glass	$10^{-9} - 19^{-14}$	$10^9 - 10^{14}$
Lucite	$< 10^{-13}$	$> 10^{13}$
Mica	$10^{-11} - 10^{-15}$	$10^{11} - 10^{15}$
Quartz (fused)	$1.33 \times 10^{-18}$	$75 \times 10^{16}$
Rubber (hard)	$10^{-13} - 10^{-16}$	$10^{13} - 10^{16}$
Sulfur	$10^{-15}$	$10^{15}$
Teflon	$< 10^{-13}$	$> 10^{13}$
Wood	$10^{-8} - 10^{-11}$	$10^8 - 10^{11}$

The materials listed in the table are separated into categories of conductors, semiconductors, and insulators, based on broad groupings of resistivity. Conductors have the smallest resistivity, and insulators have the largest; semiconductors have intermediate resistivity. Conductors have varying but large, free charge densities, whereas most charges in insulators are bound to atoms and are not free to move. Semiconductors are intermediate, having far fewer free charges than conductors, but having properties that make the number of free charges depend strongly on the type and amount of impurities in the semiconductor. These unique properties of semiconductors are put to use in modern electronics, as we will explore in later chapters.

Example $\PageIndex{1}$: Current Density, Resistance, and Electrical field for a Current-Carrying Wire

Calculate the current density, resistance, and electrical field of a 5-m length of copper wire with a diameter of 2.053 mm (12-gauge) carrying a current of $I - 10 \, mA$.

We can calculate the current density by first finding the cross-sectional area of the wire, which is $A = 3.31 \, mm^2$, and the definition of current density $J = \dfrac{I}{A}$. The resistance can be found using the length of the wire $L = 5.00 \, m$, the area, and the resistivity of copper $\rho = 1.68 \times 10^{-8} \Omega \cdot m$, where $R = \rho \dfrac{L}{A}$. The resistivity and current density can be used to find the electrical field.

First, we calculate the current density:

\[\begin {align*} J &= \dfrac{I}{A} \\[5pt] &= \dfrac{10 \times 10^{-3} A}{3.31 \times 10^{-6} m^2} \\[5pt] &= 3.02 \times 10^3 \dfrac{A}{m^2}. \end{align*}\]

The resistance of the wire is

\[\begin {align*}R &= \rho \dfrac{L}{A} \\[5pt] &= (1.68 \times 10^{-8} \Omega \cdot m) \dfrac{5.00 \, m}{3.31 \times 10^{-6}m^2} \\[5pt] &= 0.025 \, \Omega.\end{align*}\]

Finally, we can find the electrical field:

\[\begin {align*}E &= \rho J \\[5pt] &= 1.68 \times 10^{-8} \Omega \cdot m \left(3.02 \times 10^3 \dfrac{A}{m^2}\right) \\[5pt] &= 5.07 \times 10^{-5} \dfrac{V}{m}.\end{align*}\]

Significance

From these results, it is not surprising that copper is used for wires for carrying current because the resistance is quite small. Note that the current density and electrical field are independent of the length of the wire, but the voltage depends on the length.

Exercise $\PageIndex{1}$

Copper wires use routinely used for extension cords and house wiring for several reasons. Copper has the highest electrical conductivity rating, and therefore the lowest resistivity rating, of all nonprecious metals. Also important is the tensile strength, where the tensile strength is a measure of the force required to pull an object to the point where it breaks. The tensile strength of a material is the maximum amount of tensile stress it can take before breaking. Copper has a high tensile strength, $2 \times 10^8 \, \dfrac{N}{m^2}$. A third important characteristic is ductility. Ductility is a measure of a material’s ability to be drawn into wires and a measure of the flexibility of the material, and copper has a high ductility. Summarizing, for a conductor to be a suitable candidate for making wire, there are at least three important characteristics: low resistivity, high tensile strength, and high ductility. What other materials are used for wiring and what are the advantages and disadvantages?

Silver, gold, and aluminum are all used for making wires. All four materials have a high conductivity, silver having the highest. All four can easily be drawn into wires and have a high tensile strength, though not as high as copper. The obvious disadvantage of gold and silver is the cost, but silver and gold wires are used for special applications, such as speaker wires. Gold does not oxidize, making better connections between components. Aluminum wires do have their drawbacks. Aluminum has a higher resistivity than copper, so a larger diameter is needed to match the resistance per length of copper wires, but aluminum is cheaper than copper, so this is not a major drawback. Aluminum wires do not have as high of a ductility and tensile strength as copper, but the ductility and tensile strength is within acceptable levels. There are a few concerns that must be addressed in using aluminum and care must be used when making connections. Aluminum has a higher rate of thermal expansion than copper, which can lead to loose connections and a possible fire hazard. The oxidation of aluminum does not conduct and can cause problems. Special techniques must be used when using aluminum wires and components, such as electrical outlets, must be designed to accept aluminum wires.

View this interactive simulation to see what the effects of the cross-sectional area, the length, and the resistivity of a wire are on the resistance of a conductor. Adjust the variables using slide bars and see if the resistance becomes smaller or larger.

Temperature Dependence of Resistivity

Looking back at Table $\PageIndex{1}$, you will see a column labeled “Temperature Coefficient.” The resistivity of some materials has a strong temperature dependence. In some materials, such as copper, the resistivity increases with increasing temperature. In fact, in most conducting metals, the resistivity increases with increasing temperature. The increasing temperature causes increased vibrations of the atoms in the lattice structure of the metals, which impede the motion of the electrons. In other materials, such as carbon, the resistivity decreases with increasing temperature. In many materials, the dependence is approximately linear and can be modeled using a linear equation:

\[\rho \approx \rho_0 [1 + \alpha (T - T_0)],\]

where $\rho$ is the resistivity of the material at temperature T , $\alpha$ is the temperature coefficient of the material, and $\rho_0$ is the resistivity at $T_0$, usually taken as $T_0 = 20.00^oC$.

Note also that the temperature coefficient $\alpha$ is negative for the semiconductors listed in Table $\PageIndex{1}$, meaning that their resistivity decreases with increasing temperature. They become better conductors at higher temperature, because increased thermal agitation increases the number of free charges available to carry current. This property of decreasing $\rho$ with temperature is also related to the type and amount of impurities present in the semiconductors.

We now consider the resistance of a wire or component. The resistance is a measure of how difficult it is to pass current through a wire or component. Resistance depends on the resistivity. The resistivity is a characteristic of the material used to fabricate a wire or other electrical component, whereas the resistance is a characteristic of the wire or component.

To calculate the resistance, consider a section of conducting wire with cross-sectional area A , length L , and resistivity $\rho$. A battery is connected across the conductor, providing a potential difference $\Delta V$ across it (Figure $\PageIndex{1}$). The potential difference produces an electrical field that is proportional to the current density, according to $\vec{E} = \rho \vec{J}$.

Picture is a schematic drawing of a battery connected to a conductor with the cross-sectional area A. Current flows from high potential side to the low potential side of the conductor.

The magnitude of the electrical field across the segment of the conductor is equal to the voltage divided by the length, $E = V/L$, and the magnitude of the current density is equal to the current divided by the cross-sectional area, $J = I/A$. Using this information and recalling that the electrical field is proportional to the resistivity and the current density, we can see that the voltage is proportional to the current:

\[\begin{align*} E &= \rho J \\[4pt] \dfrac{V}{L} &= \rho \dfrac{I}{A} \\[4pt] V &= \left(\rho \dfrac{L}{A}\right) I. \end{align*}\]

Definition: Resistance

The ratio of the voltage to the current is defined as the resistance $R$:

\[R \equiv \dfrac{V}{I}.\]

The resistance of a cylindrical segment of a conductor is equal to the resistivity of the material times the length divided by the area:

\[R \equiv \dfrac{V}{I} = \rho \dfrac{L}{A}.\]

The unit of resistance is the ohm, $\Omega$. For a given voltage, the higher the resistance, the lower the current.

A common component in electronic circuits is the resistor. The resistor can be used to reduce current flow or provide a voltage drop. Figure $\PageIndex{2}$ shows the symbols used for a resistor in schematic diagrams of a circuit. Two commonly used standards for circuit diagrams are provided by the American National Standard Institute (ANSI, pronounced “AN-see”) and the International Electrotechnical Commission (IEC). Both systems are commonly used. We use the ANSI standard in this text for its visual recognition, but we note that for larger, more complex circuits, the IEC standard may have a cleaner presentation, making it easier to read.

Figure A shows the ANSI symbol for a resistor. Figure B shows the IEC symbol for a resistor.

Material and shape dependence of resistance

A resistor can be modeled as a cylinder with a cross-sectional area A and a length L , made of a material with a resistivity $\rho$ (Figure $\PageIndex{3}$). The resistance of the resistor is $R = \rho \dfrac{L}{A}$

Picture is a schematic drawing of a resistor. It is a uniform cylinder of length L and cross-sectional area A.

The most common material used to make a resistor is carbon. A carbon track is wrapped around a ceramic core, and two copper leads are attached. A second type of resistor is the metal film resistor, which also has a ceramic core. The track is made from a metal oxide material, which has semiconductive properties similar to carbon. Again, copper leads are inserted into the ends of the resistor. The resistor is then painted and marked for identification. A resistor has four colored bands, as shown in Figure $\PageIndex{4}$.

Picture is a schematic drawing of a resistor. It contains four colored bands: red, black, green, and grey.

Resistances range over many orders of magnitude. Some ceramic insulators, such as those used to support power lines, have resistances of $10^{12} \, \Omega$ or more. A dry person may have a hand-to-foot resistance of $10^5 \, \Omega$ whereas the resistance of the human heart is about $10^3 \, \Omega$ A meter-long piece of large-diameter copper wire may have a resistance of $10^{-5} \, \Omega$, and superconductors have no resistance at all at low temperatures. As we have seen, resistance is related to the shape of an object and the material of which it is composed.

The resistance of an object also depends on temperature, since $R_0$ is directly proportional to $\rho$. For a cylinder, we know $R = \rho \dfrac{L}{A}$, so if L and A do not change greatly with temperature, R has the same temperature dependence as $\rho$. (Examination of the coefficients of linear expansion shows them to be about two orders of magnitude less than typical temperature coefficients of resistivity, so the effect of temperature on L and A is about two orders of magnitude less than on $\rho$.) Thus,

\[R = R_0(1 + \alpha \Delta T) \label{Tdep}\]

is the temperature dependence of the resistance of an object, where $R_0$ is the original resistance (usually taken to be $T = 20.00^oC$ and R is the resistance after a temperature change $\Delta T$. The color code gives the resistance of the resistor at a temperature of $T = 20.00^oC$.

Numerous thermometers are based on the effect of temperature on resistance (Figure $\PageIndex{5}$). One of the most common thermometers is based on the thermistor, a semiconductor crystal with a strong temperature dependence, the resistance of which is measured to obtain its temperature. The device is small, so that it quickly comes into thermal equilibrium with the part of a person it touches.

Picture is a photograph of two digital oral thermometers.

Example $\PageIndex{2}$: Calculating Resistance

Although caution must be used in applying $\rho = \rho_0 (1 + \alpha \Delta T)$ and $R = R_0(1 + \alpha \Delta T)$ for temperature changes greater than $100^oC$, for tungsten, the equations work reasonably well for very large temperature changes. A tungsten filament at $20^oC$ has a resistance of $0.350 \, \Omega$. What would the resistance be if the temperature is increased to $2850^oC$?

This is a straightforward application of Equation \ref{Tdep}, since the original resistance of the filament is given as $R_0 = 0.350 \, \Omega$ and the temperature change is $\Delta T = 2830^oC$.

The resistance of the hotter filament $R$ is obtained by entering known values into the above equation:

\[\begin{align*} R &= R_0(1 + \alpha \Delta T) \\[5pt] &= (0.350 \, \Omega)\left(1 + \left(\dfrac{4.5 \times 10^{-3}}{^oC}\right)(2830^oC)\right) \\[5pt] &= 4.8 \, \Omega \end{align*} \]

Notice that the resistance changes by more than a factor of 10 as the filament warms to the high temperature and the current through the filament depends on the resistance of the filament and the voltage applied. If the filament is used in an incandescent light bulb, the initial current through the filament when the bulb is first energized will be higher than the current after the filament reaches the operating temperature.

Exercise $\PageIndex{2}$

A strain gauge is an electrical device to measure strain, as shown below. It consists of a flexible, insulating backing that supports a conduction foil pattern. The resistance of the foil changes as the backing is stretched. How does the strain gauge resistance change? Is the strain gauge affected by temperature changes?

Picture is a schematic drawing of a strain gauge device that consists of the conducting pattern deposited on the insulated surface. Metal contacts are made to the two large pads at the origin of the conducting pattern

The foil pattern stretches as the backing stretches, and the foil tracks become longer and thinner. Since the resistance is calculated as $R = \rho \dfrac{L}{A}$, the resistance increases as the foil tracks are stretched. When the temperature changes, so does the resistivity of the foil tracks, changing the resistance. One way to combat this is to use two strain gauges, one used as a reference and the other used to measure the strain. The two strain gauges are kept at a constant temperature

The Resistance of Coaxial Cable

Long cables can sometimes act like antennas, picking up electronic noise, which are signals from other equipment and appliances. Coaxial cables are used for many applications that require this noise to be eliminated. For example, they can be found in the home in cable TV connections or other audiovisual connections. Coaxial cables consist of an inner conductor of radius $r_i$ surrounded by a second, outer concentric conductor with radius $r_0$ (Figure $\PageIndex{6}$). The space between the two is normally filled with an insulator such as polyethylene plastic. A small amount of radial leakage current occurs between the two conductors. Determine the resistance of a coaxial cable of length L .

Picture is a schematic drawing of a coaxial cable. It consists of a central metal core encapsulated by the dielectric insulator. Metal shield surrounds dielectric insulator. The whole assembly in inserted in the plastic jacket.

We cannot use the equation $R = \rho \dfrac{L}{A}$ directly. Instead, we look at concentric cylindrical shells, with thickness dr , and integrate.

We first find an expression for $dR$ and then integrate from $r_i$ to $r_0$,

\[\begin{align*} dR &= \dfrac{\rho}{A} dr \\[5pt] &= \dfrac{\rho}{2 \pi r L} dr, \end{align*}\]

Integrating both sides

\[\begin{align*} R &= \int_{r_i}^{r_0} dR \\[5pt] &= \int_{r_i}^{r_0} \dfrac{\rho}{2 \pi r L} dr \\[5pt] &= \dfrac{\rho}{2\pi L} \int_{r_i}^{r_0} \dfrac{1}{r} dr \\[5pt] &= \dfrac{\rho}{2\pi L} \ln \dfrac{r_0}{r_i}.\end{align*}\]

The resistance of a coaxial cable depends on its length, the inner and outer radii, and the resistivity of the material separating the two conductors. Since this resistance is not infinite, a small leakage current occurs between the two conductors. This leakage current leads to the attenuation (or weakening) of the signal being sent through the cable.

Exercise $\PageIndex{3}$

The resistance between the two conductors of a coaxial cable depends on the resistivity of the material separating the two conductors, the length of the cable and the inner and outer radius of the two conductor. If you are designing a coaxial cable, how does the resistance between the two conductors depend on these variables?

The longer the length, the smaller the resistance. The greater the resistivity, the higher the resistance. The larger the difference between the outer radius and the inner radius, that is, the greater the ratio between the two, the greater the resistance. If you are attempting to maximize the resistance, the choice of the values for these variables will depend on the application. For example, if the cable must be flexible, the choice of materials may be limited.

Phet: Battery-Resistor Circuit

View this simulation to see how the voltage applied and the resistance of the material the current flows through affects the current through the material. You can visualize the collisions of the electrons and the atoms of the material effect the temperature of the material.

Sign in / Register
Administration
Edit profile

The PhET website does not support your browser. We recommend using the latest version of Chrome, Firefox, Safari, or Edge.

Misconceptions
Classroom Physics

Share this article:

Electrical resistance, episode 107: preparation for resistance topic, episode 108: resistance, episode 109: electrical characteristics, episode 110: resistance and temperature, episode 111: semiconductor devices, episode 112: resistivity.

Lesson for 16-19

The central idea is that of electrical resistance - what it is, how it can be measured, how it arises and what affects it. We begin by relating resistance to current and voltage through the electrical characteristics of various components (at the same time providing more practice in setting up electrical circuits and using ammeters and voltmeters). This will naturally introduce some of the key factors affecting resistance - choice of material, temperature, light intensity...

Next we investigate the temperature dependence of the resistance of metals and semiconductors and (where relevant) discuss the phenomenon of superconductivity and its applications. An investigation of the dependence of resistance on type of material and dimensions leads to resistivity. The electrical behaviour of different types of material can then be linked back to their microscopic structure.

Preparation for resistance topic

Teaching Guidance for 16-19

Level Advanced

Most multimeters can function as ohm meters, for measuring resistance directly. They apply a small voltage to the component being tested and then measure the current it draws. Ohm meters must only be connected directly across the components they are measuring, which must be removed from any other circuits.

You will have to teach your students how to use micrometer screw gauges to measure diameters of thin wires. This can also form the basis of a useful lesson in handling errors in measurements.

Check with your technician or other support staff that you have enough suitable diodes and thermistors, and check also the supplies of bare constantan and nichrome wire. You may also wish to check the availability of conducting paper or conducting putty for the experiments on resistivity, but you can use more conventional wire if they are not available.

Find a table of values of the electrical resistivity of materials (conductors and insulators). This property covers a greater range of values than any other material property.

Main aims of this topic

Electrical Resistance

Students will:

measure the I - V characteristics of metals, carbon resistors, semiconductor diodes and filament lamps
define resistance
use an ohm meter
state and use Ohm’s law
describe and explain the effect of temperature on the resistance of a metal and of a thermistor
describe and explain the effect of light on an LDR
investigate the dependence of resistance on length and cross-sectional area using resistive putty and resistive paper
make measurements of resistivity
perform calculations involving resistivity

Prior knowledge

Students should have previously encountered the equation R = V I , which defines resistance. They should also be familiar with the idea that metals contain free electrons, which is why they conduct well (both electricity and energy).

Where this leads

Students will have extended their understanding of the microscopic nature of electrical current in solid materials. This will help later in understanding the internal resistance of cells and power supplies, as well as other currents such as electron beams.

Activity time 85 minutes

The idea of resistance should be familiar (although perhaps not secure) from pre-16 science course, so there is no point pretending that this is an entirely new concept. A better approach is to draw out what they know. The aim of this first episode is to provide a quantitative definition for resistance ( R = V I ) which reinforces the qualitative notion that more resistance means less current. In addition, we will look at Ohm’s law, which is not the same thing as the definition of resistance.

Lesson Summary

Demonstration: The meaning of resistance (10 minutes)
Discussion: Defining resistance (10 minutes)
Worked Example: Calculating resistance (5 minutes)
Student Questions: Simple calculations (10 minutes)
Student Experiment: Characteristics of metal wire (40 minutes)
Discussion: Ohm’s law. (10 minutes)

Demonstration: The meaning of resistance

Illustrate the idea of resistance with a quick demonstration. It should be clear from the demonstration that, as more resistors are added (in series) the current (and brightness of the lamp) fall whilst the voltage (electrical push) remains constant. Lead them to the idea that resistance determines the number of volts per amp needed to maintain the current.

Episode 108-1: Increasing resistance decreases current (Word, 27 KB)

Discussion: Defining resistance

Now define resistance: R = V I pointing out that this is the ratio of the pd across a component to the current flowing through it (i.e. literally volts per amp ). Define the ohm ( Ω ) (again point out that 1 ohm is 1 volt per amp ).

1 Ω = 1 V A -1

Point out that kilo-ohms (k Ω ) and mega-ohms (M Ω ) are commonly used:

1 k Ω is 1000 Ω ; 1 M Ω is 1000 k Ω , so 1 000 000 Ω .

Worked examples: Calculating resistance

Calculate the resistance of a lamp when a pd of 10 V makes a current of 2 mA flow through it. (This will give practice in handling powers of 10.)

R = 10 V 2 × 10 -3 A

R = 5000 Ω , or R = 5 k Ω .

Student questions: Simple calculations

With weak groups it may be worth spending a few minutes letting them calculate resistances from R = V I when currents are given in amps, milli-amps and micro-amps. This will save errors later when they measure their own currents and use the results to calculate resistance.

Episode 108-2: Introductory questions on resistance (Word, 22 KB)

Student experiment: Characteristics of metal wire

This episode concludes by measuring the voltage/current characteristic for a metal (constantan) wire. (This could be included with the other characteristics in the next episode but if it is done prior to those then Ohm’s Law can be used to interpret later results – leading to the ideas of ohmic and non-ohmic behaviour).

Episode 108-3: Electrical characteristics of a metal wire (Word, 63 KB)

Discussion: Ohm’s law

Most electrical engineers identify the equation V = I × R with Ohm’s Law but this won’t do for post-16 examinations! Historically, Ohm showed that the resistance of a metal under constant physical conditions (particularly temperature) is constant. The experiment above should have demonstrated this by generating a straight line graph that passes through the origin: if I is directly proportional to V (or the other way around) then Ohm’s law is obeyed. Any conductor (metallic or otherwise) that behaves in this way is described as an ohmic conductor .

It might well be worth spending some time reinforcing the meaning of directly proportional and emphasising that the graphical characteristic is a straight line graph that passes through the origin.

Episode 108-4: Electrical characteristics of a resistor (Word, 25 KB)

Download this episode

Electrical characteristics.

Activity time 120 minutes

In this episode, students measure the current and voltage characteristics for several components, and identify ohmic and non-ohmic behaviour.

Student experiment: Further characteristics (40 minutes)
Student experiment – alternative version: Further characteristics (40 minutes)
Discussion: The results (10 minutes)
Student questions: On characteristics (30 minutes)

Student experiment: Further characteristics

Students determine the V - I characteristics for a carbon resistor, semiconductor diode and filament lamp.

This activity is best carried out individually (if space and apparatus allows this) so that each student has to construct and test his/her own circuit. One of the dangers of always working in pairs is that some students who lack confidence in circuit building will always avoid having to do it. This activity gives good practice in building testing and using a circuit designed to measure current and voltage.

They will need a reasonable amount of time to set up, check the circuit and begin to take readings. Make sure they all have correct circuits and that their meters are set to appropriate ranges (many take a long time to come to terms with multimeters). I would suggest about 40 min on the practical work itself. This should allow them all to collect data for all three components.

Some will work much faster than this so it may be worth having some additional activities available (e.g. the characteristic for thermistor).

Data collection can be handled in two ways: Simply record the data into a prepared table, or record directly into Excel or a similar spreadsheet package.

Episode 109-1: Electrical characteristics (Word, 59 KB)

Student experiment – alternative version

If you have access to datalogging equipment, this is a good opportunity to get students to set up and record results automatically.

If a pc projector is available it is worth collecting one set of data to use at the end of the practical session (you could generate this yourself or else harvest a reliable set from one of the students/groups).

Episode 109-2: Electrical characteristics – datalogging alternative (Word, 31 KB)

Discussion: The results

In either case it is useful to bring the class together at the end of the practical session (say, 15 minutes before the end of the lesson) to discuss results. If you have collected some sample data you can show them how to process this in real time using Excel and a PC projector. Use this to instruct them about trend lines (don’t join the dots and don’t let Excel take over!). For some or all it may be worthwhile to recommend plotting by hand.

This may be the first time they have plotted graphs in Physics that include points in more than one quadrant, so this can be illustrated and discussed. Use terms such as ohmic and non-ohmic and encourage them to do the same. Reinforce the idea that an ohmic conductor is distinguished by a straight-line graph that passes through the origin. Remind them that resistance is the ratio of V to I not the gradient of the graph (particularly important when discussing the filament lamp).

Student questions: On characteristics

Students will get confused between V against I and I against V graphs. Both will be encountered so they should be prepared.

Episode 109-3: Lamp and resistor in series (Word, 41 KB)

Episode 109-4: Using non-ohmic behaviour (Word, 109 KB)

Resistance and temperature

Activity time 115 minutes

This episode looks at the resistance of a metal and a semiconductor, giving a microscopic explanation of the variation with temperature. There is also a brief look at superconductivity and its applications.

Demonstration and discussion: Resistance and temperature (10 minutes)
Discussion: Free-electrons in metals (10 minutes)
Student experiment: Thermistor behaviour (20 minutes)
Discussion and demonstration: Conduction in semiconductors (5 minutes)
Discussion: Superconductivity (20 minutes)
Student activity: Researching superconductivity (30 minutes plus time for reporting back)
Student questions: Using these ideas (20 minutes)

Discussion and demonstrations: Resistance and temperature

This episode picks up on the variation of resistance of the filament lamp. Students’ own results should show that the resistance increases with current. Link this to the change of temperature of the wire and remind them that metals obey Ohm’s Law if the temperature is constant. (When they measured the resistance of the constantan wire in Episode 109, the current was always small, so temperature was almost constant.) You can reinforce the idea of resistance change in metals by cooling a wire and showing that its resistance decreases. This can be done using a cooling spray or, more dramatically, using liquid nitrogen (if this is available).

Episode 110-1: Metal resistance decreases as temperature falls (Word, 43 KB)

Discussion: Free-electrons in metals

It is worth pausing at this point to discuss the mechanism of metallic resistance. Remind students of the model whereby as temperature increases the thermal vibrations in the lattice increase causing more electron scattering. (Be aware that there is more here than meets the eye in terms of quantum, as opposed to classical, free electron theory). This increases the resistance of the metal.

Next consider semiconductors. Students are unlikely to know much about semiconductors so it may be worth giving a brief introduction by saying that, compared to metals, they have only a few free electrons, so resistance (resistivity is the more appropriate term here, but they have not yet met it) is much higher. However, semiconductors such as silicon are central to the electronics industry so it is well worth considering their electrical characteristics. For example, how does their resistance depend on temperature?

Student experiment: Thermistor behaviour

Students can investigate the temperature dependence of the resistance of a thermistor for themselves.

The results should show a clear decrease of resistance with increasing temperature. This is the opposite of what happened with the metal.

NB These thermistors are n.t.c. types (negative temperature coefficient). Other types exist which have a non-linear positive temperature coefficient.

Episode 110-2: Calibration of a thermistor (Word, 39 KB)

Discussion and demonstrations: Conduction in semiconductors

Ask whether the atoms in the semiconductor vibrate more at higher temperature. Of course they do – so this contribution to resistance must increase in the same way as for a metal. So what else could make the semiconductor conduct better? The answer is: more charge carriers. Whereas the number of free electrons in a metal is constant the effect of heating a semiconductor frees additional electrons (and holes, but it’s probably not worth mentioning them yet!). For silicon in this temperature range the effect of additional charge carriers outweighs the effect of additional vibrations.

An interesting additional demonstration can be done using a different semiconductor (carbon). This shows that the two effects compete with each other. At lower temperatures the increase in resistance due to vibration dominates, as temperature rises, more and more electrons are freed and the resistance begins to fall.

Discussion: Superconductivity

Having introduced the idea that metallic resistance is caused by electron scattering from ions as they vibrate you should return to what happens as a metal is cooled down.

You are looking for an argument that runs along the lines of: lower temperature, smaller amplitude of vibration so reduced scattering and therefore reduced resistance. Refer back to the initial demonstration.

How low can we go?

The students ought to predict that thermal vibrations will eventually stop (at absolute zero on a simple mechanical model). This implies a very low resistance at low temperatures (but not necessarily zero).

Lead into Kammerlingh Onnes’s work and his surprise that mercury’s resistance disappears at a very low temperature (a few degrees above absolute zero: 4.15 K).

This sudden transition was unexpected and is a quantum effect. It occurs for some but not all metals. It has also been observed at much higher temperatures (around 150 K) in certain ceramics. These are called high temperature superconductors (even though we are still talking about temperatures more than 100 degrees below zero Celsius! The mechanism for high temperature superconductivity is not fully understood and it is hoped that in future we may be able to manufacture room temperature superconductors.

Rather than lecture them about superconductors this would be a good opportunity to set them some research tasks which can be reported back to the class. Here is a work sheet that could be used:

Episode 110-3: Researching superconductivity (Word, 27 KB)

Student questions: Using these ideas

Episode 110-4: Filament lamp and thermistor in series (Word, 31 KB)

Semiconductor devices

Activity time 50 minutes

Light dependent resistors (LDRs) are probably already familiar. Like thermistors, they are semiconductor devices. Their behaviour can be illustrated by experiment and explained in a similar way to the variation of resistance with temperature for a semiconductor thermistor.

Student experiment: Characteristics of an LDR (30 minutes)
Demonstration: Semiconductor devices in use (20 minutes)

If your specification requires it, this is a good time to look at semiconductor devices in general.

Student experiment: Characteristics of an LDR

Students look at the changing resistance of an LDR as the light intensity is varied.

Explain that photons of light absorbed by the LDR free electrons to conduct, reducing the resistance.

Episode 111-1: Variation of resistance of an LDR with light intensity (Word, 25 KB)

Demonstration: Semiconductor devices in use

If you have plenty of time you could ask the students to construct some of these circuits. Otherwise set them up as a circus of demonstrations and use each one to demonstrate how the components can be used.

Don’t forget to mention the key role of silicon in the electronic and computing industries!

Episode 111-2: Applications of semiconductor devices (Word, 26 KB)

Resistivity

Activity time 110 minutes

In this episode, students learn how and why the resistance of a wire depends on the wire’s dimensions. They learn the definition of resistivity and use it in calculations.

Discussion: Variation of resistance with length and area (5 minutes)
Student experiment: Variation of resistance with length and area (30 minutes)
Discussion: Variation of resistance with length and area (10 minutes)
Student experiment: Measurement of resistivity (30 minutes)
Student questions: Using these ideas (30 minutes)

Discussion: Variation of resistance with length and area

The analogy to water flow will be useful here – ask them how they think the flow rate will be affected if you increase the cross-sectional area or length of the pipe along which the water has to flow. This should lead to two predictions about the resistance of a wire:

resistance increases with length
resistance decreases with diameter or cross-sectional area

It will be worth reminding them that doubling the diameter quadruples the cross-sectional area; many students get confused about the distinction and expect a wire of double diameter to have half the resistance.

Student experiment: Variation of resistance with length and area

You could ask them to do one or both of the following experiments. Both reinforce the idea that resistance depends on material dimensions:

Episode 112-1: How the dimensions of a conductor affect its resistance (Word, 44 KB)

Episode 112-2: Introduction to resistivity using conducting paper (Word, 49 KB)

Follow up with some theory suggesting:

Resistance is proportional to length l

Resistance is inversely proportional to cross-sectional area A

resistance = constant × length cross-section area

The constant is a property of the material used – its resistivity ρ.

R = ρ × l A

The units of resistivity can be derived from the equation: Ω m .

Emphasise that this is ohm metre , not ohm per metre .

Discuss the great range of resistivities amongst materials. Values for metals are very small. The resistivity of a material is numerically equal to the resistance between opposite faces of a one-metre-cube of the material; although this is not a good definition of resistivity, imagining such a block of metal does indicate why its value should be so low ( ~ 10 -9 Ω m ).

Student experiment: Measurement of resistivity

Complete this section by asking your students to measure the resistivity of several metal wires.

This experiment provides an opportunity for a detailed discussion of the treatment of experimental errors.

Episode 112-3: Measuring electrical resistivity (Word, 30 KB)

Problems involving resistivity.

Students often get confused between cross-section area and diameter.

Make sure they are able to convert mm 2 to m 2 for resistivity calculations.

Episode 112-4: Electrical properties (Word, 28 KB)

Support our manifesto for change

The IOP wants to support young people to fulfil their potential by doing physics. Please sign the manifesto today so that we can show our politicians there is widespread support for improving equity and inclusion across the education sector.

Physics Links Explorer

s Science Experiments

]
]
]
]
]
]
]
]

is a measure of how strongly a standard volume of material opposes the flow of electric current.

is a measure of how strongly a bulk of material opposes the flow of electric current.

Temperature dependence

In general, electrical resistivity of metals increases with temperature, while the resistivity of semiconductors decreases with increasing temperature. In both cases, electron-phonon interactions can play a key role. At high temperatures, the resistance of a metal increases linearly with temperature. As the temperature of a metal is reduced, the temperature dependence of resistivity follows a power law function of temperature. Mathematically the temperature dependence of the resistivity ρ of a metal is given by the Bloch-Gruneissen formula :

$\rho(T)=\rho(0)+A\left(\frac{T}{\Theta_R}\right)^n\int_0^{\frac{\Theta_R}{T}}\frac{x^n}{(e^x-1)(1-e^{-x})}dx$

where ρ(0) is the residual resistivity due to defect scattering, A is a constant that depends on the velocity of electrons at the fermi surface, the Debye radius and the number density of electrons in the metal. Θ R is the Debye temperature as obtained from resistivity measurements and matches very closely with the values of Debye temperature obtained from specific heat measurements. n is an integer that depends upon the nature of interaction:

n=5 implies that the resistance is due to scattering of electrons by phonons (as it is for simple metals)
n=3 implies that the resistance is due to s-d electron scattering (as is the case for transition metals)
n=2 implies that the resistance is due to electron-electron interaction.

As the temperature of the metal is sufficiently reduced (so as to 'freeze' all the phonons), the resistivity usually reaches a constant value, known as the residual resistivity . This value depends not only on the type of metal, but on its purity and thermal history. The value of the residual resistivity of a metal is decided by its impurity concentration. Some materials lose all electrical resistivity at sufficiently low temperatures, due to an effect known as superconductivity.

An even better approximation of the temperature dependence of the resistivity of a semiconductor is given by the Steinhart-Hart equation:

$1/T = A + B \ln(\rho) + C (\ln(\rho))^3 \,$

where A , B and C are the so-called Steinhart-Hart coefficients .

This equation is used to calibrate thermistors.

Complex resistivity

When analysing the response of materials to alternating electric fields, as is done in certain types of tomography, it is necessary to replace resistivity with a complex quantity called impeditivity , in analogy to electrical impedance. Impeditivity is the sum of a real component, the resistivity, and an imaginary component, the reactivity (reactance) .

Resistivity density products

In some applications where the weight of an item is very important resistivity density products are more important than absolute low resistivity- it is often possible to make the conductor thicker to make up for a higher resistivity; and then a low resistivity density product material (or equivalently a high conductance to density ratio) is desirable. For example, for long distance overhead power lines— aluminium is frequently used rather than copper because it is lighter for the same conductance.

In practice, calcium and the alkali metals are rarely used for conductors due to their high reactivity with water and oxygen.

Source: Wikipedia (All text is available under the terms of the GNU Free Documentation License and Creative Commons Attribution-ShareAlike License .)

Core Practical 7: Investigating Resistivity ( Edexcel International A Level Physics )

Revision note.

Core Practical 7: Investigating Resistivity

Aims of the experiment.

The aim of the experiment is to determine the resistivity of a length of wire
Independent variable = Length, L , of the wire (m)
Dependent variable = The current, I , through the wire (A)
Voltage across the wire
The material the wire is made from

Equipment List

Metre ruler = 1 mm
Micrometer screw gauge = 0.01 mm
Voltmeter = 0.1 V
Ammeter = 0.01 A

Apparatus diagram, downloadable AS & A Level Physics revision notes

The measurement should be taken between 5-10 times randomly along the wire.
Calculate the mean diameter from these values
The ammeter is connected in series and the voltmeter in parallel with the wire
Check that this is the voltage across the wire on the voltmeter
This is to prevent the wire from heating up and changing the resistivity
In this example, a 2.0 m wire is used.
The original length and the intervals can be changed (e.g. start at 0.1 m and increase in 0.1 m intervals), as long as there are 8-10 readings
Record the current for each length at least 3 times and calculate an average current, I
For each length, calculate the average resistance of the length of the wire using the equation

R = average resistance of the length of the wire (Ω)
V = potential difference across the circuit (V)
I = the average current through the wire for the chosen length (A)
An example of a table of results might look like this:

Example table of Results, downloadable AS & A Level Physics revision notes

Analysis of Results

The resistivity, ρ , of the wire is equal to

ρ = resistivity (Ω m)
R = resistance (Ω)
A = cross-sectional area of the wire (m 2 )
L = length of wire (m)
Rearranging for the resistance, R, gives:

Gradient, m = ρ / A
Plot a graph of the length of the wire, L , against the average resistance of the wire
Draw a line of best fit
Calculate the gradient
Multiply the gradient by cross-sectional area, A

ρ = gradient × A

Example Graph sketch, downloadable AS & A Level Physics revision notes

Evaluating the Experiment

Systematic Errors:

Otherwise, this could cause a zero error in your measurements of the length

Random Errors:

The resistivity of a material depends on its temperature
The current flowing through the wire will cause its temperature to increase
Therefore the temperature is kept constant by small currents
So that there isn't a temperature rise
This will reduce random errors in the reading
Make at least 5-10 measurements of the diameter of the wire with the micrometer

Safety Considerations

Make sure never to touch the wire directly when the circuit is switched on
Switch off the power supply right away if you smell burning
This could damage the electrical equipment
Or cause a short circuit which will affect the results

Worked example

A student conducts an experiment to find the resistivity of a constantan wire.

They attach one end of the wire to a circuit that contains a 6.0 V battery. The other end of the wire is attached by a flying lead to the wire at different lengths.

Worked example table 1, downloadable AS & A Level Physics revision notes

Step 1: Complete the average current and resistance columns in the table

The resistance is calculated using the equation

Worked example solution table, downloadable AS & A Level Physics revision notes

Step 2: Calculate the cross-sectional area of the wire from the diameter

The average diameter is 0.191 mm = 0.191 × 10 –3 m
The cross-sectional area is equal to

Step 3: Plot a graph of the length L against the resistance R

Worked example gradient from graph 1, downloadable AS & A Level Physics revision notes

Step 4: Calculate the gradient of the graph

Worked example gradient from graph, downloadable AS & A Level Physics revision notes

Step 5: Calculate the resistivity of the wire

You've read 0 of your 0 free revision notes

Get unlimited access.

to absolutely everything:

Downloadable PDFs
Unlimited Revision Notes
Topic Questions
Past Papers
Model Answers
Videos (Maths and Science)

Join the 100,000 + Students that ❤️ Save My Exams

the (exam) results speak for themselves:

Did this page help you?

Author: Joanna

Joanna obtained her undergraduate degree in Natural Sciences from Cambridge University and completed her MSc in Education at Loughborough University. After a decade of teaching and leading the physics department in a high-performing academic school, Joanna now mentors new teachers and is currently studying part-time for her PhD at Leicester University. Her passions are helping students and learning about cool physics, so creating brilliant resources to help with exam preparation is her dream job!

Science & Math
Sociology & Philosophy
Law & Politics

Lab Report Explained: Length and Electrical Resistance of a Wire

Lab Report Explained: Length and…

INTRODUCTION AND BACKGROUND THEORY

When electrons travel through wires or other external circuits, they travel in a zigzag pattern that results in a collision between the electrons and the ions in the conductor, and this is known as resistance. The resistance of a wire causes difficulty for the flow of the electrical current of a wire to move and is typically measured in Ohms (Ω).

George Ohm discovered that the potential difference of a circuit corresponds to the current flowing throughout a circuit and that a circuit sometimes resists the flow of electricity. The said scientist hence came up with a rule for working out resistance, shown on the image on the side:

Resistance is an important factor to pay attention to because, one, an overly-high resistance can cause a wire to overheat due to the friction that is caused when the electrons move against the opposition of resistance, which is potentially dangerous as it could melt or even set fire. It is therefore important to take note of the resistance when dealing with wires to supply power to a device or so.

A real life application would be a toaster where the wires are sized to get hot enough to toast bread but not enough to melt.

Secondly, resistance can also be used a very useful tool that enables you to control certain things. An example from the real-life world would be LED lights that require a resistor to control the flow of the electrical current to prevent getting damaged by high electrical current. Another example would be the volume control on a radio where a resistor is used to portion out the signal, which allows you to control the volume level.

It is clear now that resistance is an important attribute that has been applied to many forms of technology to perform a useful function, and this experiment aims to see how we can control it. The resistance of a wire varies according to the four factors of the wire; are temperature, material, diameter/thickness, and length of the wire.

This experiment will be focusing specifically on that last factor – length – and investigate just how much of a role a length of a wire would have on its electrical resistance by using a range of wire lengths to test with.

RESEARCH QUESTION

How does changing the length of a nichrome wire with a diameter of 0.315 mm – cut into measurements of 10cm, 20cm, 30cm, 40cm and 50cm — affect the electrical resistance generated within the nichrome wires that can be captured by an ohmmeter while keeping the temperature and the location of the experiment controlled?

If the length of nichrome wire is increased by an increment of 10cm starting from 10cm in length, then the graph measuring the electrical resistance of the wires will observe a positive slope with the mathematical function of y = mx that displays the increasing amount of resistance generated.

REASON FOR HYPOTHESIS

Doubling a length of a wire is just like having two of the shorter wires in series. If one short wire has a resistance of 1 ohm, then 2 shorts wires would have a resistance of 2 ohms when connected in series.

A longer wire also means that it would have more atoms, which means it will be more likely for moving electrons to collide with them; hence, higher resistance. For instance, a 10cm wire has 5 atoms, a 20cm wire has 10 atoms. If say 5 electrons try to pass through those two wires, the chances of them bumping into atoms are higher in the 20cm wire than the 10cm one. Therefore, the longer the wire, the higher the resistance.

Source: “Resistance” Physics Classroom. The Physics Classroom, n.d. Web. May 8. 2018. [http://www.physicsclassroom.com/class/circuits/Lesson-3/Resistance]





The experiment will work with 5 sets of nichrome	Each wire will be measured with an ohmmeter of
wires, starting from the length of 10 cm, added	a multimeter with an uncertainty of ±0.01Ω
with increments of 10cm. The lengths of each wire	accurately by clipping the probes of the ohmmeter
will be measured in cm with a 30 cm ruler with an	to the edges of the nichrome wires that are to be
uncertainty of ±0.05cm and will be as follows: 10,	tested.
20, 30, 40, 50.




	Different materials have different	The material of wire that will be
	resistances; some are better conductors,	used throughout the entire
	meaning they have more free electrons,	experiment will be kept exactly
	thus having less resistance.	the same, that is nichrome wire.
	Materials also have different heating
	point. Some heat up easier than others
	after use, which could potentially be
	dangerous.

	A diameter of a wire is one of the factors	The diameter of the wire that will
	that could affect a wire’s resistance for	be used throughout the entire
	there will be more room available for the	experiment will be kept exactly
	electrons to flow through, which would	the same, that is 0.315 mm.
	result in less resistance. Keeping the
	diameter of the wires constant would
	result in a fair experiment

	Working in different temperatures can	The temperature will be kept at
	affect the resistance of the wire because	room temperature, which can
	the higher the temperature, the higher	be done by simply doing the
	the resistance of the wire since it causes	experiment in one room, within
	the electrons will move faster due to an	the same period of time. The
	increase in energy, resulting in more	experimenters should also avoid
	collision with the atoms, thus more	using any light, such as a torch,
	resistance.	for it can be a source of heat.

	The power supply has to be kept the	The voltage will kept as 1.5 V,
	same as the voltage and current sent	and the current would change
	depends on it; the higher power supply	depending on the voltage.
	voltage, the more voltage and current will
	be sent to the wire, which would affect
	the resistance.

MATERIAL AND APPARATUS



Nichrome wire	150cm	1

Scissors	–	1

Digital multimeter	–	1	±0.01cm

Positive and negative multimeter probes	–	2

Ruler	30cm	1	±0.05cm

Sandpaper		1

EXPERIMENT DESIGN SETUP WITH CLEAR LABELS

Put on safety goggles, lab coats, gloves and masks for safety.
Handle all materials carefully.
Have a clear and clear working space for the experiment.
Do not consume any of the materials used, and keep them away from the eyes.
Complete all trials in the same area/room, at the same time of the day, using the same materials.
Clean up the lab area after the experiment.
Wash all materials thoroughly with warm water and soap after the experiment.

EXPERIMENT METHOD/PROCEDURE

Gather materials and set up the circuit as shown in the experiment diagram above.
Set the multimeter into ohmmeter, and connect the red probe to the output that says COM and the black probe to the output that has the mAVΩ label.
Get 150cm of nichrome wire and scrap or rub it with sandpaper in order to make it conductive.
Cut the wire with scissors into 5 separate wires with measurements of 10, 20, 30, 40 and 50cm.
Measure each wire by putting the points of both probes to the edges of the wires, and measure them four times/trials each.
Record the resistance reading from the multimeter of each of the 5 wires.

Recorded Resistance for 5 Different Lengths of Nichrome Wire





	unit: cm				unit: Ω
	inst. uncertainty:		instrument uncertainty: ±0.01


	±0.05cm
						(max-min)/2



1	10.00	3.50	3.50	3.50	3.40	3.48
	0.05

2	20.00	4.40	4.50	4.70	4.70	4.58	0.2


3	30.00	6.50	7.00	6.60	7.90	7.00	0.7


4	40.00	7.80	7.00	7.50	7.78	7.78
	0.9

5	50.00	8.40	7.00	8.60	8.48	8.48	0.6

SAMPLE CALCULATION OF PROCESSED DATA

Average data no. 3: (6.50+7.00+6.50+7.90) ÷ 4 = 6.98 Average uncertainty data of no. 3: (7.90-6.50) ÷ 2 = 0.70

GRAPH (based on average data)

CONCLUSION & EVALUATION

The graph shows an increasing linear trend-line with the mathematical function of Y = 0.132X + 2.3, which displays a positive correlation as seen in the line that goes above and to the right, which indicates positive values, as well as the gradient that displays a positive value. The graph also has an identified slope or gradient of 0.132.

This unit for this gradient is ohm/cm, and the gradient represents the rate of the overall increase in the dependent variable as the independent variable progresses. The slope reveals that when the length of a wire is increased, the resistance would go up by an approximate measurement of 1.25 Ω, which could be proven by the calculation of the graph where all the average was calculated from the average increments of each wire — (0.7+0.78+2.42+1.1)÷4=1.25.

Another aspect from the mathematical function that can be identified is the Y intercept which was 2.3, and it represents the average resistance (dv) of the first data of the independent variable, which was 3.48 Ω.

The data for the length of wires (independent variable) was 10cm to 50cm with an increment of 10cm between each wire, while the resistance (dependent variable) seemed to display the lowest data of 3.48 Ω and the highest data of 8.48 Ω, which seems to fit well with modeled best fit line graph, which is visibly supported by the coefficient determination (R2) which states that the best-fit line fits the scattered data by 94.98%

The data does not perfectly fit the modeled best fit line as errors did occur along with the experiment, as displayed by the rather large error bars over the data. The maximum error bar that can be identified there is the 4th independent variable, which was the 40cm wire, and the minimum error bar was located in the 1st data, which was the 10cm wire.

Two data of the largest errors went way above the predicted line, which from it we can infer that the collected data is considered to have an inconsistent precision. When coming to measure those two data, the data gained from each trial were very inconsistent, which was presumably caused by the inconsistent rubbing with sandpaper, which will be further elaborated in the suggestions for improvements.

The pattern on the graph supports the hypothesis of the experiment which predicted that if the length of the wire increased, the resistance measured would increase as well, the graph will observe a positive gradient with the mathematical function of y = mx + c which is supposed to display the increasing amount of resistance.

This was proven and supported by the trend-line in the graph which basically shows a positive correlation in the increase in resistance at the same rate as the independent variable increases, which is just as the hypothesis predicted. The graph also manifested a positive mathematical function of y = 0.132x + 2.3 with a positive gradient (0.132x) as well.

There is, however, a scientific explanation behind all this. It has been a known fact that the length of a wire is one of the four factors that have a role in the resistance of the wire, and this experiment has simply confirmed it.

The logical explanation would be that a longer wire also means that it would have more atoms, which means it will be more likely for moving electrons to collide with them; hence, higher resistance. For instance, a 10cm wire has 5 atoms, a 20cm wire has 10 atoms. If say 5 electrons try to pass through those two wires, the chances of them bumping into atoms are higher in the 20cm wire than the 10cm one. Therefore, the longer the wire, the higher the resistance.

In conclusion, the experiment was a successful investigation that successfully answers the research question of how basically changing the length of a wire (especially a nichrome wire with a diameter of 0.315 cut into measurements of 10cm, 20cm, 30cm, 40cm and 50cm) could affect the electrical resistance generated within the wires.

The investigation has concluded that there is a clear relationship between the length and the resistance of a wire and that the former does in fact affect the latter.

EVALUATION AND SUGGESTIONS



The inconsistent	The wires that were used for the	After looking at jewellery crafting
form of the wire	experiment were all cut from a long roll	tutorials, I have discovered a method
	of nichrome wire, and because they	of straightening wires, which was to
	have been rolled for a significant	hold them on the other edge while
	amount of time and due to their stiff	the other hand that is pulling the wire
	form, it was hardly possible to	out from the roll/coil straightens it
	completely straighten the wires. So	with heat and a strong pinch, which
	because the wires were still rather	would require gloves, and that was
	coiled up, the experimenters were not	something we did not do. Therefore,
	able to get the precise measurements	the next time we work with wires, it
	of the wires.	would be a good idea to ensure that
		they are straight when they are still
		fresh from the roll with the aid of
		tutorials from the internet to know
		how to straighten them properly




Inaccuracy of	The wires were measured and cut	It would have been much easier if
measurements of	manually, with a ruler and scissor, and	we straightened the wires
wire lengths	because it was done manually by	beforehand so we could simply tape
	humans, human errors were inevitable,	the wires unto the ruler, and carefully
	causing us to not being able to	observe the measurements then.
	measure the wire exactly using the wire	However, because the wires were
	since the wire kept moving, and the	wiggly and curvy, we had to
	measurements depended on our view	estimate the measurements. The
	of the ruler, which would make the	cuttings were also not precise since
	measurements even more unstable.	we couldn’t mark the wires on
		where exactly to cut.




Inconsistency of	There was an inconsistent use of	Next time, the experiments should
making the wires	materials throughout the experiment,	think the steps through and cut
conductive	one of which was the rubbing of the	them into one whole 150cm wire,
	wires with the sandpaper, which was a	and rub the entire thing with the
	crucial step as it would result in better	same sandpaper in the same time,
	and consistent reading. However,	but the same person, all at once, so
	because the experimenters did not	the wires have the same amount of
	think this through, we cut the wire from	conductivity even when they are
	the rolled coil one by one and rubbed	later cut into smaller pieces of
	them separately, which means some of	different lengths.
	the wires were rubbed in more areas
	than others, or rubbed more evenly
	than others, or the other many possible
	errors. This was what resulted in the
	large error bars of those 2 datas
	mentioned previously.

BIBLIOGRAPHY

“Potential Difference” BBC – GCSE Bitesize. BBC, Sep 15. 2006. Web. May 8. 2018. [http:// bbc.co.uk/schools/gcsebitesize/design/electronics/calculationsrev1.shtml]
“Resistance” Physics Classroom. The Physics Classroom, n.d. Web. May 8. 2018. [http:// physicsclassroom.com/class/circuits/Lesson-3/Resistance]
“Resistance and Resistivity” N.p., n.d. Web. May 8. 2018. [http://resources.schoolscience.co.uk/CDA/16plus/copelech2pg1.html]
“Resistance: Chapter 1 – Basic Concepts of Electricity” All About Circuits. EETech Media, LLC, n.d. Web. May 8. 2018. [https://www.allaboutcircuits.com/textbook/direct-current/chpt-1/resistance/]

Poem From Snowbound Explained
Capacitance & Resistance
Drake’s Equation Explained
Lab Explained: Ohm's Law Lab
What is Electrical Resistance?

excellent work. thank you ever so much.

Glowing regards, Shan

Data analysis?

indeed a great help

Tensile Testing (lite)

Structural materials are required to withstand a variety of applied loads in use. Understanding how these materials respond to applied loads is vital for informed materials selection. Here you can investigate how materials behave under tensile loading (loads applied along the length of a material to cause stretching).

This is only the LITE version, the full version (wtih all materials) is availabe via log-in. Press GO to launch the experiment!

Application
Quick Guide
Full Instructions

What is ‘Tensile Testing’?

The ‘tensile’ properties of a material describe its most basic mechanical behaviour – how much does a material stretch when it is pulled and how much of the stretching is permanent? ‘Tensile Testing’ is the process of measuring a material’s tensile properties.

Why are tensile properties important?

Understanding of tensile properties is vital for any application that uses materials structurally, i.e. to withstand or apply force. The range of uses this covers is enormous. Strong and stiff structures are used in vehicles (cycles, cars, trains, aeroplanes, spacecraft), bridges and buildings, sports equipment and bio-implants (e.g. hip joint replacements). Flexible materials are also used in many of these applications. Thin but robust materials are used in touchscreens. Hard materials are used in machines and robots that process and shape other materials and as durable coatings that improve the performance and lifetime of aerospace and bio-implant components. Elastic materials can be stretched enormously before any permanent change is made and are used in springs and high performance fabrics. And it’s not just how a component is used – many manufacturing processes involve changing a component’s shape or response to applied forces, e.g. extrusion to make tubes, beams and bottles; drawing to make springs or wires; or forging and rolling to shape and harden metals.

Use this experiment to find out more!

Download the file below for the quick guide for the Tensile Testing experiment (requires login) or follow these brief instructions:

To select a sample:

Click the lower jaw to go to the sample view.
Open the calliper jaws, drag a sample of choice between the jaw and fully close the jaws around it. (In this LITE version you can only select one of the samples).
Use the Vernier scale to measure the sample width.
Click the sample held in the callipers to use it in the tensile testing machine.
Or open the callipers, return the sample to its original position and choose another sample. (Only available in the full version).

To set the strain increment:

Click the Set button (display starts to flash).
Use the keypad and the Del button to enter the desired Step value.
Click the Set button again (display stops flashing).

To apply strain to samples:

Set the strain increment value as described above.
Click the up arrow to increase the applied strain by the Step increment value.
Click the down arrow to decrease the applied strain by the Step increment value.
Measure (and record) the applied load (force) using the needles on the Load dial.
Turn off the strain control unit and click on the lower sample holder to select a new sample.

Download the file below for full instructions for the Tensile Testing experiment (requires login).

Structural materials are required to withstand a variety of applied loads in use. Understanding how these materials respond to the applied loads is vital for informed materials selection. Here we investigate how materials behave under tensile loading (loads applied along the length of a material to cause stretching).

The Tensile Test experiment allows a number of mechanical tests to be performed on materials, including:

Determination of full stress-strain curve to fracture, using either ‘engineering’ or ‘true’ value
Observation of elastic behaviour and calculation of Young’s modulus
Observation of the onset of plastic behaviour and permanent deformation
Calculation of moduli of resilience and toughness
Calculation of strain energy in a system
Calculation of work done in deforming a sample

Download the file below for activities for the Tensile Testing experiment (requires login).

QUICK ACTIVITIES: 9 quick activities to try
ACTIVITY 1: Elastic deformation
ACTIVITY 2: Plastic deformation
ACTIVITY 3: Fracture

(Available as separate downloads or all activities)

*NEW* Now also available in editable Microsoft Word format

We have also provided a spreadsheet file to allow you to enter your SAMPLE WIDTH, STRAIN and APPLIED LOAD data and obtain stress-strain plots. (HINT: to investigate the general form of stress-strain curves with younger students, use a default sample width of, say, 7 mm)

Watch the video above and download the file below for the background science behind the Tensile Testing experiment (requires log in).

Ohm's Law

Ohm's law is a fundamental equation that shows how voltage, electrical current and electrical resistance are related in simple conductors such as resistors. This experiments allows you to explore Ohm's law and how the coloured bands on resistors codes their resistance. In doing this you will also learn how to use a power supply and 'digital multimeters'.

Press GO to launch the experiment!

Ohm’s law

Voltage , current and resistance are the most fundamental quantities for describing the flow of electricity . Ohm’s law shows how these three quantities are related and so is a powerful way of understanding the basic nature of electricity.

This is relevant to vast areas of technology today, including national electricity grids, power generation, design of all electronic devices and all electronic circuits, heating, electrical safety and understanding of natural phenomena such as lightning. This experiment will allow you to explore Ohm’s law by making measurements of voltage, current and resistance.

Resistors are the simplest and most commonly used electronic component and almost all electronic circuits contain them. They can be used to change the properties of any circuit they are part of, such as current flow , how voltage is distributed across components, the speed of a circuit , the amount of amplification from a circuit, the response of a sensor or the amount of electrical heating from a circuit.

The simplest resistors are made of a thin film or wound wire of carbon or metal . They usually have a series of coloured bands that represents both their target resistance value and how much the actual value might vary from this (the ‘ tolerance ’). This experiment lets you practise selecting the appropriate colour bands on a resistor to achieve a certain resistance value.

Digital Multimeters

Digital multimeters (DMMs) are versatile pieces of equipment commonly found in electronics, physics and engineering labs. In this experiment you’ll learn how to use a DMM to measure voltage , current and resistance . You’ll see this piece of equipment in many other FlashyScience experiments!

Download the file below for the quick guide for the Ohm's Law experiment (requires login) or follow these brief instructions:

To measure resistance:

On the right-hand Digital Multimeter (DMM), rotate the switch to resistance measurement.
Click and drag the clips on the wires attached to the right-hand DMM so that they snap to the wires either side of the resistor (make sure the power supply is turned off).
Note the resistance value shown on the DMM screen.

To change the resistor:

Click the resistor you wish to change to move to the Selection screen.
Click on the colour band you wish to change.
Click on the palette colour you wish to select.
Click on the resistor wire to return to the main screen.

To use voltage and current:

Turn on the power supply (right hand side of screen) and turn the dial to set the voltage.
To measure current through the resistor – turn the left-hand DMM dial to DC current.
To measure the voltage across the resistor – turn the right-hand DMM dial to DC voltage.
NOTE: in this experiment the power supply voltage is also shown directly on its display.

Download the file below for full instructions for the Ohm's Law experiment (requires log in).

Download the files below for activities for the Ohm's Law experiment (requires login).

ACTIVITY 1: Investigate what the different coloured bands on resistors mean
ACTIVITY 2: Learn how to use a DMM to measure electrical resistance
ACTIVITY 3: Explore the effect of the tolerance band (band 4) on resistors
ACTIVITY 4: Explore the statistics of resistance values from resistors with the same band colour coding
ACTIVITY 5: Investigate Ohm’s law by measurement of voltage and current with a resistor
ACTIVITY 6: Investigate Ohm’s law by measurement of current for different resistors with a fixed voltage
ACTIVITY 7: Investigate Ohm’s law by measurement of voltage for different resistors with a constant current
ACTIVITY 8: Investigate the power consumption due to electricity flowing in a single resistor
ACTIVITY 9: Investigate the power consumption due to electricity flowing through different resistances

Download the file below for the background science behind the Ohm's Law experiment (requires log in).

Free-fall due to Gravity

Gravity is a fundamental force in nature, without which we would not have galaxies, stars, the Earth, oceans, life on Earth... or golf. This experiment allows you to measure the acceleration due to gravity by measuring the time taken for a ball to fall through different heights. You can choose between two ways of timing the free fall, and you can even travel through space to measure the strength of gravity on different objects of the Solar system!

It is safe to say that gravity is important to us! Without gravity there would be no life on Earth and, in fact, without gravity, the Earth would never have existed.

Gravity is responsible for stars forming in the first place, keeping the Sun from exploding from the heat it generates, and for the structure of galaxies. It also keeps the Earth in orbit around the Sun, keeps our atmosphere and oceans in place and means we don’t float off into space. Gravity even allows plants to detect which way is ‘up’ so they send their roots and shoots in the right directions. You can see more at this NASA web page .

So, why does it matter that we know how strong gravity is?

Well, for lots of reasons.

The strength of gravity is essential to know in Civil Engineering projects such as design of buildings and bridges so we can calculate the stresses materials are under .

Aircraft and space rocket designers must know the strength of gravity that must be overcome and satellite technology is based upon a certain strength of gravity to maintain orbits at particular heights above the Earth.

Hydroelectric power generation also relies on gravitational potential energy, either through energy ‘storage’ in dams or from the water flow or tides in rivers or oceans.

Our quality of life would be very different too. Most sports rely on gravity (we’re not counting chess as a sport here!) and gravity even keeps food in a saucepan while it cooks!

Download the file below for the quick guide for the Free-fall due to Gravity experiment (requires login) or follow these brief instructions:

Choose between using a Pressure Pad sensor and Light Gate sensors using switch on side of timer.
Click and drag the electromagnet
Read the height of the ball on the electromagnet using the magnified view of the ruler
Press the Start/Reset button to release the ball from the electromagnet
Read the time (from the timer) for the ball to drop to the pressure pad
Press the Start/Reset button to return the ball to the electromagnet and reset the timer to zero
Click and drag the electromagnet and both light gates to adjust their height on the ruler but ensure the separation of the electromagnet and first light gate is constant throughout your experiment
Measure the distance between light gates using the magnified view of the ruler
Read the time for the ball to fall between the light gates

Measured Earth’s gravity? Click on the poster to explore gravity elsewhere in the Solar System too!

Download the file below for full instructions for the Free-fall due to Gravity experiment (requires log in).

Download the files below for activities for the Free-fall due to Gravity experiment (requires login).

ACTIVITY 1: Measurement of g using pressure pad sensor
ACTIVITY 2: Measurement of g using light gate sensors
ACTIVITY 3: Travel the Solar System!
ACTIVITY 4: Uncertainty in g based on uncertainty in individual measurement

Download the file below for the background science behind the Free-fall due to Gravity experiment (requires log in).

Radioactivity

Radioactive materials are used by us in lots of ways. This experiment allows you to explore alpha, beta and gamma radiation and how they are absorbed by various materials. You can also measure the change in radioactive signal with distance from the radiation source and even time travel to measure the halflife of radioactive decay for different elements!

Radioactive elements (radionuclides or radioactive isotopes) produce high energy particles and are used in a huge range of applications. Most people know about nuclear power , which converts the energy of radiation from uranium-238 or plutonium-239 into heat and then electrical power, even in small-scale form for remote applications (e.g. spacecraft). There are far more widespread uses all around us though.

Radionuclides are used in many medicinal applications . They can be used as tracers to follow fluid flow inside the body by detecting the radionuclide emitted radiation (e.g. technetium-99, thallium-201, iodine-131 and sodium-24). Medical imaging can use radioactive elements that naturally collect in particular parts of the body and image the radioactive emission. For example, iodine-131 is used to image the thyroid and other isotopes can be used for other organs, such as bones, heart, liver and lungs. Larger doses of the radionuclides (e.g. cobalt-60) are used to create a targeted radiotherapy treatment of cancer in these organs. It is even possible to detect the presence of Heliobacter pylori (an unwanted bacterium that can be in stomachs) with a simple breath test that uses carbon-14.

You may have radioactive materials in your home, school or workplace. Smoke detectors use alpha radiation from americium-241 to ionise smoke particles for detection. Glow-in-the-dark inks on clocks, watches and emergency signs that convert radioactive particle energy from promethium-147 into light.

You may also have food that has been treated with radiation. Many foods (including tomatoes, mushrooms, berries, cereals, eggs, fish and some meat products) are irradiated with gamma rays from cobalt-60 to kill micro-organisms and improve the food’s shelf life (without making the food radioactive!). Similarly, gamma radiation from caesium-137 is used to sterilise medical products such as syringes, heart valves, surgical instruments and contact lens solutions.

Radioactive elements are used in industry too. For example, the absorption of different types of radiation mean it can be used to monitor the thickness of manufactured components and sheets. Radionuclides are also used for detecting leaks from pipes , the direction of underground pipes and waste dispersal in the environment. Radioactive sources are also used in industrial imaging , with the sample placed between the radiation source and a detector. Certain isotopes are used as chemicals in order to trace chemical reaction routes , e.g. carbon-14 in photosynthesis. Similar approaches are used in biology to test when proteins undergo important ‘ phosphorylation ’ reactions (using phosphorus-32) to learn when their function is activated by other proteins or small chemicals.

Radioactive elements can also be used for historical dating of objects, e.g. carbon-14 dating for estimating the age of organic matter and uranium-238 for rocks. Similarly, radioactive decay from vintage drinks such as wine can be used to prove their age, since radionuclides were released into the atmosphere by nuclear explosion tests after World War II and are present in all food and drink produced since then.

With so many uses, it’s no wonder that radioactive decay is an important aspect of science and engineering!

Download the file below for the quick guide for the Radioactivity experiment (requires login) or follow these brief instructions:

Select the radiation source:

Click on the Source holder.
Click on one of the radiation sources in the tray and then in the holder.

Detecting radiation:

Click the power switch on the Geiger-Müller counter .
Read the needle position on the dial to measure level of radiation.

Changing the filter material and thickness:

Click on the filter holder.
Click on the material of choice to increase its thickness in the holder by 1 mm.
Click on the material in the holder to reduce its thickness by 1 mm.
Measure the filter thickness using the markings inside the holder.

Change the source-detector separation:

Click and drag the holder mount to move it along the ruler.
Measure the mount’s position using the magnified ruler view seen while clicked on the holder mount.

Time travel!

Move time forward by one minute, hour, day, month or year by clicking on the appropriate value on the clock .

Download the file below for full instructions for the Radioactivity experiment (requires log in).

Download the file below for activities for the Radioactivity experiment (requires login).

ACTIVITY 1: Radioactive half-life… and time travel! (used in GCSE Physics)
ACTIVITY 2: Inverse square law (used in A-level Physics)
ACTIVITY 3: Which materials absorb different types of radiation?
ACTIVITY 4: Radiation absorption strength
ACTIVITY 5: Alpha radiation (advanced experiment)
ACTIVITY 6: Mixed radiation sources

Or see if you can do some of the following:

Measure the half-life of different sources (GCSE)
Measure how detected gamma radiation varies with source-detector separation
Find out how alpha, beta and gamma radiation is absorbed by various materials
Explore multi-decay type radioactive sources

Download the file below for the background science behind the Radioactivity experiment (requires log in).

Resistivity of a Wire

The electrical resistivity of a wire tells us how well the wire material conducts electricity. This is crucial information for any application that involves conducting electricity, including wind turbines, electric vehicles, household electrical goods and computers. Here you can measure the resistivity of wires of different materials and widths, and consider which would be best suited for conducting electricity.

Electronic materials are crucial to our life today , and electrical ‘resistivity’ tells us how good or poor a material is at conducting electricity.

We use materials with low electrical resistivity to transmit electrical power from generators, across grid distribution networks , and to homes and workplaces for use . Designers of electrical devices rely on knowing the resistivity of wire used in order to calculate the resistance of components.

These devices range in size from enormous machines such as wind turbines or industrial lifting equipment ; motors or engines in electric vehicles and all-new electric aircraft ; consumer products such as washing machines, hair dryers and ovens ; and the nanoscale components within the computer chips found in smart devices, laptops, and mobile phones .

In fact, modern computing is based on controlling the resistivity of semiconductor materials in a type of transistor (known as ‘field effect transistors’ using ‘CMOS’ technology).

Measuring electrical resistivity helps us to understand the properties of materials, to monitor manufacturing processes, and to select the best material for an application.

Download the file below for the quick guide for the Resistivity of a Wire experiment (requires login) or follow these brief instructions:

Click on the right hand wire post to move to the Select Wire screen.
Open the micrometer by dragging the thumbwheel down.
Choose a material and drag the unlabelled wire into the micrometer.
Close the micrometer and measure the wire's width.
Click on the wire while it's in the micrometer to return to the main screen .
Click on the switch to turn it on.
Measure voltage and current for a variety of contact positions on the wire.
Calculate resistance for each contact position.
Plot resistance vs contact position and calculate the gradient of a line of best fit.
Multiply the line's gradient by the wire's cross-sectional area to obtain the wire's electrical resistivity.

Download the file below for full instructions for the Resistivity of a Wire experiment (requires log in).

Download the file below for activities for the Resitivity of a Wire experiment (requires login).

QUICK ACTIVITIES: 5 quick activities to try
ACTIVITY 1: Different wire lengths

(Available as separate downloads or all activities)

Download the file below for the background science behind the Resitivity of a Wire experiment (requires log in).

Hooke's Law

Hooke's law describes how springs respond to having forces applied. This experiment allows you to apply force using weights and measure how springs of different stiffness extend in response. You can calculate the stored elastic potential energy in the springs and even go to different parts of the Solar System to see how changing the strength of gravity changes the weight applied to the springs!

Stretching – the truth!

You may wonder why we study springs and why questions about stretching springs appear on exams. Sure, springs are used in the world, but are they really so important? Why is it important to know how springs stretch when they are pulled?

Well, first, springs are incredibly useful . When made from elastic materials, such as most metals, springs stretch when pulled and return to their original size when released . They can also be compressed and, again, return to their original size when released. The stretching or compression stores energy that is then returned when the spring is released. This energy storage and return is the key reason springs are useful. Springs use this capability in all sorts of applications, including in high tech areas such as automotive, industrial tools and robotics, to more everyday items such as trampolines, mattresses, children’s play equipment, door handles and retractable pens.

The second reason is that the way that springs respond to force being applied to them (i.e. being pulled or mass added to one end of them) is identical to how materials in general behave. If materials are pulled, then they stretch. The coiled shape of a spring, though, means that the ends tend to move large distances compared to a regular shape of the same material (e.g. a simple rod). This means that studying what happens to springs when they are pulled allows simple measurements to be performed that give us understanding of how all materials behave when they are pulled. Materials behave this way in any application where they have force applied to them, e.g. in construction, vehicles, heart valves, body implants, plants, rocks, furniture, tools, footwear – the list goes on and on. And don’t forget this includes your body too!

Download the file below for the quick guide for the Hooke's Law experiment (requires login) or follow these brief instructions:

Click on 50 g or 100 g masses to add them to the mass holder.
Click on the ruler to go to a zoomed view (centimetre scale).
Click on the masses on the holder to move them back to their boxes.
To change to a different spring:
Remove all mass from the holder.
Click on the spring.
Select from Low, Medium, High or Unknown Stiffness.
Click again on the spring to return to main screen.

5. To change to a different part of the Solar System:

Click on the poster to choose where to do the experiment.

6. Click the Information button to see the controls.

Use this experiment to:

Test Hooke’s law.
Measure spring constants.
Test the ‘limit of proportionality’ for springs.
Calculate the stored energy of a spring.
See how different strengths of gravity affect the weight added to a spring.

Download the file below for full instructions for the Hooke's Law experiment (requires log in).

Download the files below for activities and associated worksheets for the Hooke's Law experiment (requires login).

ACTIVITY 1: Testing Hooke’s law
ACTIVITY 2: Measurement of the stiffness of a spring
ACTIVITY 3: Energy stored in a spring
ACTIVITY 4: Limit of proportionality of a spring
ACTIVITY 5: Travel the Solar System!

Download the file below for the background science behind the Hooke's Law experiment (requires log in).

Specific Heat Capacity: Solids

Specific heat capacity of solids is important to understand in lots of applications that deal with heat energy and changes in temperature. This experiment allows you to control the electrical heating power applied to a choice of six different materials and measure the rate at which the sample temperature changes. You can then calculate the specific heat capacity of the chosen material. Compare the different materials, investigate the effect of having thermally insulated or uninsulated samples, and see if different heating powers change the measurements.

There are lots of ways that we use materials that see them change temperature. Some examples include heating systems in buildings (especially storage heaters ), simple household appliances such as an iron or an oven , combustion engines in cars, jet engines in aircraft, high speed machines such as drills, and industrial furnaces ; however, examples also include applications where the temperature is reduced, for example in refrigerators , freezers and heat sinks , which are used to help cool another component.

A change in a material’s temperature will also result in a change in its heat energy . Different materials, however, will have a different change in heat energy for a given change in temperature.

The material's property we use to show this difference is called specific heat capacity . This property is key to allowing us to understand how components will perform in thermal applications and help us to choose the most appropriate material. If you go to study Physics or Engineering at university you will probably also learn how specific heat capacity values depend on a material’s types of atom, atomic bonding and electrical properties.

Download the file below for the quick guide for the Specific Heat Capacity: Solids experiment (requires login).

Download the file below for full instructions for the Specific Heat Capacity: Solids experiment (requires log in).

Download the files below for activities and associated worksheets for the Specific Heat Capacity: Solids experiment (requires login).

ACTIVITY 1: Measurement of specific heat capacity of a material
ACTIVITY 2: Comparison of specific heat capacity for different materials
ACTIVITY 3: Measurement of specific heat capacity using different heating powers
ACTIVITY 4: Effect of insulation on measuring specific heat capacity

(Available as separate downloads or all activities/all worksheets)

Download the file below for the background science behind the Specific Heat Capacity: Solids experiment (requires log in).

Acceleration and Force

Understanding the relationship between force, acceleration and mass is key to starting to understand the physics of changing motion. This experiment allows you to change the mass of a tabletop car and the force applied to it before timing how long it takes the car to move various distances. Analysis of your results will allow you to see the relationship between acceleration and force.

The FlashyScience Acceleration and Force experiment might use a toy car on a table top but the science you can learn from it helps us to understand the world around us, to design all sorts of new vehicles and machines, and even to understand our bodies better.

At the largest of scales, knowing the huge forces involved with galaxies, stars and planets show us how these huge objects move and even how they form. We use our knowledge of force and acceleration to launch objects into space using rockets and to put satellites into stable orbits. This knowledge also allows us to calculate the acceleration of high performance cars (e.g. F1 cars) and aircraft , to design and build machines with moving parts, and to understand the forces parts of our bodies experience through an area of science called biomechanics . Force and acceleration can even be used to measure the mass of atoms and molecules through scientific techniques called mass spectrometry , and help us to understand how atoms interact in gases.

You can see that knowledge of force and acceleration is essential to lots of areas of science, engineering and our lives in general.

Download the file below for the quick guide for the Acceleration and Force experiment (requires login).

Download the file below for full instructions for the Acceleration and Force experiment (requires log in).

Download the files below for activities and associated worksheets for the Acceleration and Force experiment (requires login).

ACTIVITY 1: Investigating acceleration, F = ma (mass transfer between car and mass holder)
ACTIVITY 2: Investigating acceleration, F = ma (constant holder mass, increasing car mass)
ACTIVITY 3: Distance versus time graphs

Download the file below for the background science behind the Acceleration and Force experiment (requires log in).

Density of Solids & Liquids

Density is an 'intrinsic' property of materials and liquids, which means its value doesn't change when the amount of material or liquid changes. This experiment allows you to find the density of various materials with regular and irregular shapes, as well as several liquids, using three methods of determining mass and volume.

Density is a basic property of materials and liquids. It is important in all sorts of areas of science , engineering and medicine . Density (mass per unit volume) is related to the type of atoms within the material or liquid and how they are arranged . Changing the temperature of a solid or liquid often changes its volume , which also changes its density . Different processing treatments of materials can lock in some of these changes, resulting in materials made of the same atoms but with different densities. Many materials can be ‘ porous ’ (contain lots of holes) and being able to measure density is a simple way of finding the level of porosity of a material.

The buoyancy of a solid in a liquid depends upon the density of the solid and liquid. Ice floats in liquid water because ice molecules are more widely spaced than those in water, and so the density of ice is lower than that of water.

The density of solids and liquids is also related to a substance’s refractive index and how it interacts with X-rays. For example, your bones are denser than your muscle tissue and so absorb X-rays more; this allows medical images to be created that show the different regions inside your body.

Density is vital to the efficient design of physical objects, particularly for structural and transport applications. There is a huge demand for engineers and materials scientists to create lighter vehicles and aircraft to reduce their power requirements and help reduce our use of fossil fuels .

Download the file below for the quick guide for the Density of Solids & Liquids experiment (requires login).

Download the file below for full instructions for the Density of Solids & Liquids experiment (requires log in).

Download the files below for activities and associated worksheets for the Density of Solids & Liquids experiment (requires login).

ACTIVITY 1: Density of regularly shaped objects – cubes and rectangular cuboids
ACTIVITY 2: Density of regularly shaped objects – spheres
ACTIVITY 3: Density of irregularly shaped objects
ACTIVITY 4: Density of liquids

Download the file below for the background science behind the Density of Solids & Liquids experiment (requires log in).

Thermal Insulation

Heat is transmitted by conduction, convection or radiation. This experimental allows you to investigate thermal conduction by measuring the time for thermal energy to pass through different materials.

The thermal conductivity of materials is hugely important for how we live today.

Thermally-insulating materials are found in lots of places around the home. This includes safety items such as oven gloves or fire blankets and inside ovens and refrigerators to stop them heating or cooling the rest of your kitchen! Your hot water pipes and water heating system will probably have thermal insulation around them to stop unwanted heat loss. Houses and other buildings usually have thermal insulation around them to reduce heat loss when it is cold outside and reduce heat entering when it is very hot outside. This is important as we try to reduce CO2 emissions from energy use as part of our fight against climate change . Insulating materials are also used around industrial furnaces , in refrigerated vehicles and packages (e.g. for transporting food or medical supplies ) in aircraft to keep crew and passengers warm in the cold air, and in spacecraft to stop the insides reaching temperature extremes and protecting the spacecraft itself from burning up if it re-enters Earth’s atmosphere.

Thermally-conducting materials are also very important to heating and cooling systems, such as heating elements in kettles and furnaces, radiators , high speed industrial machines and heat-sinks found in electronic devices.

Heat conduction is also really important in many renewable energy technologies, such as solar cells (photovoltaics), which work less efficiently if they heat up, and ‘ thermoelectric generators ’ (TEGs), which are most efficient if they conduct electricity well but conduct temperature weakly.

This huge range of applications means there is a lot of research and development of materials with new thermal conduction properties. How materials conduct heat is also related to their atomic-scale structure – this means that we can learn about the materials from how they conduct heat and change their structure in order to create new properties that are better suited for particular applications.

Download the file below for the quick guide for the Thermal Insulation experiment (requires login).

Download the file below for full instructions for the Thermal Insulation experiment (requires log in).

Download the files below for activities and associated worksheets for the Thermal Insulation experiment (requires login).

ACTIVITY 1: Effect of a material as thermal insulation
ACTIVITY 2: Comparison of different materials as thermal insulation
ACTIVITY 3: Effect of material thickness on heat conduction
ACTIVITY 4: Effect of temperature difference on its rate of change (Advanced experiment)

Download the file below for the background science behind the Thermal Insulation experiment (requires log in).

Leslie Cube (IR emission)

This experiment allows you to measure the infrared emission from the four different surfaces of a Leslie cube. You can choose which surface to measure, see what happens as temperature changes, and adjust the signal strength by changing the detector position and the level of signal amplification. Advanced activities involve calculations of emissivity, how signal varies with source-detector separation, and the temperature-dependence of infrared emission.

Any object emits electromagnetic radiation due to having a temperature above absolute zero (about -273.15°C), although different surfaces emit the radiation to different levels. This might seem like a curiosity created just for lab measurements but it has lots of real-world relevance.

The hotter an object is, the stronger this thermal emission is. Objects with different temperatures emit different parts of the electromagnetic spectrum too. Objects close to room temperature (like us!) only emit infrared radiation (‘IR radiation’), which we feel as warmth. Objects at hundreds of degrees Celsius start to emit visible radiation (wavelength from 400 – 700 nm), those at thousands of degrees Celsius emit ultra-violet (UV) radiation (wavelength from 100 – 400 nm), while the hottest objects in the galaxy (e.g. regions around black holes) emit X-ray radiation (wavelengths shorter than 100 nm).

The most important aspect of thermal emission is that life on our planet would not exist without it! Our nearest star, the Sun , is so hot its IR emission reaches across over 140 million kilometres (that’s over 90 million miles) of space to warm our planet . The Sun’s visible light also allows us to see. The Earth’s ozone layer plays an important role in absorbing most of the UV light from the Sun, which would otherwise reach us at harmful levels.

Astronomers also use the thermal emission from other stars and astronomical objects to learn about how they were formed, their lifecycle, and the processes that go on within them.

Climatologists and meteorologists (scientists who study the Earth’s climate and weather) use satellites to map the IR emission of the Earth’s atmosphere and land to help predict future weather events and trends. The surface of the Earth can also be imaged to locate underground heat sources, objects and water flows .

In smaller-scale applications, surface materials are often chosen to help either cool or insulate an object by either maximising or minimising IR emission, depending on what is needed. IR emission is used in some household or industrial heaters and to measure temperature in areas such as industrial manufacturing processes and medical applications , e.g. measuring the temperature of a patient.

‘Thermal imaging’ cameras create images from IR emission for a huge range of applications, including night vision (e.g. for security systems or non-invasive imaging of wild animals), analysing heat sources in electronic circuits , industrial monitoring (e.g. web servers , aircraft engines ), and analysing the thermal efficiency of objects from miniature devices to houses .

Download the file below for the quick guide for the Leslie Cube (IR emission) experiment (requires login).

Download the file below for full instructions for the Leslie Cube (IR emission) experiment (requires log in).

Download the files below for activities and associated worksheets for the Leslie Cube (IR emission) experiment (requires login).

ACTIVITY 1: Infrared emission from different surfaces (basic)
ACTIVITY 2: Infrared emission at different surface temperatures (basic)
ACTIVITY 3: Detected infrared emission versus distance from source (advanced)
ACTIVITY 4: Measurement of emissivity of different surfaces (advanced)
ACTIVITY 5: Temperature dependence of infrared emission (advanced)

Download the file below for the background science behind the Leslie Cube (IR emission) experiment (requires log in).

Reflection and Refraction of Light

$Reflection and Refraction of Light$

Use either a prism or a hemicylinder of material to discover how light interacts with materials when it pass through of reflects off of materials. You will be able to measure the refraction index of materials along with the angle requried for total internal reflection.

We use light in all sorts of ways. You are probably using a screen that emits light to read these words now and might be in a room that is lit by artificial light from a lightbulb.

This experiment deals with how light interacts with transparent materials. The fact that you can read this is down to how transparent materials in your eyes interact with and redirect light to create images . If you wear glasses or contact lenses , you are relying on these effects even more!

In fact, there are lots of types of imaging systems that work by redirecting light. These include a wide variety of microscopes and telescopes for making the very small or very large parts of our world and universe visible to us. These work by refracting light through lenses or by reflecting light from mirrors , or a combination of both.

Light scanners use light refraction or reflection in all sorts of applications, from barcode readers to laser display systems to laser machining tools used to process materials.

Vast amounts of information are sent worldwide every minute of every day using packets of light travelling down transparent fibre optic cables. This vital technology depends on how light interacts with interfaces between two types of material. The future might see super-fast all-optical computers that use light to process information.

The way light interacts with a material can also tell us a lot about the material. Lots of scientific techniques use light to probe the nature of all sorts of materials.

The FlashyScience Reflection & Refraction of Light experiment allows you to learn about the way light behaves at surfaces and through transparent materials – this is a great starting point to understanding many of the ways we use light in the world around us!

Download the file below for the quick guide for the Reflection & Refraction of Light experiment (requires login).

Download the file below for full instructions for the Reflection and Refraction of Light experiment (requires log in).

Download the files below for activities and associated worksheets for the Reflection and Refraction of Light experiment (requires login).

ACTIVITY 1: Reflection from a surface
ACTIVITY 2: Refraction in materials: air-to-glass
ACTIVITY 3: Refraction in materials: glass-to-air
ACTIVITY 4: Transmission of light

Download the file below for the background science behind the Reflection and Refraction of Light experiment (requires log in).

Properties of waves (ripple tank)

Waves are incredibly important across science, engineering, technology, and medicine. Learning about them from waves on the surface of a liquid is a great way of starting to understand them. Here, you can change the frequency of waves on water and measure their wavelength, and then change to different liquids, use different depths of liquid, and even perform the experiment around the Solar System!

Most people are familiar with waves on the surface of water from looking at ripples created by, for example, dropping stones into the water. This might seem to have little to do with how we live but this couldn’t be further from the truth – waves are essential for our existence and there is a huge range of applications of them in our world.

Understanding waves on water Is essential for understanding important topics like coastal erosion and how to reduce it, using renewable electricity from wave poower , designing ships, and even calculating the speed of tsunami events.

We find all sorts of other waves, too, though. Light is a kind of electromagnetic wave , together with all parts of the electromagnetic spectrum, including radio waves, microwaves, infrared radiation, ultra-violet, X-rays, and even gamma rays. The range of applications from these is immense, and includes, among many other areas, optics (do you wear glasses or contact lenses?), communications , displays , sensors , telescopes and microscopes , imaging techniques , medical diagnostics and therapies , radar , cooking , heating , energy applications , and manufacturing techniques (e.g. laser-selective melting 3D printing), and all sorts of scientific methods of measurements or controlling matter, e.g. measuring the distance between atoms in a material, finding the structure of a protein molecule, or even laser-cooling and trapping of atoms.

The vibrations in materials are waves, too, and these allow us to make all sorts of musical instruments with different sounds. Sound then travels through the air and materials as a wave, and this allows us to design soundscapes and tones using acoustics . These effects also allow sonar to map below the surface of the sea, acoustic imaging to visualise underground structures, and ultrasound imaging to show us inside the human body, for example, to check the health and development of a growing foetus through to visualising damage to a bone joint.

At a larger scale, seismology uses how wave vibrations travel through the Earth to understand its structure and why events like earthquakes happen. Understanding waves then also helps us to design buildings that can withstand earthquakes. Seismology is now even being applied to other planets in the Solar System to understand their structures, too. Believe it or not, the Sun’s surface shows ripples due to pressure waves inside it, and scientists study these to learn more about what happens inside the Sun. And, within the last few years, scientists have detected gravitational waves that travel through the universe!

Zooming back to the smallest scales, atoms and subatomic particles such as electrons often behave like waves (if you continue to study science will learn more about this in the coming years). These properties have been incredibly important for us to understand fundamental physics and have given us new areas of science such as ‘ quantum mechanics ’. This helps to explain the nature of atoms, how they interact, and why different elements have such different properties – these were huge questions for humankind for centuries. Indeed, all chemistry comes from electrons having wave properties, while the electrical properties of metals, semiconductors, and insulators, as well as most magnetic properties of materials, come from the wave properties of electrons. Today, we’re seeing new technologies based on quantum mechanics, such as unbreakable codes ( cryptography ) and super-powerful ‘quantum computing' . These same wave properties of electrons lie behind crucial biological processes such as photosynthesis , without which there would be no life on Earth.

What’s great news is that waves have many common properties, whatever type they and wherever they are found.

The FlashyScience Properties of Waves experiment will help you on the first steps of the journey to understand how waves travel and can be used!

Download the file below for the quick guide for the Properties of waves (Ripple tank) experiment (requires login).

Download the file below for full instructions for the Properties of waves (Ripple tank) experiment (requires log in).

Download the files below for activities and associated worksheets for the Properties of waves (Ripple tank) experiment (requires login).

ACTIVITY 1: How wavelength changes with frequency
ACTIVITY 2: Speed of waves on water
ACTIVITY 3: Relationship between wavelength and frequency
ACTIVITY 4: Effect of water depth on surface waves
ACTIVITY 5: Waves on different liquids (advanced)
ACTIVITY 6: Effect of gravity on surface waves on liquids (advanced)

Download the file below for the background science behind the Properties of waves (Ripple tank) experiment (requires log in).

Reflection and Refraction of Light (Advanced)

$Reflection and Refraction of Light (Advanced)$

This experiment deals with how light interacts with transparent materials. You can explore the nature of the refraction of light by taking measurements using four different materials and applying Snell's law. Refraction is an important optical effect. The fact that you can read this is down to how transparent materials in your eyes refract light to create images . If you wear glasses or contact lenses , you are relying on refraction even more!

In fact, there are lots of types of imaging systems that work by refracting light. These include a wide variety of microscopes and telescopes for making the very small or very large parts of our world and universe visible to us. These work by refracting light through lenses or by reflecting light from mirrors , or a combination of both.

This experiment also allows you to investigate total internal reflection with the various materials provided. Vast amounts of information are sent worldwide every minute of every day using packets of light travelling down transparent fibre optic cables. This vital technology depends on total internal reflection of light at the interface of two types of material to direct the light with minimal loss of intensity. The future might see super-fast all-optical computers that use light to process information.

Download the file below for the quick guide for the Reflection & Refraction of Light (Advanced) experiment (requires login).

Download the file below for full instructions for the Reflection & Refraction of Light (Advanced) experiment (requires login).

Download the files below for activities and associated worksheets for the Reflection & Refraction of Light (Advanced) experiment (requires login).

ACTIVITY 1: Snell's law (calculating refraction)
ACTIVITY 2: Total internal reflection

Download the file below for the background science behind the Reflection & Refraction of Light (Advanced) experiment (requires login).

The Young Modulus (Pre-release)

Measuring the Young Modulus of a piece of wire made from steel, aluminum, copper or nylon. NOTE: This is a beta version that is currently being tested but feedback is very welcome!

Simple Harmonic Motion (Pendulum) - Early release

Simple Harmonic Motion using a Pendulum - early release.

Simple harmonic motion (SHM) is a type of oscillating motion. It is used to model many situations in real life where a mass oscillates about an equilibrium point. Early release - while the experiment is fully functional not all documents and supporting material is available just yet.

Simple harmonic motion can be seen all around us in objects and applications that improve our lives. However, it is also seen in the fundamental behaviour of molecules and materials, although this usually occurs at frequencies and length scales that require scientific instruments for us to observe them.

A child on a park swing will just be enjoying the ride, probably unaware that the swing’s movement is an example of simple harmonic motion , or SHM.

The same child might go on a larger ride, such as a Pirate Ship, at an amusement park. The ride’s designers will have used simple harmonic motion principles to calculate the frequency of the Pirate Ship, its maximum speed , and the forces involved, and use this to specify the construction materials and the electric motor that should be used.

Musical instruments often use simple harmonic motion. For example, the strings of stringed instruments such as a guitar or violin vibrate back-and-forth in a way that obeys simple harmonic motion.

Our understanding and measurement of time has been affected by simple harmonic motion. Pendulum clocks use the regular, simple harmonic motion of a pendulum mass to determine how fast the clock hands move, while this is done in quartz clocks and watches using the simple harmonic vibrations of a quartz crystal.

Shock absorbers , including those in cars, use springs in an oil that move with ‘damped’ harmonic motion to reduce vibrations and give the vehicle passengers a smoother ride.

Simple harmonic motion is important for hearing too. The cochlea in our ears is lined with hairs called stereocilia just 0.01 – 0.05 mm in length. These hairs vibrate when particular frequencies of sound are transmitted through the cochlea and give us our sense of hearing.

The electronic bonds that hold atoms together in molecules and solids create forces that try to return atoms to equilibrium positions. This results in simple harmonic motion, even at this atomic scale .

Different molecules have atoms and groups of atoms with different masses bonded in different ways (e.g., single or double bonds) that can also vibrate in different ways (e.g. three atoms bonded along a single axis can all vibrate along the axis or laterally to it). This means that molecules have different sets of vibrational frequencies that absorb light of the same frequencies, usually infrared light. Forms of infrared spectroscopy are therefore used to find what molecules are in a measured sample.

These vibrations are one of the main ways molecules and solids absorb thermal energy, and increasing the temperature of molecules or solids will increase the amplitude of their simple harmonic vibrations.

There are also some sophisticated scientific effects that show simple harmonic motion. One example is electrons at the surface of some metals. A sea of conduction electrons can form, which then acts as a single object. This sea of electrons, known as a surface plasmon , can be made to oscillate across the metal using light. The simple harmonic motion of surface plasmons is currently being developed in research labs to create high sensitivity detectors (e.g., of molecules, proteins, and bacteria), computer chips thousands of times faster than those we have today, and even improved makeup !

Download the file below for the quick guide for the Simple harmonic motion (Pendulum) experiment (requires login).

Download the file below for full instructions for the Simple harmonic motion (pendulum) experiment (requires log in).

Download the file below for the background science behind the Simple harmonic motion (pendulum) experiment (requires log in).

Earth Science

Physical Science

Social Science
Medical Science
Mathematics
Paleontology

Experiments with Resistivity

Experiments with Resistivity and Youngs Modulus.

Detailed Plan

I will do an experiment using Wire A’ all I know about this is that it has a SWG of 32. I will find the material that this wire is made out of by working out its resistivity. When I know value this I can simply look it up in the table of resistivity to find the material.

The Resistivity Equation is:

Resistance = Resistivity x Length the Wire / Cross Section Area of Wire

Symbols and Units: Resistance – R, measured in Ohms () Resistivity – , measured in Ohm Meters (m) Length – L, measured in Meters (m) Cross Section Area – A, measured in meters (m)

I will draw a graph of this equation with L/A as the x value and R as the y value to find out resistivity (which is the gradient) as I can measure length and area and I can calculate resistance as it is Voltage/Current.

the value of resistance will increase with the length of wire used

the Wires cross sectional area should be constant all the way along

To Be Kept The Same: Voltage coming from the power pack – 4V The Piece of wire used (thickness and area) Same Ammeter, Voltmeter, cables, etc…

That Will Change: The Length of the wire The Temperature of all the components (although not desired as it may alter readings)

Proposed Method

For this experiment you will need to find out the Cross section area of the wire, the length of the wire and the resistance of the wire, which you can work out by finding the current and voltage of the piece of wire at each length and applying the equation:

Resistance = Voltage / Current

So for my experiment I will change the length of my wire and at each interval record to wires thickness, the voltage and the current passing through it. I will then plot the graph of

Resistance = Resistivity x Length of the Wire Cross Section Area of Wire

So the resistivity of my wire will be the gradient of my graph. Which is calculated by the change in x value / by the change in y value.

Method 1. Collect all equipment as in apparatus list 2. Measure out around 120cm of wire to stretch across the ruler so I have reasonable excess to attach my crocodile clips too. 3. Measure the thickness of the wire using a micrometer at 3 different stages along its length to take an average in case it is uneven. I can then halve this value to find the radius and apply rules of mathematics to find the area of the wires cross section 4. Secure the wire so it is taught along the ruler using sellotape 5. Connect all wires to the power pack, ammeter, voltmeter etc making sure the components are in series or parallel depending on their function 6. Attach crocodile clips to each end of the wires and connect them to the beginning value of 1m of wire 7. Set the power pack to 4v (will not change this) 8. Record readings of both current and voltage 9. Turn power pack off for around 5 second for it too cool down 10. Move the crocodile clip up or down 10cm to the next length required 11. Repeat from step 8 until all lengths are recorded

Range of readings = 0.100m 1.000m and 1.000m 0.100m I will do repeats of any result which is wildly of the general trend of others to ensure any initial random errors.

Apparatus Required

Ammeter Range: +20 to -20, to the nearest 0.01 of a Volt Voltmeter Range: +20 to -20, to the nearest 0.01 of an Amp Micrometer Range: 0.01mm to 2.500 cm, to the nearest 0.01 of a mm Meter Ruler Range: 1mm to 1m, to the nearest mm Power Pack Range: 1 to 15 volts, to the nearest Volt (set at 4V) Crocodile Clips Sellotape Cables Wire SWG: 32, Unknown material

Safety Considerations

Before adjusting the wire to the desired legnth, leave it to cool for a few seconds to avoid being burnt

Proposed Readings

I will take a reading of both current and voltage when the wire is at lengths of 0.100, 0.200, 0.300, 0.400, 0.500, 0.600, 0.700, 0.800, 0.900 and 1.000 m and then backwards in 10 cm intervals so 1.000, 0.900, 0.800, 0.700, 0.600, 0.500, 0.400, 0.300, 0.200, and 0.100. I will then use an average of the 2 results to get an average current and voltage for each length of wire then find the resistance

Reason For Procedure

I will take these readings because as the experiment goes on the temperature of the wire will increase and this will most likely effect the resistance of the wire so I will take a reading from each measurement when the wire is hot and when the wire is cold so I can take an average and hopefully rule out a systematic error in this area.

Justification For Design

To find resistivity I will draw the graph of R= x L A In comparison to Y = MX + C This gives . Y Axis = Resistance Gradient = Resistivity X Axis = Length / Cross Section Area So my choice of variables was the length or cross section area of the wire. I have chosen to calculate L/A before plotting my graph instead of plotting L as the y axis as it prevents later calculations using the gradient and I have on simple calculation to find out my resistivity which is simply to find the gradient:

Gradient = Change in Y Change in X

Aspects of the plan based on predictions

I cannot really predict the outcome of my experiment but I will take 2 readings of voltage and current as I assume the wire will heat up and affect the readings as the experiment goes on.

A8d Preliminary Results or secondary sources

Length of wire = 0.100 m Resistance 1 = 2.13 Resistance 2 = 2.09

Resistance = Resistivity x Length the Wire Cross Section Area of Wire

Average Resistance = 2.11 Wire Thickness = 0.270 mm

So 2.11 = x 0.100 => 2.11= x 1.75 x10 5.73 x10^6

P = 2.11 = 1.06 x10^ -6 m 1.75 x10^6

Identifying Significant Sources of Error

Anything measured is a source of error

– Length of the wire – Current – Voltage – Thickness of the wire

Length Min reading 0.10 m, + or – 1mm, max error = 1% Current Min reading 0.13 Amps, + or 0.01 amps, max error = 8% Voltage Min reading 2.24 Volts, + or 0.01 volts max error = 1% Thickness Min reading 0.27mm, + or 0.01 mm, max error = 4%

Maximum equipment error = 14% (with rounding)

Proposed action to minimize errors

To prevent systematic errors whilst measuring the current and voltage, I will take 2 readings for each when the wire is cool and when it is warm and then take an average. Whist measuring the thickness of the wire I will take 3 readings from different places on the wire and then take an average.

Information taken from graph gradient intercept

Gradient = 14.5 / 13.25 x10^6 = 1.09 x10^ -6 Intercept = 0.25

RESISTIVITY = 1.09 x10^ -6 m

I found the resistivity of the wire to be 1.09 x 10^6 m by finding my gradient values (Y X, change in Y Change in X) which was 14.5 13.25 x10^6 and according to the table of resistivity (in the appendix) my wire is made out of Nichrome as its resistivity is 1.10 x10 m so I am only 0.01 out.

Supports my prediction?

My predictions were correct as the resistance of my wire did increase and the diameter and therefore cross sectional area of my wire were equal all the way along.

Evaluating Evidence

Possible sources of error

Length of the wire Current Voltage Area of the wire

Comments On Anomalous results

The readings when the length of wire was 30cm and 90cm appear to be slightly of the trend more than the others but they still follow the line of best fit pretty well.

Comments on repeat readings

My repeat readings all varied from the first readings but this was pretty constant with all the readings and was expected due to the rise in temperature of the wire as the experiment went on.

Discrepancies between expected results and experimental evidence

My experimental evidence (Preliminary Results) as shown in A8d suggested a final value of around 1.06 x10 ^6 m (as Below)

And my final value using all of my data and graph gave me an answer of 1.09 x10^ -6 m, so I think both sets of my results were very accurate.

Indication of most significant measurements

Judging by graphs line of best fit I have three values which have slight random errors, the value at 10.47 x10 ^6, 5.24 x10 ^6 and 15.56 x10 ^6 on the x axis. However the line of best fit corrects these errors as my formulae means my gradient gave me the resistivity.

My most significant source of error I think was the length of the wire as I had to use crocodile clips which are 5mm across so therefore I can only get within 5mm to my measurement

0.10m + or 5mm = 5% error

So the new total error is 18%

Estimate the error or uncertainty in all measurements

Also see above section for error calculations Length Min reading 0.10 m, + or – 5mm, max error = 5% Current Min reading 0.13 Amps, + or 0.01 amps, max error = 8% Voltage Min reading 2.24 Volts, + or 0.01 volts max error = 1% Thickness Min reading 0.27mm, + or 0.01 mm, max error = 4%

Total Error = 18%

So my resistivity has a range of: 0.89 x10^ -6 m to 1.29 x10^ -6 m

My answer of 1.09 x10^ -6 m falls virtually in the middle of these two bounds so I think my answer was reasonably accurate.

Determining Systematic and Random errors

Random errors are quite easy to spot on my graph as they do not fit the line of best fit, and although I had no huge errors, I have three values which have slight random errors, the value at 10.47 x10 ^6, 5.24 x10 ^6 and 15.56 x10 ^6 on the x axis.

Systematic errors are slightly harder to spot but all it will affect is the position of my line and this doesn’t effect my gradient, which is what gives me my value so it doesn’t make much difference.

Electrical Resistivity Measurements: a Review

January 2013
International Journal of Modern Physics Conference Series 22(10):745-756
22(10):745-756

BIKANER TECHNICAL UNIVERSITY, BIKANER (RAJASTHAN) - INDIA

Abstract and Figures

Discover the world's research

25+ million members
160+ million publication pages
2.3+ billion citations
Sang-Hoon Lee

Yasir Makki Abdul Razzaq
Int J Interact Des Manuf
Sharad Nirgude
Shyamkumar Kalpande

ACS APPL MATER INTER

Fabio Biscarini
BRAZ J PHYS

Gabriel Henrique de Faria
Lívia C. dos Passos Araújo
Gustavo P. Lopes
Alvaro A. A. de Queiroz
Kinithi M. K. Wickramaratne

Farshid Ramezanipour
Arthur Uhlir
Jr. W C Dunlap
Makoto Kuwabara
P. W. Bridgman
Walter C. Michels
J ELECTROCHEM SOC
W. Crawford Dunlap
H. F. Mataré
CONTEMP PHYS
E. P. Wohlfarth
GEOPHYS J INT
C. R. B. Lister
H. C. Montgomery
Takamichi Iida

Recruit researchers
Join for free
Login Email Tip: Most researchers use their institutional email address as their ResearchGate login Password Forgot password? Keep me logged in Log in or Continue with Google Welcome back! Please log in. Email · Hint Tip: Most researchers use their institutional email address as their ResearchGate login Password Forgot password? Keep me logged in Log in or Continue with Google No account? Sign up

Grades 6-12
School Leaders

100 Last-Day-of-School Activities Your Students Will Love!

Every product is independently selected by (obsessive) editors. Things you buy through our links may earn us a commission.

24 Shockingly Fun Electricity Experiments and Activities for Kids

Play dough circuits, LED magic wands, and more!

Examples of electricity experiments including making batteries out of dirt and creating a pencil resister.

Electricity is all around us, so we tend to take it for granted. It’s a fascinating subject for kids, though, so they’ll love these electricity experiments and activities. You may need to invest in a few simple supplies for some of these activities, but you’ll be able to reuse them for multiple activities year after year. The hands-on experience kids will get makes the extra effort worthwhile.

1. Start with an anchor chart

Static electricity is most kids’ intro to this concept, and it leads nicely into electrical energy and circuitry. These colorful anchor charts help you teach both.

Get tutorial: Anchor chart about electricity and electricity anchor chart

balloon held up to a stream of water for an electricity experiment

2. Bend water with static electricity

Most static electricity experiments are quick and easy enough for anyone to try at home. This is a great example: Charge a comb by rubbing it against your head, then use it to “bend” a stream of water from a faucet.

Get tutorial: Water balloon experiment

spoon by salt and pepper for an electricity experiment

3. Separate salt and pepper using a magic spoon

This static electricity experiment works because pepper is lighter than salt, which makes it quicker to jump to the electrically charged plastic spoon. So cool!

Get tutorial: Salt and pepper experiment

child looking at a bubble on the counter with a balloon for an electricity experiment

4. Move a bubble using a balloon

Balloons are a fun way to teach about static electricity. Combine them with bubbles for a hands-on activity students will really love.

Get tutorial: Bubble experiment

a balloon near a craft butterfly for an electricity experiment

5. Flap a (paper) butterfly’s wings

Speaking of balloons, try using them to help a butterfly flap its tissue paper wings. Little ones’ faces light up when they see the butterfly come to life.

Get tutorial: Butterfly wing experiment

balloon next to goo for an electricity expriment

6. Make jumping goop with static electricity

Kick your static electricity experiments up a notch by mixing a batch of cornstarch “goop,” then making it “jump” toward a balloon. Amazing!

Get tutorial: Jumping goop experiment

play dough heart with wires made into a circuit

7. Assemble circuits from play dough

When you’re ready to explore electrical energy, start with play dough circuits. You’ll need a battery box and mini LED lights. Mix up your own batches of insulating and conducting play dough using the info at the link.

Get tutorial: Play dough circuit experiment

Buy it: Battery box and clear LED lights at Amazon

8. Create a classic potato clock

A potato clock is an impressive way to kick off or end a unit on electricity. Your students will never look at potatoes the same way again.

Buy it: Potato Clock experiment kit

cup of water and two electrical circuits for water electricity experiment

9. Find out if water conducts electricity

We’re always telling kids to get out of the water at the first sign of a lightning storm, so use this demo to help them understand why. You’ll need alligator clip wires, mini LED bulbs, and button cell batteries.

Get tutorial: Water electricity experiment

Buy it: Alligator clip wires , mini LED bulbs , and button cell batteries at Amazon

wands with lit tops of green, blue red and white for an electricity experiment

10. Whip up wizard wands

Lumos! If your kids are fascinated by Harry Potter and the world of magic, they’ll love this electricity project that turns ordinary sticks into light-up wands! Learn how it’s done at the link.

Get tutorial: Wizard wand project

example of a steady hand game you can make with wires and blocks

11. Play a DIY steady-hand game

Electricity experiments like this one are perfect for exploring the idea of open and closed circuits. Plus, kids will have so much fun playing with them.

Get tutorial: Steady-hand game

a hand holding copper penny above water with wires going into the wire

12. Copper-plate coins using electricity

We all know electricity lights up a room and powers phones, computers, and even cars. But what else can it do? This electroplating experiment is a real jaw-dropper.

Get tutorial: Copper plate coins experiment

index card flashlight for an electricity experiment

13. Create an index card flashlight

This DIY flashlight really turns on and off! It only takes index cards, aluminum foil, mini LED bulbs, an button cell batteries.

Get tutorial: Index card flashlight

Buy it: Mini LED bulbs and button cell batteries at Amazon

batteries with wires that look like dancers

14. Twirl some homopolar dancers

These sweet little twirling dancers are a fantastic demonstration of a homopolar motor. In addition to basic AA batteries, you’ll need neodymium magnets and copper wire.

Get tutorial: Homopolar dancers

Buy it: Neodymium magnets and copper wire at Amazon

lumps of play dough to conduct electricity in an electricity experiment

15. Build multiple circuits

Create more than one circuit using play dough to create a series. The positive leg of the LED is near the battery terminal. Since the battery can only push the electricity one way, you can create a circuit of two or more to create a larger circuit.

Get tutorial: Series circuit experiment

coins stacked in a tower with an l e d light

16. Make a coin battery

Use a stack of coins (the more coins you use, the more electricity produced) to make a battery.

Get tutorial: Coin battery

battery with copper wire wrapped around a nail for an electricity experiment

17. Make an electromagnet

Make an electromagnet, or a magnet that uses an electric field, by wrapping wire around an iron nail and running current through the wire. An electric field is created around the nail and, sometimes, the nail will stay magnetized even when the coil is removed.

Get tutorial: Electromagnet project

pencil resister with red and green alligator clips

18. Create a pencil resister

Learn about how resisters control the amount of electricity that flows through a circuit. Use pencils (a great way to use those old stubby pencils that are sharpened at both ends) as part of the circuit, and watch the brightness of the build change when the resistance in the circuit changes.

Get tutorial: Pencil resister project

Buy it: AA batteries , battery holder , LED light bulbs , and alligator clips at Amazon

household objects on a tray, key, cork, paper, paperclip for an electricity experiment

19. Find out what conducts electricity

Figure out what objects are made of material that conducts or does not conduct electricity. Collect common objects such as a key, chalk, wood, and/or candle. Then, test each object by putting it between a battery and a light bulb and touching foil to the base of the bulb. If the bulb lights up, the object conducts electricity!

Get tutorial: What conducts electricity? experiment

Buy it: AA batteries and LED light bulbs at Amazon

spiral of black paint on paper for electricity experiment

20. Create electric paint

Use electric paint to create a circuit and light up a painting with batteries and LEDs. You will need a multimeter for this project (here’s how to use a multimeter ).

Get tutorial: Electric paint project

Buy it: Multimeter , electric paint , 9-volt batteries , LED light bulbs , and alligator clips at Amazon

21. Create an electromagnetic train

Show the connection between electricity and magnetism by creating a train with a battery and some neodymium magnets. One note: This is a project for older students who have close adult supervision, as neodymium magnets are very strong.

Get tutorial: Electromagnetic train project

Buy it: Neodymium magnets at Amazon

materials to make a soda can electroscope tin foil scissors soda can

22. Create an electroscope with a soda can

An electroscope detects the presence of an electronic charge. Create a basic but effective electroscope with a soda can, insulation tape, aluminum foil, and a Styrofoam cup. Put it near various surfaces and see what happens.

Get tutorial: Soda Can Electroscope

dirt with nails in it for a dirt battery

23. Turn dirt into a battery

Electricity can even conduct in dirt. Create a dirt battery with galvanized steel screws (very important), an ice cube tray, copper wires, and soil. Make it more interesting by putting lemon juice or vinegar in the dirt.

Get tutorial: Dirt Battery Experiment

Buy it: Copper wire and galvanized screws at Amazon

lemon with coins in it to create a lemon battery

24. Lemon battery

Use a lemon to create a battery with coins and a multimeter. It’s a great way to show students how literally anything can be a conductor of electricity.

Get tutorial: A Simple Lemon Battery

Buy it: Multimeter at Amazon

Love these electricity experiments and activities? Check out Easy Science Experiments Using Materials You Already Have On Hand .

Plus check out turn muggles into wizards with harry potter science experiments ..

Try these fun electricity experiments and activities for kids. Make an index card flashlight, LED magic wand, or play dough circuits!

Easy science experiments including a "naked" egg and "leakproof" bag

72 Easy Science Experiments Using Materials You Already Have On Hand

Because science doesn't have to be complicated. Continue Reading

Observations of electrical resistivity tomography and groundwater level under an irrigated terraced paddy field in northern Taiwan

Published: 13 June 2024

Cite this article

Qun-Zhan Huang ORCID: orcid.org/0000-0002-1890-2323 1 ,
Shao-Yiu Hsu ORCID: orcid.org/0000-0002-6666-4665 1 ,
Jie Hu 1 &
Yu-Chuan Chang 2

Explore all metrics

In an irrigated paddy terraced field, subsurface return flow within the plots potentially occurs as long-term ponding water may lead to shallow groundwater uplift to the soil surface. However, subsurface water remains hidden from direct observations. Using an irrigated paddy terraced field located on Ewei Mountain, Taipei, as the study area, we investigated subsurface water during both irrigation and non-irrigation periods by employing electrical resistivity tomography (ERT) and monitoring the groundwater level in wells. The ERT results provided two-dimensional (2D) electrical resistivity sections. The sections show that the subsurface moisture was higher during the irrigation period than during the non-irrigation period. The ERT results indicate the possible location of the shallow groundwater layer and the presence of preferential flows beneath the embankments. Information gathered from rock cores, groundwater level records, and ERT was used to delineate the boundary between the topsoil layer and other geological materials. Rainfall and irrigation can dramatically increase the groundwater table, although it hardly exceeds this boundary. Our findings suggest that considering the subsurface return flow within plots may not be essential in this study area. The investigation with ERT helped assess whether the subsurface return flow needs to be considered in the irrigation management of a terraced paddy field.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price includes VAT (Russian Federation)

Instant access to the full article PDF.

Rent this article via DeepDyve

Institutional subscriptions

Adachi S (2007) Agricultural technologies of terraced rice cultivation in the Ailao Mountains, Yunnan, China. Asian African Area Studies 6(2):173–196. https://doi.org/10.14956/asafas.6.173

Article Google Scholar

Anderson MG, Burt TP (1990) Process studies in hillslope hydrology. John Wiley and Sons Ltd., Chichester

Google Scholar

Archie GE (1942) The electrical resistivity log as an aid in determining some reservoir characteristics. Trans AIME 146(01):54–62. https://doi.org/10.2118/942054-G

Bernabé Y (1995) The transport properties of networks of cracks and pores. J Geophys Res: Solid Earth 100(B3):4231–4241. https://doi.org/10.1029/94JB02986

Besson A, Cousin I, Bourennane H, Nicoullaud B, Pasquier C, Richard G et al (2010) The spatial and temporal organization of soil water at the field scale as described by electrical resistivity measurements. Eur J Soil Sci 61(1):120–132. https://doi.org/10.1111/j.1365-2389.2009.01211.x

Camporese M, Paniconi C, Putti M, McDonnell JJ (2019) Fill and spill hillslope runoff representation with a richards equation-based model. Water Resour Res 55(11):8445–8462. https://doi.org/10.1029/2019WR025726

Chen R-S (2008) Adaptability study on USLE for soil erosion of terraced paddy field. Retrieved from Council of Agriculture, Executive Yuan, R.O.C.

Chen R-S (2009) Comparison of soil erosion before and after terraced paddy field fallow. Retrieved from Council of Agriculture, Executive Yuan, R.O.C.

Chen S-K, Liu CW, Huang H-C (2002) Analysis of water movement in paddy rice fields (II) simulation studies. J Hydrol 268(1):259–271. https://doi.org/10.1016/S0022-1694(02)00180-4

Chen B, Garré S, Liu H, Yan C, Liu E, Gong D, Mei X (2019) Two-dimensional monitoring of soil water content in fields with plastic mulching using electrical resistivity tomography. Comput Electron Agric 159:84–91. https://doi.org/10.1016/j.compag.2019.02.028

Chukwudi C (2011) Geoelectrical studies for estimating aquifer hydraulic properties in Enugu State. Nigeria Int J Phys Sci 6(14):3319–3329. https://doi.org/10.5897/IJPS10.274

Choo H, Kim J, Lee W, Lee C (2016) Relationship between hydraulic conductivity and formation factor of coarse-grained soils as a function of particle size. J Appl Geophys 127:91–101. https://doi.org/10.1016/j.jappgeo.2016.02.013

Doyoro YG, Chang P-Y, Puntu JM (2021) Uncertainty of the 2D Resistivity Survey on the Subsurface Cavities. Appl Sci 11(7):3143. https://doi.org/10.3390/app11073143

Article CAS Google Scholar

Fitriyah A, Fatikhunnada A, Okura F, Nugroho BDA, Kato T (2019) Analysis of the drought mitigated mechanism in terraced paddy fields using CWSI and TVDI indices and hydrological monitoring. Sustainability 11(24):6897. https://doi.org/10.3390/su11246897

Garré S, Günther T, Diels J, Vanderborght J (2012) Evaluating experimental design of ERT for soil moisture monitoring in contour hedgerow intercropping systems. Vadose Zone J. https://doi.org/10.2136/vzj2011.0186

Glover PW, Walker E (2009) Grain-size to effective pore-size transformation derived from electrokinetic theory. Geophysics 74(1):E17–E29. https://doi.org/10.1190/1.3033217

Gouet-Kaplan M, Arye G, Berkowitz B (2012) Interplay between resident and infiltrating water: estimates from transient water flow and solute transport. J Hydrol 458:40–50. https://doi.org/10.1016/j.jhydrol.2012.06.026

Hakamata T, Hirata T, Muraoka K (1992) Evaluation of land use and river water quality of the Tsukuba Mountains ecosystem. Japan Catena 19(5):427–439. https://doi.org/10.1016/0341-8162(92)90042-A

Hezarjaribi A, Sourell H (2007) Feasibility study of monitoring the total available water content using non-invasive electromagnetic induction-based and electrode-based soil electrical conductivity measurements. Irrig Drain 56(1):53–65. https://doi.org/10.1002/ird.289

Hübner R, Heller K, Günther T, Kleber A (2015) Monitoring hillslope moisture dynamics with surface ERT for enhancing spatial significance of hydrometric point measurements. Hydrol Earth Syst Sci 19(1):225–240. https://doi.org/10.5194/hess-19-225-2015

Jones JAA (1987) The effects of soil piping on contributing areas and erosion patterns. Earth Surf Process Landforms 12(3):229–248. https://doi.org/10.1002/esp.3290120303

Kim HK, Jang TI, Im SJ, Park SW (2009) Estimation of irrigation return flow from paddy fields considering the soil moisture. Agric Water Manag 96(5):875–882. https://doi.org/10.1016/j.agwat.2008.11.009

Liu C-W, Chen S-K, Jang C-S (2004a) Modelling water infiltration in cracked paddy field soil. Hydrol Process 18(13):2503–2513. https://doi.org/10.1002/hyp.1478

Liu C-W, Huang H-C, Chen S-K, Kuo Y-M (2004b) Subsurface return flow and ground water recharge of terrace fields in northern Taiwan1. JAWRA J Am Water Resour Associat 40(3):603–614. https://doi.org/10.1111/j.1752-1688.2004.tb04446.x

Michot D, Benderitter Y, Dorigny A, Nicoullaud B, King D, Tabbagh A (2003) Spatial and temporal monitoring of soil water content with an irrigated corn crop cover using electrical resistivity tomography. Water Resour Res 39:1138. https://doi.org/10.1029/2002WR001581

Montgomery DR, Dietrich WE, Torres R, Anderson SP, Heffner JT, Loague K (1997) Hydrologic response of a steep, unchanneled valley to natural and applied rainfall. Water Resour Res 33(1):91–109. https://doi.org/10.1029/96WR02985

Mori Y, Sasaki M, Morioka E, Tsujimoto K (2019) When do rice terraces become rice terraces? Paddy Water Environ, 17(3):323–330. https://doi.org/10.1007/s10333-019-00727-0

Nakagiri T, Kato H, Maruyama S, Hashimoto S, Horino H, Sakurai S (2019) Possibility of quantitative assessment of the contribution of paddy irrigation and caldera lakes to river water in Bali Island using water isotopic physics. Paddy Water Environ 17(3):463–473. https://doi.org/10.1007/s10333-019-00742-1

Onishi T, Horino H, Nakamura K, Mitsuno T (2003) Evaluation of groundwater properties in terraced paddy fields using transient unsaturated-saturated water flow analysis. Trans Jpn Soc Irrig Drain Reclam Eng (japan) 227:97–104. https://doi.org/10.11408/jsidre1965.2003.657

Parr JF, Bertrand AR (1960) Water infiltration into soils. In: Normax AG (ed) Advances in agronomy, vol 12. Academic Press, Amsterdam, pp 311–363. https://doi.org/10.1016/S0065-2113(08)60086-3

Chapter Google Scholar

Samouëlian A, Cousin I, Tabbagh A, Bruand A, Richard G (2005) Electrical resistivity survey in soil science: a review. Soil Tillage Res 83(2):173–193. https://doi.org/10.1016/j.still.2004.10.004

Sikandar P, Christen EW (2012) Geoelectrical sounding for the estimation of hydraulic conductivity of alluvial aquifers. Water Resour Manag 26(5):1201–1215. https://doi.org/10.1007/s11269-011-9954-3

Song JH, Ryu JH, Park J, Jun SM, Song I, Jang J et al (2016) Paddy field modelling system for water quality management. Irrig Drain 65:131–142. https://doi.org/10.1002/ird.2034

Tiab D, Donaldson EC (2012) Chapter 3—Porosity and Permeability. In: Tiab D, Donaldson EC (eds) Petrophysics, 3rd edn. Gulf Professional Publishing, Boston, pp 85–219. https://doi.org/10.1016/B978-0-12-383848-3.00003-7

Tromp-van Meerveld H, McDonnell J (2006) Threshold relations in subsurface stormflow: 2. The fill and spill hypothesis. Water Resour Res 42(2):W02411. https://doi.org/10.1029/2004WR003800

Tsai W-N (2021) Relationships between variations in electrical resistivity and precipitation and their implications for landslides: case study in the lantai area, Ilan Taiping Mountain, Northeast Taiwan. Master’s dissertation, National Central University, Taiwan. Retrieved from https://hdl.handle.net/11296/d9299t

Tulip SS, Siddik MS, Islam MN, Rahman A, Torabi Haghighi A, Mustafa SMT (2022) The impact of irrigation return flow on seasonal groundwater recharge in northwestern Bangladesh. Agric Water Manag 266:107593. https://doi.org/10.1016/j.agwat.2022.107593

Uchida T, Tromp-van Meerveld I, McDonnell JJ (2005) The role of lateral pipe flow in hillslope runoff response: an intercomparison of non-linear hillslope response. J Hydrol 311(1):117–133. https://doi.org/10.1016/j.jhydrol.2005.01.012

Vanella D, Cassiani G, Busato L, Boaga J, Barbagallo S, Binley A, Consoli S (2018) Use of small scale electrical resistivity tomography to identify soil-root interactions during deficit irrigation. J Hydrol 556:310–324. https://doi.org/10.1016/j.jhydrol.2017.11.025

Vereecken H, Huisman JA, Bogena H, Vanderborght J, Vrugt JA, Hopmans JW (2008) On the value of soil moisture measurements in vadose zone hydrology: a review. Water Resour Res 44(4):W00D06. https://doi.org/10.1029/2008WR006829

Wu L, Pan L, Mitchell J, Sanden B (1999a) Measuring saturated hydraulic conductivity using a generalized solution for single-ring infiltrometers. Soil Sci Soc Am J 63(4):788–792. https://doi.org/10.2136/sssaj1999.634788x

Wu R-S, Lin K-M, Lee J-F (1999b) Study on returen flow in the rice paddy field. J Chinese Agric Eng 45(1):72–82

Download references

Acknowledgements

This research was funded by the Chi-Seng Water Research and Development Foundation, Taipei, and Ministry of Education, Republic of China (Taiwan) under Grant 112L893501

Author information

Authors and affiliations.

Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei City, Taiwan

Qun-Zhan Huang, Shao-Yiu Hsu & Jie Hu

Hsing Wu University, New Taipei City, Taiwan

Yu-Chuan Chang

You can also search for this author in PubMed Google Scholar

Contributions

All authors contributed to the study conception and design. Methodology, validation, formal analysis, investigation, and data curation were performed by Qun-Zhan Huang and Jie Hu. Resources, writing–original draft preparation, and visualization were provided by Qun-Zhan Huang. Writing–review and editing, supervision, and project administration were performed by Shao-Yiu Hsu. Funding acquisition and resources were performed by Yu-Chuan Chang and Shao-Yiu Hsu. All authors read and approved the final manuscript.

Corresponding author

Correspondence to Shao-Yiu Hsu .

Ethics declarations

Competing interests.

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Huang, QZ., Hsu, SY., Hu, J. et al. Observations of electrical resistivity tomography and groundwater level under an irrigated terraced paddy field in northern Taiwan. Paddy Water Environ (2024). https://doi.org/10.1007/s10333-024-00979-5

Download citation

Received : 11 December 2023

Revised : 30 April 2024

Accepted : 29 May 2024

Published : 13 June 2024

DOI : https://doi.org/10.1007/s10333-024-00979-5

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

Electrical resistivity tomography
Terraced paddy field
Subsurface return flow
Infiltration
Find a journal
Publish with us
Track your research

IMAGES

Experiment to determine the resistivity of a metal wire
Lab 101 Experiment 9 Resistivity Measurements
Resistivity of a Wire || Experiments || FlashyScience
Lab Report Explained: Length and Electrical Resistance of a Wire
Electrical Resistivity
Relation between resistance and resistivity through a simple experiment

VIDEO

Electrical Experiment: What Happens When Phase and Neutral Meet? THIS VIDEO IS FICTIONAL
What is electrical resistivity of a material? What is its unit? Describe an experiment to
SIT PHYSICS LAB ... RESISTIVITY EXPERIMENT 27/12/23 #comedk #phy #experiment #siddganga
Electrical Resistivity experiment
Collin's Lab
Physics Lab 2 [Experiment 2

COMMENTS

Required Practical: Investigating Resistivity
The aim of the experiment is to determine the resistivity of a 2 metre constantan wire; Variables: ... Make sure there are no liquids close to the equipment, as this could damage the electrical equipment; Worked example. A student wants to find the resistivity of a constantan wire. They set up the experiment by attaching one end of the wire to ...
Core Practical 2: Investigating Resistivity
Keep liquids away from electrical equipment; Worked example. A student conducts an experiment to find the resistivity of a constantan wire. They attach one end of the wire to a circuit that contains a 6.0 V battery. The other end of the wire is attached by a flying lead to the wire at different lengths.
PDF General Physics II Lab (PHYS-2021) Experiment ELEC-4: Resistivity
ELEC-4: Resistivity Page 1 of 6 . Written by Chuck Hunt, PASCO; Modified by Donald Luttermoser, ETSU. General Physics II Lab (PHYS-2021) Experiment ELEC-4: Resistivity . 1 Equipment. Included: 1 Resistance Apparatus EM-8812 1 Voltage Sensor UI-5100 1 Patch cords (set of 5) SE-9750 1 850 Universal Interface UI-5000 1 PASCO Capstone
9.4: Resistivity and Resistance
The resistivity of a material is a measure of how strongly a material opposes the flow of electrical current. The symbol for resistivity is the lowercase Greek letter rho, ρ, and resistivity is the reciprocal of electrical conductivity: ρ = 1 σ. The unit of resistivity in SI units is the ohm-meter (Ω ⋅ m.
PDF E5a: Resistivity
Electrical resistivity is an intrinsic property of a material and measure how strong it opposes the flow of electrical current. A lower value of resistivity indicates that the material ... This experiment is divided into three parts. In the first part, a single wire and Ohm's Law will be used to find the resistivity of brass. In the second ...
Resistance in a Wire
We recommend using the latest version of Chrome, Firefox, Safari, or Edge. Observe changes to the equation and wire as you play with the resistivity, length, and area sliders.
The Electrical Properties of Materials: Resistivity
This lab has two parts: a scripted study of the resistivity of tungsten (Section 4.1, and a more free-form determination of the resistivity of various materials. In the latter section, we do not give you detailed instructions: you are responsible for both designing and executing the experiment, and analyzing and presenting your results. 4.1
Electrical resistance
Student experiment: Measurement of resistivity. Complete this section by asking your students to measure the resistivity of several metal wires. This experiment provides an opportunity for a detailed discussion of the treatment of experimental errors. Episode 112-3: Measuring electrical resistivity (Word, 30 KB) Student questions: Using these ideas
PDF Online Lab: Resistivity
Resistivity(ˆ)isafundamentalmaterialproperty,whiletheresistance(R)ofanelectricalcon- ducting wire depends on several factors, such as: type of conductor material, length of the conductor, cross-sectional area, and the temperature of the wire.
PDF Experiment 24 THE TEMPERATURE DEPENDENCE OF RESISTANCE
DC electrical conductivity. 3. Given our earlier calculation of . n = ×0.85 10 cm. 23 3. in copper and its measured room-temperature resistivity of ρσ= ≈1 1.6 micro-ohm centimeters, copper's corresponding relaxation time would be ≈×3 10 sec. −14. For comparison, this time equals the
Electrical Resistivity Experiments for Lesson Plans & Science Fair Projects
Electrical resistivity (also known as specific electrical resistance) is a measure of how strongly a material opposes the flow of electric current. A low resistivity indicates a material that readily allows the movement of electrical charge. The SI unit of electrical resistivity is the ohm metre. The electrical resistivity ρ ( rho) of a ...
Core Practical 7: Investigating Resistivity
This could damage the electrical equipment; Or cause a short circuit which will affect the results; Worked example. A student conducts an experiment to find the resistivity of a constantan wire. They attach one end of the wire to a circuit that contains a 6.0 V battery. The other end of the wire is attached by a flying lead to the wire at ...
Resistivity of a Wire || Experiments || FlashyScience
The electrical resistivity of a wire tells us how well the wire material conducts electricity. This is crucial information for any application that involves conducting electricity, including wind turbines, electric vehicles, household electrical goods and computers. Here you can measure the resistivity of wires of different materials and widths ...
PDF Electrical Resistivity and Hall Effect (Part I) Overview
In the first part of this experiment you will 1) attach leads to a Co/Cu multilayer thin film, 2) measure its electrical resistivity, and 3) measure the giant magnetoresistance effect in an external magnetic field. The rest of this document will guide you through the background and experiments to perform.
PDF Lab Sim 08: Resistance and Resistivity of Graphite
Resistivity is the tendency of a material to behave as a resistor. You already know that not everything conducts electricity equally well and that some materials (like copper) resist very little, while others (like rubber) provide enough resistance to effectively prevent the flow of current. Resistivity ( ) is a fundamental material property (like
Lab Report Explained: Length and Electrical Resistance of a Wire
In conclusion, the experiment was a successful investigation that successfully answers the research question of how basically changing the length of a wire (especially a nichrome wire with a diameter of 0.315 cut into measurements of 10cm, 20cm, 30cm, 40cm and 50cm) could affect the electrical resistance generated within the wires.
Resistivity of a Wire || Experiments || FlashyScience
The electrical resistivity of a wire tells us how well the wire material conducts electricity. This is crucial information for any application that involves conducting electricity, including wind turbines, electric vehicles, household electrical goods and computers. Here you can measure the resistivity of wires of different materials and widths ...
Experiments with Resistivity
My experimental evidence (Preliminary Results) as shown in A8d suggested a final value of around 1.06 x10 ^6 m (as Below) Length of wire = 0.100 m Resistance 1 = 2.13 Resistance 2 = 2.09. Resistance = Resistivity x Length the Wire Cross Section Area of Wire. Average Resistance = 2.11 Wire Thickness = 0.270 mm.
LAB Report 5
Resistivity is commonly represented by the Greek letter ρ (rho). The SI unit of electrical resistivity is the ohm-meter (Ω⋅m). The main objective of this lab is to examine the resistivity of a piece of graphite from a pencil. We will explore how resistivity varies with length and area of a material. Using the gathered data, we will plot
Lab 3 Resistivity
lab report resistivity course: phy156 section: 12919 student name: gamoi paisley lab partner: asaba anis date: objective: to determine the resistivity of. Skip to document. ... Part 2 of this experiment used the slope of R vs. L and the area of the wire to determine the wires resistivity 1×10 -6 Ωּm. Both methods produced similar results and ...
Electrical Resistivity
Theory. Electrical resistivity methods measure the ability of electrical current to flow through the subsurface. Thus, resistivity methods require electrical connection (i.e., galvanic coupling) with the ground, and this is achieved with the use of metal electrodes. Typically, a battery-run power supply is used to apply a direct current (DC ...
(PDF) Electrical Resistivity Measurements: a Review
for the resistivity mea surement of solid kind o f samples. 1. Introduction. Electrical resistivity is one of the most sensitive indicators of changes in the nature of the. chemical b inding. I n ...
Electrical Resistivity Behavior of Saline Soil under Low-Temperature
Researchers found that electrical resistivity methods outperform traditional ground surveying methods in frozen soils for their greater convenience and cost-effectiveness. ... a series of laboratory experiments using the Wenner method were conducted to determine the relationship between soil electrical resistivity and soil geotechnical ...
24 Fun Electricity Experiments and Activities for Kids
Get tutorial: Salt and pepper experiment. Create Play Travel. 4. Move a bubble using a balloon. Balloons are a fun way to teach about static electricity. Combine them with bubbles for a hands-on activity students will really love. Get tutorial: Bubble experiment. I Heart Crafty Things. 5.
Observations of electrical resistivity tomography and ...
The electrical resistivity is sensitive to the water content (Samouëlian et al. 2005; Chen et al. 2019); ... The infiltration experiment with sandboxes in Gouet-Kaplan et al. demonstrated similar phenomena, where initially, the ratio of old water accounting for the washout water is high, gradually reducing to a stable level. The latter stage ...

	\(\sigma\) \((\Omega \cdot m)^{-1}\)	\(\rho\) \((\Omega \cdot m)\)	\(\alpha\) \((^oC)^{-1}\)

Silver	\(6.29 \times 10^7\)	\(1.59 \times 10^{-8}\)	0.0038
Copper	\(5.95 \times 10^7\)	\(1.68 \times 10^{-8}\)	0.0039
Gold	\(4.10 \times 10^7\)	\(2.44 \times 10^{-8}\)	0.0034
Aluminum	\(3.77 \times 10^7\)	\(2.65 \times 10^{-8}\)	0.0039
Tungsten	\(1.79 \times 10^7\)	\(5.60 \times 10^{-8}\)	0.0045
Iron	\(1.03 \times 10^7\)	\(9.71 \times 10^{-8}\)	0.0065
Platinum	\(0.94 \times 10^7\)	\(10.60 \times 10^{-8}\)	0.0039
Steel	\(0.50 \times 10^7\)	\(20.00 \times 10^{-8}\)
Lead	\(0.45 \times 10^7\)	\(22.00 \times 10^{-8}\)
Manganin (Cu, Mn. Ni alloy)	\(0.21 \times 10^7\)	\(48.20 \times 10^{-8}\)	0.000002
Constantan (Cu, Ni alloy)	\(0.20 \times 10^7\)	\(49.00 \times 10^{-8}\)	0.00003
Mercury	\(0.10 \times 10^7\)	\(98.00 \times 10^{-8}\)	0.0009
Nichrome (Ni, Fe, Cr alloy)	\(0.10 \times 10^7\)	\(100.00 \times 10^{-8}\)	0.0004

Carbon (pure)	\(2.86 \times 10^{4}\)	\(3.50 \times 10^{-5}\)	-0.0005
Carbon	\((2.86 - 1.67) \times 10^{-6}\)	\((3.5 - 60) \times 10^{-5}\)	-0.0005
Germanium (pure)		\(600 \times 10^{-3}\)	-0.048
Germanium		\((1 - 600) \times 10^{-3}\)	-0.050
Silicon (pure)		2300	-0.075
Silicon		0.1 - 2300	-0.07

Amber	\(2.00 \times 10^{-15}\)	\(5 \times 10^{14}\)
Glass	\(10^{-9} - 19^{-14}\)	\(10^9 - 10^{14}\)
Lucite	\(< 10^{-13}\)	\(> 10^{13}\)
Mica	\(10^{-11} - 10^{-15}\)	\(10^{11} - 10^{15}\)
Quartz (fused)	\(1.33 \times 10^{-18}\)	\(75 \times 10^{16}\)
Rubber (hard)	\(10^{-13} - 10^{-16}\)	\(10^{13} - 10^{16}\)
Sulfur	\(10^{-15}\)	\(10^{15}\)
Teflon	\(< 10^{-13}\)	\(> 10^{13}\)
Wood	\(10^{-8} - 10^{-11}\)	\(10^8 - 10^{11}\)

Margin Size

9.4: Resistivity and Resistance

Learning Objectives

Resistivity

Example \(\PageIndex{1}\): Current Density, Resistance, and Electrical field for a Current-Carrying Wire

Exercise \(\PageIndex{1}\)

Temperature Dependence of Resistivity

Definition: Resistance

Material and shape dependence of resistance

Example \(\PageIndex{2}\): Calculating Resistance

Exercise \(\PageIndex{2}\)

The Resistance of Coaxial Cable

Exercise \(\PageIndex{3}\)

Phet: Battery-Resistor Circuit

Share this article:

Preparation for resistance topic

Main aims of this topic

Prior knowledge

Where this leads

Demonstration: The meaning of resistance

Discussion: Defining resistance

Worked examples: Calculating resistance

Student questions: Simple calculations

Student experiment: Characteristics of metal wire

Discussion: Ohm’s law

Download this episode

Student experiment: Further characteristics

Student experiment – alternative version

Discussion: The results

Student questions: On characteristics

Resistance and temperature

Discussion and demonstrations: Resistance and temperature

Discussion: Free-electrons in metals

Student experiment: Thermistor behaviour

Discussion and demonstrations: Conduction in semiconductors

Discussion: Superconductivity

How low can we go?

Student questions: Using these ideas

Semiconductor devices

Student experiment: Characteristics of an LDR

Demonstration: Semiconductor devices in use

Resistivity

Discussion: Variation of resistance with length and area

Student experiment: Variation of resistance with length and area

Student experiment: Measurement of resistivity

Support our manifesto for change

Physics Links Explorer

Temperature dependence

Complex resistivity

Resistivity density products

Core Practical 7: Investigating Resistivity ( Edexcel International A Level Physics )

Core Practical 7: Investigating Resistivity

Equipment List

Analysis of Results

Evaluating the Experiment

Safety Considerations

Worked example

You've read 0 of your 0 free revision notes

Join the 100,000 + Students that ❤️ Save My Exams

Author: Joanna

Lab Report Explained: Length and Electrical Resistance of a Wire

INTRODUCTION AND BACKGROUND THEORY

RESEARCH QUESTION

MATERIAL AND APPARATUS

EXPERIMENT DESIGN SETUP WITH CLEAR LABELS

EXPERIMENT METHOD/PROCEDURE

CONCLUSION & EVALUATION

EVALUATION AND SUGGESTIONS

Related Posts

Leave a Reply Cancel reply

Tensile Testing (lite)

Ohm's Law

Free-fall due to Gravity

Radioactivity

Resistivity of a Wire

Hooke's Law

Specific Heat Capacity: Solids

Acceleration and Force

Density of Solids & Liquids

Thermal Insulation