science experiment for light

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3 Super Simple Light Experiments for Kids to Do

Literacy & ABCs Science Toddlers Grade School Kindergartners Preschoolers Experiment Paper Plates 18 Comments

Science experiments are always a big hit in my house and this light experiment for kids will brighten everyone’s day – literally!

3 Super Simple Light Experiments for Kids

What three things can light do? This is the guiding question for this simple and fun light experiment for kids.

To Set up Your Own Simple Light Science Experiment, You’ll Need:

• Magnifying glass
• Paper plate or anything opaque
• Piece of paper

Try our favorite 50 simple science experiments .

Talking About Science Basics with Kids

Science activities are always a great time to practice using fun science terms. This simple light science experiment introduces three new ones:

• penetrate: or when light will pass through an object to be visible on the other side
• reflect: or when the light bounces back at you, like with a mirror or something shiny
• stop: or when the light is blocked, not reflecting or penetrating
• variable: what changes in different steps on the experiment

It can help if you write down these words and their meanings on a piece of paper or flashcards.

You could use actual words or draw a picture.

For older kids, you could also dive a little bit deeper. I love this quick explanation about the properties of light from Ducksters .

Before Your Light Experiments for Kids

This simple science experiment includes an opportunity for making predictions and recording observations.

Predicting is just making a guess based on what you already know.

You could get started by asking your kids: “What do you know about light?”

Create a quick and simple legend for the light experiment.

Write down your children’s predictions and make a quick chart. One column is for the prediction and the other is for the observation, plus some rows for the variables.

Label the rows with the names of your three objects, or variables (what’s changing each time). Hint: mirror, magnifying glass, plate, etc.

At the top of one column write: “What will the light do?” . (Prediction)

And then above the other column, write: “What does the light do?” . (Observations)

As you experiment, you’ll also jot down what happens with the light, or what you observe. Observe and observation in science is just a fancy way to explain telling what you saw happening during the experiment.

Ask these helpful questions as you predict what happens:

• Will the light penetrate the paper plate or will it stop?
• Will the light reflect off of the magnifying glass or penetrate?
• And will the mirror stop the light?

Take time to look at each object, discuss the three terms associated with light (penetrate, reflect, stop).

Make predictions, or guesses, about what the light will do with each object.

Write your predictions in the first column of the chart.

Now Experiment with Light Together

Once your predictions are made and the properties of light have been discussed, it’s time to do the experiment.

Choose the first object and have your kids shine the flashlight at the object.

Watch how the light reacts with the object. Does it shine through, shine back at you, or stop completely?

Record on your observation chart what the light did with that object. Check to see if your predictions were correct.

Keep going with the rest of the objects, making sure to observe and record your findings.

Our Easy Light Experiments for Kids

We chose the mirror first. My son held the mirror and my daughter used the flashlight.

I encouraged them to explain what they noticed about the light. Both recognized that the light was shining back at us, or reflecting.

We talked for a minute about using “refect” to describe what the light was doing.

Keep shining with a simple indoor reflection activity !

My daughter wrote “reflect” in our observation column on our chart. I helped her with the spelling, but only a little.

The Paper Plate

Our second variable for the light experiment was the paper plate. This time my kids switched roles with my daughter holding the plate and my son shining the flashlight at the object.

My kids quickly noticed that the light didn’t go anywhere except for on the plate.

We discussed together how this showed that the light stopped because the plate blocks or stops the light. I also added in the word “opaque,” which means that light does not pass through.

My son recorded “stop” for the plate.

You can also introduce the word “absorb” to your kids at this point in the experiment, as that is another term for stopping the light.

Originally, the kids had thought that the plate might reflect the light. Our prediction was incorrect and we talked about that for a minute or so.

Learn more about opaque objects with a fun shadow play activity !

The Magnifying Glass

Our final object was the magnifying glass. It was my turn to shine the light as both my kids held the object.

This time the light went through the magnifying glass, shining onto the floor below. I shared the term “transparent,” meaning that light passes completely through, as we talked about this part of the experiment.

I recorded our findings on the chart. We reviewed each object and outcome together while comparing our observations to our predictions.

Keep Playing with Light!

Even though we had finished the “formal” experiment, my kids kept the learning going! They ran through the house, shining the flashlight on all sorts of objects and saying whether the light reflected, stopped, or penetrated.

I love how much ownership they took of their learning!

We love playing with a fun flashlight scavenger hunt for kids !

This fun extension activity went on for quite a while. And it’s something that I know I can keep returning to again and again, adding more challenging terminology as they grow.

What are some other fun science experiments for kids you have done? We’d love to check-out your creative learning ideas!

About alisha warth.

I have raised my children doing activities with them. As a homeschool mom, I am always looking for ways to make our learning fun. I'm honored to be able to contribute my ideas to the awesome site that is Hands On As We Grow.

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18 comments.

Stacey A Johnson says

November 24, 2020 at 8:46 pm

This is fantastic! Thank you for sharing! I have been putting science bags together to send home for my kinders because we are doing online school….I was looking for some light activities because we are going to tie them into the holidays we study in December. (The idea that most celebrations, customs, rituals, use some sort of light) I can’t wait to do this with them!

MaleSensePro says

February 10, 2020 at 11:29 pm

Its a great learning experience.. its indeed the best kind of way kids should learn, thanks for sharing :)

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Ignite Your Kids’ Curiosity with These 16 Dazzling Light Experiments

Activities » Science » Ignite Your Kids’ Curiosity with These 16 Dazzling Light Experiments

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From rainbow light refractions to exploring the visible spectrum, there are so many fascinating and fun science projects about light for children to explore.

Whether you’re a teacher in need of activities that will engage your students or a homeschooler who wants to find new methods of educating your little ones, this ultimate list of light experiments for kids is sure to keep them happily learning!

With easy-to-follow instructions and simple materials, these exciting experiments dive into basic concepts such as reflection, absorption, diffusion, and much more.

I scoured the internet to discover the BEST activities for experimenting with light. This post includes dozens of fun science light experiments for kids to keep you and your kids busy. These science lessons are so good that kids have fun, are engaged, and want to learn more!

Light Science Experiments for Kids

Build your diy spectroscope from buggy & buddy.

Kids will LOVE to make their DIY spectroscope! The best part of this science activity is that it can be done with a few simple materials and explore the spectrum of different light sources.

The author offers a step-by-step, easy-to-follow approach, which is always helpful! 

This light science activity for kids makes a great addition to a unit on light or weather. You get to see rainbows, so add it to an April preschool unit or St. Patrick’s Day-themed unit.

Sky Science – Why does the sky change colors? from Steam Powered Family

Finally, have an answer to the age-old question:  why is the sky blue? Even better, explore why the sky changes color at sunrise and sunset.

You can explain until you’re blue in the face about the science of the sky colors, but experimenting brings the understanding to a new level. 

Learning about Optics with Two Fun Light Experiments! by From Engineer to Stay at Home Mom

Explore how light behaves with this activity! Furthermore, explain the concept of OPTICS as the study of how light works. This water and light experiment showed him how light works.   

Explore the Eye’s Blind Spot from Carrots Are Orange

The blind spot is a little spot of the eye. Everyone has a blind spot. The blind spot is the point in the eye where all the nerves in the eye come together.

The nerves form a bundle called the optic nerve, which runs from the eye to the brain.

So, why makes the blind spot “blind’?

Simple Light Refraction Experiment from Look We’re Learning

This simple light refraction experiment teaches kids an easy way to teach kids about light!

Light Activities for Preschoolers from Carrots Are Orange

This post includes loads of light energy experiments and ideas to explore.

DIY Sundial from KC Adventures

Learn an easy way to make a sundial using simple materials.

UV Light Experiment from Inspiration Laboratories

Try this simple exploration to explore ultraviolet light with your child.

Exploring Science Through Art: Colour & Light by Childhood 101

This activity is sweet and to the point—what a lovely hands-on way to explore color and light.

Reflection Science with Light Patterns in a Box from Buggy & Buddy

A super cool and remarkably easy-to-put-together light energy experiment.

Rainbow Science for Kids: Exploring Prisms from Buggy & Buddy

Prisms are one of the most beautiful and simple materials. Learn ways to explore light reflection with this simple object!

Easy Motion Science Experiment from Carrots Are Orange

Learn how movies are made with this  easy motion science experiment . My sons have been on a “how does this work?” kick. This easy science experiment  was one answer to “how do movies get onto a screen?”

Science for Kids: How to Make a Kaleidoscope

Kids love light reflection experiments! Learn  how to make a kaleidoscope in this fun & easy science activity and a craft for kids. Kids love to explore light, reflections, and symmetry by creating their kaleidoscope.

Build a Light Maze

This science experiment on light is unique and embraces imagination (and a flashlight experiment which is always fun!). My son LOVED this “build a light maze activity,” and I bet your child will enjoy it, too.

Candy Wrapper Science – Color Mixing

Kids will have a lot of fun exploring color mixing and light with this hands-on science exploration.

Laser Science for Kids: The Glowing Lollipop

Learn about light refraction with this cool laser pointer lollipop experiment.

As you can see, there are a ton of great light experiments for kids that are both fun and educational. We hope this list has inspired you to try out some of these activities with your children or students.

If you end up trying one (or more) of them, we’d love to hear about it. Which activity jumped out at you? Share it with your friends!

Other Science Activities:

How to Build a Magnetic Car with Your Kids

DIY Magnetic Sand Table

Magnetism Science Experiments for Kids: Magnetic Board

Light Activities for Preschoolers - Learning about Light Energy

Science Activity with Milk & Food Coloring

Science of Flight Activities for Kids

Easy Science Activity with Balloons - How to Build a Balloon Rocket

Easy Science Experiments for Kids - Surface Tension

Easy Motion Science Experiment that Will Wow Your Kids

10+ Amazing Science Activities for Preschoolers

Arctic Animal Science Experiment for Preschoolers

Super Cool Easy Science Experiments for Kids - Learn about Sound

Preschool Physical Science Activity - Leaf Pounding

The Coolest Preschool Science Activity - Surface Tension

What Do Germs Look Like - Science Activity for Kids

Explore How Cats Eyes Glow with this Science Activity

How to Make a Pulley with Kids - Easy Science Activity

Electricity Experiments with Kids: Super Easy Science Experiments

[Baking Soda and Vinegar] Experiment with Balloons - Earth Day Science

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Top 15 Light Related Science Experiments

Light experiments lets us unlock some of nature’s most intriguing riddles and appreciate the magic that illuminates our everyday experiences.

We have carefully selected the best light-related experiments, prioritizing fun and educational experiences that will surely engage young minds.

Our compilation of light experiments will illuminate the minds of students and teachers alike. This curated collection offers an extraordinary opportunity to explore the captivating world of light through hands-on activities.

1. Potato Light Bulb

Prepare to be amazed by the power of potatoes in our extraordinary potato light bulb experiments! In these captivating experiments, students will discover the remarkable ability of a humble potato to generate electricity and light up an LED bulb.

Learn more: Potato Light Bulb

2. Bending Light

In these mesmerizing light experiments, students have the opportunity to unravel the mysteries of refraction and explore the wonders of bending light.

3. Light Refraction

By engaging in these experiments, students will not only witness the mesmerizing effects of light refraction but also gain a deeper understanding of the scientific principles behind it.

4. Newton’s Light Spectrum Experiment

Step into the fascinating world of light and color with Newton’s Light Spectrum Experiment! Inspired by the groundbreaking discoveries of Sir Isaac Newton, these captivating experiments will take students on a journey to explore the nature of light.

5. Newton’s Prism Experiment

Learn about optics and unravel the mysteries of light with Newton’s Prism Experiment. Inspired by Sir Isaac Newton’s groundbreaking discoveries, these experiments offer a thrilling opportunity for students to explore the phenomenon of light dispersion and the creation of a vivid spectrum of colors.

6. Total Internal Reflection

These experiments provide a hands-on opportunity for students to observe and investigate how total internal reflection can be harnessed in practical applications such as fiber optics and reflective surfaces.

7. Colored Light Experiments

Prepare to immerse yourself in a vibrant world of colors with these captivating colored light experiments! In these hands-on activities, students will uncover the magic of colored light and its intriguing properties.

8. Capture a Light Wave

By employing innovative techniques and tools, students will learn how to capture and analyze light waves, unraveling the secrets hidden within their intricate patterns.

9. Home-made Kaleidescope

Unleash your creativity and embark on a mesmerizing journey of light and patterns with our homemade kaleidoscope experiments! By constructing your very own kaleidoscope, you’ll unlock optical wonders.

Learn more: Home-made Kaleidescope

10. Push Things with Light

Through engaging hands-on activities, students will experiment with the fascinating principles of photon momentum and the transfer of energy through light.

11. Erase Light with a Laser: The Photon Experiment

Can light be erased? Through hands-on activities, students will discover surprising answers. By utilizing lasers, students will learn about the principles of photon absorption and emission, investigating whether it is possible to erase light.

12. Exploring Shapes and Patterns on a Mirror Box

By creating your own mirror box, you’ll learn about optical illusions and reflections. In these experiments, students will explore the fascinating interplay between light, mirrors, and geometry.

Learn more: Exploring Shapes and Patterns on a Mirror Box

13. Electromagnetic Spectrum Experiment

Get ready for an illuminating adventure as we dive into the fascinating world of visible light where students will have the opportunity to explore the electromagnetic spectrum and unravel the mysteries of light.

 14. Light Patterns in a Box

By manipulating light sources and objects, students will witness the magic of shadows, diffraction, and interference, resulting in a dazzling display of intricate patterns and colors.

Learn more: Light Patterns in a Box

15. Light Maze

Prepare to navigate a mesmerizing journey through the enchanting world of light with our captivating light maze experiments! In these immersive activities, students will learn about the magic of manipulating light to create intricate mazes and pathways.

Similar Posts:

• 68 Best Chemistry Experiments: Learn About Chemical Reactions
• Top 100 Fine Motor Skills Activities for Toddlers and Preschoolers
• Top 40 Fun LEGO Science Experiments

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Light Refraction Experiment

March 30, 2020 By Emma Vanstone Leave a Comment

This light refraction experiment might be one of the most simple to set up science experiments we’ve ever tried. It is a bit tricky to explain, but impressive even if you can’t quite get your head around it!

If you like this activity don’t forget to check out out our other easy science experiments for kids .

Materials for Light Refraction Experiment

Paper or card

Instructions

Fill the glass almost to the top.

Draw arrows on one piece of of card or paper. Place the paper behind the glass and watch as the arrow points the other way.

Now try to think of a word that still makes sense if you put it behind the glass.

We tried bud , the green ( badly drawn ) plant is on the opposite side when the paper is not behind the glass.

NOW works well too 🙂

How does this work?

Refraction ( bending of light ) happens when light travels between two mediums. In the refraction experiment above light travels from the arrow through the air, through the glass, the water, the glass again and air again before reaching your eyes.

The light reaching your eye (or in this case our camera) coming from the arrow is refracted through the glass of water. In fact the glass of water acts like a convex lens (like you might have in a magnifying glass). Convex lenses bend light to a focal point . This is the point at which the light from an object crosses.

The light that was at the tip of the arrow is now on the right side and the light on the right side is now on the left as far as your eye is concerned (assuming you are further away from the glass than the focal point.

If you move the arrow image closer to the glass than the focal point it will be the way around you expect it to be!

More Refraction experiments

Create an Alice in Wonderland themed version of this too!

Find out how to make your own magnifying glass .

We’ve also got a fun disappearing coin trick .

Or try our light maze to learn about reflection .

Last Updated on February 22, 2021 by Emma Vanstone

Safety Notice

Science Sparks ( Wild Sparks Enterprises Ltd ) are not liable for the actions of activity of any person who uses the information in this resource or in any of the suggested further resources. Science Sparks assume no liability with regard to injuries or damage to property that may occur as a result of using the information and carrying out the practical activities contained in this resource or in any of the suggested further resources.

These activities are designed to be carried out by children working with a parent, guardian or other appropriate adult. The adult involved is fully responsible for ensuring that the activities are carried out safely.

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Diffraction

Light bends when it passes around an edge or through a slit. This bending is called diffraction. You can easily demonstrate diffraction using a candle or a small bright flashlight bulb and a slit made with two pencils. The diffraction pattern—the pattern of dark and light created when light bends around an edge or edges—shows that light has wavelike properties.

• Two clean new pencils with erasers
• A piece of transparent tape (any thin tape will do)
• A Mini Maglite flashlight ( do not substitute other flashlights ) or a candle with matches or a lighter
• Optional: Pieces of cloth, a feather, plastic diffraction grating, metal screen, a human hair

Related Exhibits

Science Fun

Light And Sound Science Experiments

Easy light and sound science experiments you can do at home! Click on the experiment image or the view experiment link below for each experiment on this page to see the materials needed and procedure. Have fun trying these experiments at home or use them for SCIENCE FAIR PROJECT IDEAS.

Clucking Chicken In A Cup:

Talking String:

Teach A String To Talk

Trombone Straw:

Noisy Paper:

Bug On A Leash:

Super Easy Pan Flute:

Make Music With This Easy Sound Experiment

Duck In A Cup:

Crazy Kazoo:

• 3 index cards
• small piece of modeling clay or sticky tack
• hole puncher
• science journal
• For each index card, use a ruler to draw lines connecting opposite corners of the card.
• At the intersection of the two lines, use a hole puncher to punch a hole in the center of the index cards.
• For each card, use a small piece of modeling clay and place the card into the clay to create a "stand" for the card. Place the cards so that they stand vertically and at an equal distance from each other. See Diagram.
• Place the flashlight at one end of the row of index cards and turn off the light in the room.
• Arrange the index cards so that light can be seen through all the holes.
• Observe and record your observations.
• How can light be seen through all the index cards?
• What does the experiment prove about the path light travels?
• What would happen if the holes were smaller?

Back to Kids Science Projects Page

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Back to Kids Study Page

Buggy and Buddy

Meaningful Activities for Learning & Creating

January 26, 2016 By Chelsey

Rainbow Science for Kids: Homemade Spectroscope

Make a homemade spectroscope with a few simple materials and explore the spectrum of different light sources. You’ll see all kinds of rainbows ! This science activity for kids makes a great addition to a unit on light or weather and is perfect for St. Patrick’s Day too!

Follow our Science for Kids Pinterest board!

Light experiments are always fun, especially when they involve rainbows!  In this science activity kids will make their own spectroscope- an instrument used to split light into different wavelengths, which we see as different colors of the rainbow. (This post contains affiliate links.)

Be sure to check out our other light experiments for kids:

Exploring Prisms

Rainbow Reflections

Exploring Reflections in Mirrors

How to Make a Homemade Spectroscope

Materials for homemade spectroscope.

• Empty paper towel roll
• Craft knife  and/or scissors
• Blank or old CD
• Small piece of cardboard or cardstock
• Paint (optional)

Making a Homemade Spectroscope

1. If you’ll be painting your paper towel roll, you’ll want to do that first and let it dry. (This step isn’t necessary, but it’s hard for us to pass up an opportunity to paint something!)

2. Use a craft knife (an adult should do this) to cut a thin slit at a 45° angle toward the bottom of the cardboard tube.

3. Directly across from the slit, make a small peephole or viewing hole using your craft knife  (another step for an adult).

4. Trace one end of your paper towel roll onto your small scrap of cardboard or cardstock . Cut it out.

5. Cut a straight slit right across the center of your cardboard circle.

6. Tape the circle to the top of your spectroscope.

7. Insert the CD into your 45° angled slit with the shiny side facing up.

Using the Homemade Spectroscope

Start by taking your spectroscope outside. Point the top slit up at the sky (NOT directly at the sun). Look through the peephole. You will see a rainbow inside!

Now try your spectroscope with other light sources like fluorescent light, neon light and candle light. Compare what you see!

What’s going on?

A CD is a mirrored surface with spiral tracks or pits. These tracks are evenly spaced and diffract light (separating the colors). Because the CD’s surface is mirrored, the light is reflected to your eye.

See More Science Activities Here!

Be sure to check out all our science activities for kids .

Be sure to check out STEAM Kids book and ebook for even more creative STEM and STEAM ideas!

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• Why We’re Unique

Introduction: (Initial Observation)

When white light is directed into a prism, a pattern of brilliant colors come out the other side. But how does this work? And does it help explain color and light?

Many other properties or applications of light can be researched into this project.

Some of the sub titles that you can choose to be the main focus of your research about light are as follows:

• Compare the intensity of light from different light sources. To do this you may need to purchase a light meter or build one. You then expose your light meter to different sources of light and record the results.
• How does color affect the absorption and reflection of light? Get a few glass thermometers and cover the bulb of thermometers with different color paints. Let them dry and then place them under the sunlight and record the temperatures after about 5 minutes.
• How does the intensity of light changes by distance? Record the intensity of light at different distances from a light source. Record the results and draw a graph.
• How does a surface condition affect the light reflection? Get a shiny piece of steel or aluminum and test the light reflection on that using a laser pointer. Then scratch the surface using a sand paper to see how the roughness of the surface affect the reflection of the light.
• How does a prism analyze the light? Isolate a narrow beam of sunlight and place a prism on its path until you see a color spectrum. Which colors refract more?
• What material are transparent, translucent or opaque? Use a flashlight or laser pointer in a dark room to see what material are transparent, what material are translucent and what material are opaque.
• Is there such a thing as invisible light? (Experiment 2 in this page) Use a beam of sunlight and a prism to form a spectrum of different color lights. Measure the temperature of each area and then measure the temperature of area right passed red that has no light. Excess heat in that area is an indication of an invisible radiation or invisible light known as infra red.
• Which color light is the warmest? (Experiment 1 in this page) Use a beam of sunlight and a prism to form a spectrum of different color lights. Measure the temperature of each color light and record the results.

Although it is a good choice to have a good light source for light related projects, you can often use sun light instead. Experiments can be designed to be simple and material needed for experiments can simply be purchased locally or ordered via the internet.

This project guide contains information that you need in order to start your project. If you have any questions or need more support about this project, click on the “ Ask Question ” button on the top of this page to send me a message.

If you are new in doing science project, click on “ How to Start ” in the main page. There you will find helpful links that describe different types of science projects, scientific method, variables, hypothesis, graph, abstract and all other general basics that you need to know.

Project advisor

A Note About Light

(By your Project Advisor)

What is Light?

Light is an amazing phenomena with properties unique to itself. Many scientists in the past have studied light and have used it as a valuable tool for their research. Even today light is one of the most important research subjects for scientists.

Light is the type of energy that our vision cells are sensitive to, that is why we can see where there is a light. Every substance in the world emits a special light when it is heated at high temperatures. With these special lights, scientists can identify the type of substances. With the light coming from the sun and other stars, scientists know what chemicals are available in each star.

Light is a wave of magnetic field. Many other types of radiation are also waves of magnetic fields. For example radio waves, Micro waves, Infra red, Ultra Violet and X-ray are all electromagnetic waves. The reason that we can see light and we can not see other types of electromagnetic waves is that our vision cells are not sensitive to those waves. The difference between these waves is their frequency.

What is frequency?

If you hold a magnet in your hand and start to shake it or wave it at a speed of 3 times per second, then you are producing a magnetic wave with frequency of 3 per second or 3 Hz. You may use a different method to vibrate your magnet at a rate of 20 times per second; then you are producing a magnetic wave with frequency of 20 Hz. Higher frequencies can be made using and electromagnet.

The electricity that we use at home is an alternative current at 50 Hz. In other words a flow of electrons are moving back and forth in wire at the rate of 50 times per second. If you connect such electricity to an electromagnet, it will create an electromagnetic waves with frequency of 50Hz. Radio frequencies are usually in the range of million Hz or Mega Hertz. For example a radio station may be broadcasting at 99 MHz (Read 99 Mega Hertz. Mega means million).

The frequency of visible light ranges from 430 trillion Hz, seen as red, to 750 trillion Hz, seen as violet. As you see different color lights have different frequencies.

White light is a combination of all different light frequencies.

Information Gathering:

Find out about light and its properties. Read books, magazines or ask professionals who might know in order to learn about different color lights and their differences. Keep track of where you got your information from. Click here to read some interesting facts about light, which is an electro magnetic wave. Skip any part that you don’t understand. The following is a simplified/ modified version as a quick reference.

Scientist say light is an electromagnetic wave! But, what is an electromagnetic wave? What does it mean.

Magnetism can be static like a refrigerator magnet. But when you shake or vibrate a magnet, you are creating a moving magnetic field or electromagnetic wave. Another way of making an electromagnetic wave is sending a changing (alternative) electric current into a coil of wire. The most common electromagnetic waves that we know about are radio waves. James Clerk Maxwell and Heinrich Hertz are two scientists who studied how electromagnetic waves are formed and how fast they travel.

When you listen to the radio, watch TV, or cook dinner in a microwave oven, you are using electromagnetic waves.

Radio waves, television waves, and microwaves are all types of electromagnetic waves. They only differ from each other in wavelength. Wavelength is the distance between one wave crest to the next.

Waves in the electromagnetic spectrum vary in size from very long radio waves the size of buildings, to very short gamma-rays smaller than the size of the nucleus of an atom.

Did you know that electromagnetic waves can not only be described by their wavelength, but also by their energy and frequency? All three of these things are related to each other mathematically . This means that it is correct to talk about the energy of an X-ray or the wavelength of a microwave or the frequency of a radio wave.

The electromagnetic spectrum includes, from longest wavelength to shortest: radio waves, microwaves, infrared, optical, ultraviolet, X-rays, and gamma-rays.

To tour the electromagnetic spectrum, follow the links below!

I am text block. Click edit button to change this text. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut elit tellus, luctus nec ullamcorper mattis, pulvinar dapibus leo.

Visible Light Waves

Visible light waves are the only electromagnetic waves we can see. We see these waves as the colors of the rainbow. Each color has a different wavelength. Red has the longest wavelength and violet has the shortest wavelength. When all the waves are seen together, they make white light. When white light shines through a prism or through water vapor like this rainbow, the white light is broken apart into the colors of the visible light spectrum.

How do we “see” using Visible Light?

Cones in our eyes are receivers for these tiny visible light waves. The Sun is a natural source for visible light waves and our eyes see the reflection of this sunlight off the objects around us. The color of an object that we see is the color of light reflected. All other colors are absorbed.

Light bulbs are another source of visible light waves.

Question/ Purpose:

What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.

When we feel cold, we walk to a sunny space to use the heat of sunlight. Now that we know sunlight is a combination of different color lights, it is good to know which of these color lights carry more heat energy or which color light is warmer.

Question: How do different color lights vary in the amount of heat energy that they carry? Which color light is the warmest?

Identify Variables:

When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.

Independent variable (also known as manipulated variable) is the color of the light.

Dependent variable (also known as responding variable) is the amount of heat carried by each color light.

Hypothesis:

Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis. Following is a sample hypothesis:

I think red color is the warmest light. My hypothesis is based on my observation of some electric heaters that have a heat lamp as the source of heat and the heat lamps are red.

Experiment Design:

Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”

Experiment 1:

Determine which color light is the warmest.

Introduction: In the year 1800, Sir William Herschel performed this experiment and it led to discovery of an invisible light called infrared. Herschel passed sunlight through a prism. As sunlight passes through the prism, the prism divides it into a rainbow of colors called a spectrum. A spectrum contains all of the colors which make up sunlight. Herschel was interested in measuring the amount of heat in each color. To do this he used thermometers with blackened bulbs and measured the temperature of the different colors of the spectrum. He noticed that the temperature increased from the blue to the red part of the spectrum. Then he placed a thermometer just past the red part of the spectrum in a region where there was no visible light and found that the temperature there was even higher. Herschel realized that there must be another type of light which we cannot see in this region. This light was called infrared. Here you repeat William Herschel’s experiment to see how different are the temperatures of different color lights.

You need an equilateral glass prism, 3 alcohol thermometers, scotch tape, a white piece of paper and a south facing window sill or a box. The cost of the prism we used was about $7.50 (from MiniScience.com) and the thermometers were 75 cents a piece (from a hardware store). You will need to blacken the bulbs of the thermometers so it will absorb the heat energy from light waves. To do this you can insert the bulb of thermometers in black paint and then let it dry. Alternatively you may mask the thermometers with masking tape exposing only the bulbs and then spray paint the bulbs with a flat black paint.

In the above image you can see how to set up this experiment for use outdoors. Place a white piece of paper at the bottom of a cardboard so the bottom of box does not get so hot. Rotate the prism until a good wide spectrum appears on the white paper at the bottom of the box and then tape the prism into place. To get a good spectrum you may have to tilt the box up on the prism end by placing a rock under it.

First check the temperature of the thermometers away from the spectrum in the shaded area of the box. The above image shows the temperature before the thermometers are placed in the spectrum. All 3 thermometers must read the same temperature.

If you only have one thermometer, place the thermometer bulb in blue section of spectrum, hold it there for about one minute and then read the temperature while the the blackened bulb of the thermometer is still in the blue section. Record the temperature. Repeat this with green section, yellow section and red sections of spectrum.

Record your results in a table like this:

If you have three or more thermometers, you may place them or tape them all at the same time at the bottom of the box in a way that each thermometer measures the temperature of a different color.

It takes a few minutes for the temperatures to reach their final value. Within 1 minute you can already see a difference in temperature. The differences between the 3 temperature readings continue to grow larger until the final temperatures are reached.

You may want to use a larger cardboard to make shade over your experiment setup. In this case you must cut an opening not larger than your prism so the sunlight will get to the prism while all other areas are still in shade.

Finally use your results table to draw a graph.

This project require sunlight and is really good for hot sunny days. In a cold windy day, all the heat of sunlight will be immediately removed by the wind. The solution to that is covering the box with glass or clear plastic.

Experiment 2:

Is there such a thing as invisible light?

Repeat the previous experiment, but this time also measure the temperature immediately before the purple and immediately after the red light. These areas have no visible light; however their temperature may indicate presence of invisible radiations separated from the sunlight by the prism. Record your results in a table like this:

Does your results show presence of Infrared radiations in sunlight?

Note: Presence of Ultraviolet light may not be observed in this way because UV does not create noticeable amounts of heat.

Materials and Equipment:

Complete list of material can be extracted from the experiment section.

• Prism (See samples of prisms at MiniScience.com)
• Thermometer (See samples of thermometers at MiniScience.com)

Results of Experiment (Observation):

Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.

Sample Results:

The thermometer in the blue part of the spectrum shows the lowest reading which is not much higher than shade temperature. The yellow part of the spectrum is showing a much higher temperature than the blue. The thermometer on the right, which is in the dark region just past the red, is showing the highest temperature of all 3 regions.

• The differences between the temperatures of the colors of the spectrum vary with the width of the spectrum, which depends on time of day, and the distance from the prism, which is proportional to the height of your box. In all cases the trend of temperature increasing from blue to infrared should still show up.
• All the wavelengths farther than the infrared are compressed to a small region just beyond the red (see Reconciling The Herschel Experiment ). For typical box depths of 0.3 m, no solar wavelengths are beyond 0.4 cm from the end of the red, so the “infrared” thermometer must be placed immediately next to the end of the observed spectrum.
• If you can arrange to have the prism more distant from the projected spectrum, the wavelengths will be spread out farther, giving more room to explore the infrared. However, the difference in the thermometer readings will be smaller since they will intercept less energy.

Herschel’s experiment was important not only because it led to the discovery of infrared light, but also because it was the first time that someone showed that there were forms of light that we cannot see with our eyes. As we now know, there are many other types of light that we cannot see and the visible colors are only a very small part of the entire range of light which we call the electromagnetic spectrum.

Calculations:

No calculation is required for this project.

Summery of Results:

Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.

It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.

Conclusion:

Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.

Related Questions & Answers:

What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.

Do you have infrared light at home?

Most people have a TV remote controller, wireless mouse or laptop computers that use infrared to communicate. Infrared lights are often covered with a dark glass or plastic.

Possible Errors:

If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.

If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.

References:

List of References

Speed of light.

http://sd.znet.com/~schester/calculations/herschel/index.html

Light Spectrum

It is always important for students, parents and teachers to know a good source for science related equipment and supplies they need for their science activities. Please note that many online stores for science supplies are managed by MiniScience.

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Science Project

UV Beads Experiment & The Electromagnetic Spectrum

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This UV beads experiment is a super-popular activity with kids. To help students understand why the beads change color, they need to understand ultraviolet light.

While studying the electromagnetic spectrum, you may want to add a study of solar energy or this sun print activity –it dovetails nicely with the uv bead experiment in this post.

UV Beads Experiment and The Electromagnetic Spectrum

Microwaves, cell phones, and RADAR are modern-day inventions that utilize the electromagnetic spectrum, but the fundamental groundwork for the study of electromagnetic waves started with the ancient Greeks, who first discovered static electricity. In the 11th century, the Chinese described magnetic properties.

However, it wasn’t.t until the 1800s when James Clerk Maxwell claimed electricity and magnetism were related.

He established some basic facts and equations to prove his theories. He believed:

• An electrical charge creates a field
• Magnets have two poles, North and South
• A magnetic field creates an electric current
• An electric current creates a magnetic field.

In addition, Maxwell said waves of energy existed and traveled at the speed of light (Scientists had started to study this as well). He claimed that visible light wasn’t the only form of electromagnetic energy.

Many people thought Maxwell and his ideas were wrong, but scientists proved Maxwell was correct.

One such scientist was Henry Hertz. In 1888 he discovered radio waves. Unfortunately, he died at the young age of 36.

Other scientists and inventors, such as Nikola Tesla and Guglielmo Marconi, used Hertz’s discovery to patent many inventions.

What is the Electromagnetic Spectrum?

Do you use a microwave, radio, cell phone, or television? These objects use at least one form of electromagnetic wave. Man-made objects may use electromagnetic waves to function, but the Sun and other objects in the universe emit electromagnetic radiation. To understand the electromagnetic spectrum, we will first define electromagnetic radiation. Let’s start with the term electromagnetic . Electromagnetic is another word for light.

Light is fluctuations in the electric and magnetic fields. Stars, planets, and the Sun all have magnetic fields. In fact, all objects with a temperature above absolute zero radiate electromagnetic radiation. Even ice cubes emit thermal radiation!

Electromagnetic radiation is energy emitted in the form of particle waves. Unlike sound waves, electromagnetic waves do not need air or water in which to move. In fact, electromagnetic waves are the only form of waves that can travel through empty space, such as the vacuum of the universe. In addition, all electromagnetic waves move at the speed of light. How fast does light travel?

The speed of light is approximately 299,792,458 meters per second (or about 186,282 miles per second). This is a fundamental constant of nature and is the maximum speed at which any form of energy or information can travel through space.

Scientists can determine what stars are made of by using a spectroscope to analyze the electromagnetic radiation emitted by the star.

Electromagnetic radiation is energy traveling in the form of particle waves and carrying a certain amount of energy. This amount of energy varies.

Radio waves are the weakest, and gamma rays are the strongest. Energy is directly related to temperature. Longer waves have a lower frequency and contain less energy. Shorter waves have a higher frequency and contain more energy.

The size of the waves in the electromagnetic spectrum range anywhere from the size of mountains to the size of atoms, and even smaller. Radio waves are big, and the antenna on your radio is as big as the radio waves it receives. Microwaves are small enough to fit and be useful in a microwave oven.

Infrared can be detected in something as small as the scope of a rifle. Radio and microwaves won’t hurt you. Infrared you can feel as heat. Ultraviolet-A and UV-B can burn you easily and cause enough cell damage in your skin that mutations from the damage can lead to cancer. X-rays are given to you in small enough doses by a radiologist (For example, if you break a bone and need X-rays.) that you are not injured. But think about it; the x-rays pass right through your body and expose the film on the other side of you, and they cover you with a lead shield to keep your exposure to a minimum. Gamma rays are what a Geiger counter detects and are what we think of as nuclear radiation.

Night vision goggles can detect a human being’s body in complete darkness. We think of it as complete darkness because we cannot see any visible light. However, our bodies are infrared radiators, given our body temperature of 98.6°F (On average. Some people will register a slightly lower body temperature while others register a higher temperature.). In most parts of the world, the ambient temperature is less than 98.6°F, so, our bodies are brighter sources of infrared radiation than the environment and stand out like light bulbs. Infrared radiation is an indicator of a relatively low level of energy or heat.

Scientists use radio telescopes to detect X-ray emissions throughout our universe. Sources of X-ray radiation are extremely hot. The events that cause the release of X-radiation are usually violent and unimaginably powerful. X-rays indicate high levels of energy or heat.

Visible Light Spectrum

Visible light is part of the electromagnetic spectrum that we can see using our unaided eyes.

Sometimes you might hear the term white light. The light has color, but we cannot see the colors until we view a rainbow in the sky or direct the light through a prism.

The prism splits the white light into wavelengths of a different color. In a rainbow, the water droplets in the atmosphere act as a prism. Each individual wavelength within the spectrum of visible light wavelengths is representative of a particular color. When the light of that particular wavelength strikes the retina of our eye, we perceive that specific color sensation. When all of the colors strike our retina at the same time, we perceive white. Thus, the name white light.

This chart shows the colors within the visible light spectrum. Again, as with the entire electromagnetic spectrum, the shorter the wavelength, the greater the energy and temperature. The wavelengths in the visible light spectrum range in length from approximately 780 nanometers (7.80 x 10-7 m) down to 390 nanometers (3.90 x 10-7 m).

Sir Isaac Newton discovered that shining white light through a prism separated the wavelengths and displayed the true colors. This phenomenon is called dispersion.

You will see the visible light spectrum and the color associated with it. You may already know the phrase ROYGBIV to help remember the color and order of the waves in the visible light spectrum. (red, orange, yellow, green, blue, indigo, and violet).

Why Can’t We See UV Rays or Infrared Light?

We know that the light waves on the visible portion of the electromagnetic spectrum are detected by the rods and cones in our eyes. This stimulation causes an electric pulse to be sent to our brain, where our brain interprets the information as. “I am seeing red.” or “I am seeing blue.”

Why doesn’t our brain generate the message, “I’m seeing UV rays?” There are radio waves, ultraviolet rays, and infrared rays all around us. Why can’t we see them?

Simply put our rods and cones cannot detect the wavelengths of any of the other waves on the electromagnetic spectrum. Our eye receptors are not sized to receive the wavelength of gamma rays, ultraviolet light, infrared, or radio waves. Human eyes are the perfect size for only detecting and seeing the wavelengths in the visible or white light portion of the spectrum.

Scientists have developed infrared goggles to help the military carry out night operations. Night vision goggles have a lens that can turn infrared light into a wavelength that rods and cones can see and turn into an electrical message that can be sent to the brain for interpretation. These infrared sensing lenses are colored amber or green, so we can see infrared light. However, infrared light is not naturally amber or green.

If radio, infrared, and ultraviolet rays are all around us, why don’t we get burned?

If all of these waves of energy are bombarding the Earth from space, how can humans, animals, and plants continue to survive?

Approximately 29% of the solar energy reaching the top of the Earth’s atmosphere is reflected back to space by clouds, atmospheric particles, and reflective surfaces like sea ice and snow.

Water vapor, dust, ozone absorb about another 23% of the incoming solar energy.

About 48% of the solar energy passes through our atmosphere and is absorbed by the Earth’s surface (this is described in detail below.)

This means that approximately 71% of the incoming solar energy is somehow absorbed by the Earth and its systems.

The Earth’s atmosphere protects against certain types of electromagnetic radiation, including radio waves, infrared radiation, and some ultraviolet (UV) radiation. The extent of this protection varies depending on the specific wavelength of the radiation.

Radio waves: The Earth’s atmosphere is transparent to most radio waves, allowing them to pass through with minimal absorption or scattering. This is why we can receive radio signals from distant sources. The atmosphere does interact with extremely low-frequency (ELF) waves, but they are not harmful to human health.

Infrared radiation: The Earth’s atmosphere contains water vapor and carbon dioxide molecules that can absorb and re-emit infrared radiation. This absorption helps to prevent excessive heating of the Earth’s surface by trapping some of the infrared energy and contributing to the greenhouse effect. However, the atmosphere is not completely opaque to infrared radiation, and a significant amount of it can still reach the surface. This is why we feel the warmth from the Sun and other sources of infrared radiation.

Ultraviolet (UV) radiation: The Earth’s atmosphere provides protection against a substantial portion of the Sun’s UV radiation.

The atmosphere is the mixture of gases and other materials that surround the Earth in a thin, mostly transparent shell. It is held in place by the Earth’s gravity. The main components are nitrogen (78.09%), oxygen (20.95%), argon (0.93%), and carbon dioxide (0.03%). The atmosphere also contains small amounts, or traces, of water (in local concentrations ranging from 0% to 4%), solid particles, neon, helium, methane, krypton, hydrogen, xenon, and ozone.

The study of the atmosphere is called meteorology.

Life on Earth would not be possible without the atmosphere. Obviously, it provides the oxygen we need to breathe. But it also serves other important functions. It moderates the planet’s temperature, reducing the extremes that occur on airless worlds. For example, temperatures on the moon range from 120 °C (about 250 °F) during the day to -170 °C (about -275 °F) at night. The atmosphere also protects us by absorbing and scattering harmful radiation from the sun and space.

The ozone layer is located in the stratosphere, approximately 10 to 50 kilometers above the Earth’s surface, and plays a crucial role in absorbing UV-B and a portion of UV-C radiation. The ozone molecules absorb the high-energy UV radiation, preventing it from reaching the Earth’s surface. This protective layer shields us from the most harmful UV radiation, which can cause sunburn, skin damage, and an increased risk of skin cancer.

In addition to the ozone layer, other atmospheric components, such as water vapor and clouds, scatter and absorb some of the Sun’s radiation, further reducing the amount of energy reaching the Earth’s surface.

The Earth’s atmosphere also acts as an insulator, trapping some of the heat energy from the Sun and preventing it from escaping back into space. This natural greenhouse effect helps to maintain a relatively stable temperature range on Earth, making it suitable for life as we know it.

How does our atmosphere absorb electromagnetic energy?

The Earth’s atmosphere, you know that the stratosphere contains the ozone layer about 10-25 miles above the surface of the Earth.

The shape of an ozone molecule is such that it interferes with the waves in the ultraviolet band in the electromagnetic spectrum. Thus, the ozone layer is able to block some of the UV rays. Unfortunately, if you’ve ever suffered from sunburn, you know that some UV rays do get through the stratosphere and its ozone layer.

The second reason why we are protected from electromagnet energy is that the energy is not coming at us in a heavy bombardment. For example, if a friend had a toy gun that shot plastic balls, shooting one lightweight plastic ball at your leg wouldn’t hurt. However, if your friend fired off thousands of plastic balls at one time, you would feel pain in your leg!

The amount of electromagnetic radiation coming at us is NOT so intense as to cause harm. The Earth’s atmosphere, clouds, and the Earth’s surface have reflected about 30% of the electromagnetic radiation coming at the Earth. This is why X-ray and infrared telescopes are placed on high mountain tops or in orbit. Our atmosphere blocks out a large portion of these waves that telescopes cannot obtain optimal readings.

The Earth’s Albedo

The amount of radiation reflected back into space from the Earth’s surface and atmosphere is known as the Earth’s albedo. The Earth’s albedo varies depending on several factors, including the type of surface (land, ocean, ice), cloud cover, and atmospheric composition. On average, about 30% of the incoming solar radiation is reflected back into space.

Albedo is a measure of the reflectivity of a surface or object. It quantifies the percentage of incoming solar radiation that is reflected back into space. The term “albedo” is derived from the Latin word for “whiteness” and is often used in the context of the Earth’s energy balance.

Albedo is expressed as a value between 0 and 1, or as a percentage between 0% and 100%. A value of 0 means that the surface absorbs all of the incoming radiation, while a value of 1 (or 100%) indicates that all of the radiation is reflected.

Different surfaces and materials have different albedo values. Generally, surfaces that are lighter and more reflective have higher albedo values, while darker surfaces have lower albedo values. For example, fresh snow and ice have high albedo values because they reflect a significant amount of sunlight, whereas forests and oceans have lower albedo values because they absorb more radiation.

Albedo is an important factor in the Earth’s climate system. It affects the amount of solar energy absorbed or reflected by the Earth’s surface and atmosphere, influencing temperature patterns and climate. Changes in land surface conditions, such as melting ice or changes in vegetation cover, can alter the Earth’s albedo and have implications for climate change.

Here is a breakdown of the average albedo values for different surfaces and components:

• Land surfaces: Land surfaces have varying albedo values depending on factors such as vegetation cover, soil composition, and surface color. On average, land surfaces reflect about 10-30% of the incoming solar radiation.
• Ocean surfaces: The albedo of ocean surfaces depends on several factors, including the angle of sunlight, wind speed, and the presence of waves or currents. On average, oceans reflect about 6-20% of the incoming solar radiation.
• Snow and ice: Snow and ice have high albedo values, reflecting a significant portion of the incoming solar radiation. Fresh snow can reflect up to 80% of the radiation, while sea ice reflects about 30-50%.
• Clouds: Clouds play a crucial role in the Earth’s energy balance. They reflect a substantial amount of incoming solar radiation back into space. The albedo of clouds varies depending on their thickness, altitude, and composition. On average, clouds reflect about 30-80% of the incoming solar radiation.

UV Beads Experiment

UV beads are usually made of a type of plastic called polystyrene, which contains a special type of dye that is sensitive to ultraviolet light. The dye molecules in the uv beads change their shape and absorb UV radiation when exposed to sunlight or other sources of UV light, causing the uv beads to change color.

Where to Buy UV Beads

Over the years, I have purchased several different brands of UV beads. Two different brands are listed below.

Make a UV Beads Bracelet

• UV beads At a minimum, I recommend giving each child 12 uv beads. The bead colors vary, so a minimum of 12 ensures they get at least one of each color.
• Chenille sticks

Instructions

• Give each student at least 12 beads.

In this video, the students covered up the uv beads with black construction paper and then white. When the uv beads were uncovered, they coloring changed quickly, so we have slowed down the video to show how much the uv beads did fade under the paper.

UV Beads Experiment – Light vs. Dark Covering

We tried several UV beads experiments. In one experiment the kids created, we covered our uv beads with black construction paper vs. white constructions paper.

Since dark surfaces absorb more light than white surfaces, because they have a higher level of pigment or color, we hypothesized that when we covered the uv beads with the dark paper, the beads would get more pale than when they were covered with white paper.

When light hits a surface, it is either reflected, absorbed, or transmitted. Dark surfaces appear dark because they absorb most of the light that hits them, while white surfaces appear white because they reflect most of the light that hits them.

We know that light is made up of electromagnetic waves that have different wavelengths and energies. When light hits an object, the object’s color or pigment absorbs some of the wavelengths and reflects others. Dark surfaces have more pigment, which means they absorb more of the wavelengths of light that hit them, while white surfaces have less pigment, which means they reflect more of the wavelengths of light that hit them.

So, we were hoping to see a very obvious difference in the uv beads, even when we slowed down the video on the replay. Most of the students said they noticed that the uv beads were lighter when the black paper was lifted from the beads vs the white paper. We agreed we needed to do more testing.

We also discussed some factors that may have come that perhaps we need to control in another experiment like this. In addition to the color of the surface, the texture and angle of the surface can also affect how much light is absorbed or reflected. Rough surfaces tend to scatter light in different directions, while smooth surfaces tend to reflect light in a more predictable manner. The angle of the surface can also affect how much light is absorbed or reflected, as surfaces that are angled away from a light source will reflect less light than surfaces that are angled towards the light source.

Perhaps we held the papers at different angles? Could that have accounted for the difference.

There are a lot of different ideas and hypotheses to test in a uv beads experiment.

Additional Resources to Use with UV Beads Experiments

• NASA has online lessons, as well as some ebooks on the electromagnetic spectrum. These are definitely for grades 8-12.
• The Science of Light and Color for Kids video from Free School

I hold a master’s degree in child development and early education and am working on a post-baccalaureate in biology. I spent 15 years working for a biotechnology company developing IT systems in DNA testing laboratories across the US. I taught K4 in a private school, homeschooled my children, and have taught on the mission field in southern Asia. For 4 years, I served on our state’s FIRST Lego League tournament Board and served as the Judging Director.  I own thehomeschoolscientist and also write a regular science column for Homeschooling Today Magazine. You’ll also find my writings on the CTCMath blog. Through this site, I have authored over 50 math and science resources.

Look! We're Learning!

Early Learning. Happy Teaching.

Simple Science Experiments: Simple Light Refraction Experiment

December 28, 2017 by Selena Robinson 9 Comments

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We’re continuing with our simple science experiments this week by taking a look at light refraction. I found a great light refraction experiment video on YouTube and decided to try it with Tigger.

Full disclosure: I didn’t know that refraction was what this experiment demonstrated. I actually had to look it up first. But the experiment is super easy and quick, so that’s a big plus!

Check out this easy way to teach kids about light with this simple light refraction experiment !

And, if you like this one, try some of our other science activities, including how to make an egg float and our easy heat conduction experiment !

Simple Light Refraction Experiment

Watching the original light refraction experiment on YouTube will give you a great look at what’s involved in this activity. But you really only need four things:

• A sticky note (I used a Post-It)
• An empty transparent bottle

Draw two arrows on a sticky note. Make sure that each arrow points in a different direction. Stick the note to a blank wall.

Next, fill up the water bottle. Oh – put the lid on before you do this too! You don’t want water spilling out when you move the bottle around…lol.

The alternating arrows on the note point to the left and the right. Let the kids gradually move the water-filled bottle in front of the sticky note. As the bottle moves in front of the sticky note, something amazing happens.

The arrows appear to change direction! The top arrow, which points to the left, appears to point to the right. And the bottom arrow, which points to the right, appears to point to the left!

Move the bottle back to see the arrows return to their original directions.

So what exactly is going on? We learned that refraction occurs because light bends when it passes through substances, such as water and plastic.

As the light travels through a substance, it becomes concentrated into a focal point, usually near the center. After light passes through the focal point, the rays cross over each other and cause images to appear reversed.

Turns out you can’t believe your eyes after all! 🙂

Books with Simple Science Experiments:

If you liked this simple science experiment, take a look at these books with even more easy activities! (Affiliate links provided here for convenience. For details, see our Disclosure Policy .)

• Science is Simple: Over 250 Activities for Preschoolers
• 365 Simple Science Experiments with Everyday Materials
• The Everything Kids’ Science Experiments Book
• Safe and Simple Electrical Experiments

Don’t miss the rest of our Simple Science Experiments!

For more science homeschooling ideas, follow my It’s Science board on Pinterest!

P.S. Get more fun learning ideas in our email newsletter!

July 13, 2014 at 5:11 pm

I love this demonstration. Must do it again with my kids! Amazing how much you can learn and do with simple household objects!

August 3, 2014 at 1:43 am

Light refraction and how it moves is really so cool. Thanks for linking up to Science Sunday (even when I’m behind on commenting).

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Science Experiment for Kids: Light Box Magic

Introduction: Science Experiment for Kids: Light Box Magic

Step 1: Motivate

Step 2: gather materials.

Step 3: (Optional) Let the Kids Paint the Box

Step 4: Fill the Bottles With Water. for More Fun Add Food Coloring to Some of the Bottles.

Step 5: Trace the Bottom of the Bottles on the Top of the Box and Cut Holes.

Step 6: Cut a Hole in the Side of the Box to Look Inside.

Step 7: Push Bottles Into Holes and Let the Experimenting Begin!

Step 8: Explain the Science Behind It

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Milk and the Light Bulb

• February 29, 2024

As an enthusiastic preschool teacher, I am always on the lookout for fun and educational science experiments to engage my littles. . Recently, I came across a fascinating experiment on the Internet that promised to combine art, chemistry, and a touch of magic. Eager to try it out, I gathered my little scientists and embarked on what seemed like an exciting adventure. Little did I know that this experiment would teach us a valuable lesson about the importance of critical thinking and not trusting everything we read online.

The experiment involved placing milk in a shallow dish and adding drops of food coloring around the edges. A lightbulb was to be placed in the center, and finally, a drop of dish soap was added to the mixture. According to the instructions, the lightbulb was supposed to light up, creating a mesmerizing display of colors as the dish soap interacted with the milk and food coloring.

With anticipation and excitement, we followed the steps meticulously. The children’s eyes sparkled with wonder as they watched the food coloring mix and create captivating designs in the milk. However, the much-awaited moment of the lightbulb lighting up never came. We were left perplexed, scratching our heads, wondering what went wrong.

Upon reflecting on our failed experiment, I decided to delve deeper into the science behind it. As it turns out, the experiment we attempted is a popular one known as the “Milk and Soap Experiment” or “Milk Magic.” The dish soap, when added to the milk, disrupts the surface tension of the liquid. This causes the fat molecules in the milk to move, creating a swirling motion that carries the food coloring along with it, resulting in the mesmerizing patterns we observed.

However, the claim that the lightbulb would light up was where the experiment fell short. The Internet can sometimes be a source of misleading or inaccurate information, and this experiment was a prime example. The idea that the dish soap and milk mixture would conduct electricity and light up the bulb is simply not scientifically accurate.

I will add the video to our group.

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CERN experiment helps narrow the hunt for dark matter

• Astronomers have long observed that galaxies rotate faster than expected, suggesting the presence of an unseen substance called dark matter. 
• Despite extensive efforts, no direct evidence of dark matter has been found, prompting CERN scientists to use the NA64 facility to search for lighter forms of dark matter using high-energy muons. 
• The initial results have ruled out some dark matter scenarios, and future improvements in the experiment may enhance the chances of detecting this elusive substance.

Over the past half-century, astronomers have faced an embarrassing problem: Galaxies rotate too fast. When astronomers measure the speed of stars on the outskirts of galaxies, they are much higher than expected. It’s as if a cloud of invisible matter surrounds nearly every galaxy in the Universe. This matter interacts gravitationally and neither absorbs nor emits light. Astronomers even have a name for this ghostly substance: dark matter. 

The problem is that, despite decades of efforts, no direct evidence of dark matter has been observed. Scientists working at the CERN laboratory in Europe have created a facility that will provide new capabilities in the search for this elusive substance. They recently released their first results.

Using the CERN NA64 facility, scientists employed a high-energy beam of muons to search for a form of dark matter that has been overlooked by previous searches. This effort follows in the footsteps of a long history of experiments searching for dark matter with specific properties.

While the evidence of the rapidly spinning galaxies is very strong evidence that dark matter exists, its properties are unknown, with the possible mass of individual dark matter particles spanning an enormous range. On the light side, one theory proposes that individual particles have a mass much lower than an electron. On the heavy side, individual dark matter particles could be 30 times the mass of the Sun. 

Since the 1990s, various experiments have ruled out some possibilities; for example, most scientists now rule out very heavy dark matter, preferring models in which individual dark matter particles are atomic or smaller in size. In the early 2000s, the scientific community favored models in which dark matter particles were in the range of the mass of a proton to as much as a few thousand times heavier than that. However, with the 2010 start of operations of the Large Hadron Collider , the world’s most powerful particle accelerator, dark matter of this form is becoming increasingly disfavored. 

The NA64 facility was designed to look for possible lighter forms of dark matter. Rather than attempting to detect it directly, the NA64 experiment relies on the fact that dark matter doesn’t interact with ordinary matter as a way to detect it.

Energy conservation is a central principle of physics. It says that energy can neither be created nor destroyed. If you measure the energy of a system at one time, it will remain the same, no matter what happens. It’s like a bank account that doesn’t pay interest. Whatever you deposit, you can take out. If the two numbers don’t balance, somebody stole some of your money. 

The basic principle of the NA64 experiment is similar. High-energy muons crash into a target, interacting with atomic nuclei. After the collision, the energy of the debris is measured. If the energy after the collision is less than the energy before the collision, then the energy has somehow escaped, undetected. One possibility is that a dark matter particle was created. Because dark matter doesn’t interact, it would have traveled through the detector without interacting. Essentially, you know it’s there because you didn’t see it.

The NA64 experiment looked for dark matter in the range of about 0.5% to 50% of the mass of a proton. Besides being a range of masses that had not been fully explored using a muon beam, this range was fortuitous for other reasons as well.

Muons are essentially heavy electrons. They have the same electric charge and spin characteristics as electrons, but muons are heavier. Having both electric charge and spin means that muons act like tiny magnets and the magnetic properties of muons have been mysterious for the past couple of decades. The name given to this magnetic property is “muon g-2,” and scientists have both predicted and measured muon g-2 very precisely. They agree, digit for digit, for seven digits, and then disagree in the eighth. The measurement was made by the Muon g-2 collaboration , and the prediction was made by the Muon g-2 Theory Initiative .

Having data and prediction disagree is not inherently surprising. After all, measurement and theoretical prediction rarely agree exactly. However, if the theory is correct and the measurement is accurate, the two should be close and should agree within the stated uncertainties.

Future experiments

The most recent measurement and prediction do not agree with the stated uncertainties, and this has set off a firestorm of discussion in the scientific community. When very precise predictions and measurements disagree, it is often a sign of an impending discovery. Thus, any measurement of muons could help resolve the situation.

The NA64 collaboration studied 20 billion muon collisions, looking for collisions with the right amount of missing energy. None were observed. This result has both ruled out a range of dark matter scenarios, as well as ruled out certain explanations for the muon g-2 mystery.

The NA64 experiment is still being developed and future improvements are expected to create a thousandfold increase in the number of muons to be studied. In tandem with the increased beam, improved equipment will result in a tenfold reduction in measurement uncertainties associated with mismeasuring muon energy. When these two improvements are achieved, the resulting apparatus will significantly improve the experiment’s capabilities and it is possible that future measurements could find the elusive dark matter.

DARPA's military-grade 'quantum laser' will use entangled photons to outshine conventional laser beams

Prototype quantum photonic-dimer laser uses entanglement to bind photons and deliver a powerful beam of concentrated light that can shine through adverse weather like thick fog.

Researchers are developing a new, military-grade "quantum laser" that can cut through fog and operate across long distances.

The U.S. Defense Advanced Research Projects Agency (DARPA) has awarded a $1 million grant to scientists building a prototype "quantum photonic-dimer laser" that uses quantum entanglement to "glue" light particles together and generate a highly concentrated laser beam.

Lasers play a crucial role in military operations and are used in everything from satellite communications and targeting technology to mapping and tracking systems like lidar (light detection and ranging).

Conventional lasers work by stimulating electrons in atoms to oscillate in unison. When these electrons move from a high-energy state to a low-energy state, they release a form of light called "coherent light" — light with uniform wavelength and phase. As this light is bounced between mirrors inside the laser device, it is refined into a concentrated laser beam.

But by using entangled photons, the quantum photonic-dimer laser can maintain precision and strength over greater distances and in adverse conditions, the scientists said in a statement . Quantum lasers could therefore provide better performance for military applications like surveillance and secure communications in harsh environments.

"Photons encode information when they travel, but the travel through the atmosphere is very damaging to them," project lead Jung-Tsung Shen , associate professor of electrical & systems engineering at Washington University in St. Louis. "When two photons are bound together, they still suffer the effects of the atmosphere, but they can protect each other so that some phase information can still be preserved."

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The two-color photonic dimer laser works by bonding pairs of photons —  fundamental particles that represent the smallest building blocks of electromagnetic radiation — through a process called quantum entanglement .

Quantum entanglement is a strange and complex phenomenon in the field of quantum mechanics that occurs when two or more particles become interconnected in such a way that one particle instantly influences the state of the other ­— regardless of the distance between them. 

When two photons are linked together through quantum entanglement, they create what are known as photonic dimers, the researchers said. These pairs of photons are easier to manipulate because they act as a single entity, with any change applied to one photon directly affecting the other.

— 'Quantum-inspired' laser computing is more effective than both supercomputing and quantum computing, startup claims

— China creates its largest ever quantum computing chip — and it could be key to building the nation's own 'quantum cloud'

— Ultrafast laser-powered 'magnetic RAM' is on the horizon after new discovery

This binding of light particles increases the energy and stability of the laser, making it better at performing over long distances and in adverse conditions like extreme temperatures and fog.

Previous work by Shen and his team, published in December 2020, explored how quantum photonic-dimer laser technology could be used to improve deep brain imaging. In that study, they used photonic dimers to map intricate neural structures. 

The technology can also play a role in quantum computing and telecommunications, the researchers said, possibly leading to faster and more secure ways of transmitting data.

"We are trying to exploit the property of entanglement to do something innovative. The entanglement can do many things that we can only dream of — this is just the tip of the iceberg," Shen said.

Owen Hughes is a freelance writer and editor specializing in data and digital technologies. Previously a senior editor at ZDNET, Owen has been writing about tech for more than a decade, during which time he has covered everything from AI, cybersecurity and supercomputers to programming languages and public sector IT. Owen is particularly interested in the intersection of technology, life and work ­– in his previous roles at ZDNET and TechRepublic, he wrote extensively about business leadership, digital transformation and the evolving dynamics of remote work.

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It’s Dark Sky Month in Colorado. Here’s how to enjoy the stars

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Banner image: The Milky Way stretches above Great Sand Dunes National Park and Preserve in Colorado. (Credit: National Park Service)

This month, Colorado recognizes its third Dark Sky Month, an annual celebration of getting away from city lights, lying under the stars and gaping at the vastness of the universe.

Such experiences are becoming harder to find today as streetlights, headlights, neon signs and more spread around the world. According to data from the citizen science project Globe at Night , the night sky is growing about 10% brighter on average every year.

  Dimming light pollution

Check out these tips, adapted from Dark Sky Colorado , to learn how you can help keep the skies dark:

All light should have a clear purpose Consider using reflective paints or self-luminous markers to reduce the need for permanently installed outdoor lighting.

Light should be directed only to where needed Target the light beam so that it points downward.

Light should be no brighter than necessary Use the lowest light level required.

Light should be used only when its useful Use controls such as timers or motion detectors to ensure that light is available when it is needed.

Use warmer colored lights where possible Limit the amount of shorter wavelength (blue-violet) light.

But it’s not too late to experience the dark, especially in Colorado, said Erica Ellingson, professor emerita of astrophysical and planetary sciences at CU Boulder. Among other pursuits, she’s an expert in the field of archaeoastronomy , or the study of how ancient civilizations incorporated celestial bodies into their cultures.

Today, the organization Dark Skies International has certified 15 Colorado parks and towns as official Dark Sky Places. But you can still enjoy the night sky even if you can’t make it to one of these spots, Ellingson said. 

“The next couple of months with the good summer weather will be perfect for going out with friends, with family, with anyone really to share the spectacle of the sky,” she said. “The stars in Colorado are absolutely spectacular.”

She gives her take on what humans lose when we can no longer see the stars, and how beginners can jump into astronomy.

What is light pollution?

Light pollution is human-made lighting that, instead of providing light for all the useful things we have down here, gets thrown up into the sky. In most of the United States, and even worldwide, many people have never seen the Milky Way, or have never seen more than a few stars. We are losing a really, really old heritage—being able to walk outside and wonder at the stars.

Do satellites, like SpaceX’s Starlink satellites, also contribute to light pollution?

Yes, there are more and more satellites being launched every year. It’s becoming common for long telescope exposures to have a satellite streak on them, and they are noticeable in the sky even without a telescope. I’ve seen many Starlink “trains” shortly after launch. They look like a string of a dozen or more bright dots flying in a line across the sky. 

Where can people in the Front Range go to experience dark, or darker, skies?

Within the Front Range area, you’re looking for any place where you can get away from the dome of light around Denver, Boulder and some of the other larger cities. Sometimes, if you just go up the Peak to Peak Highway, the Flatirons in the foothills can block some of that light, and you can view darker skies. 

Rocky Mountain National Park doesn't have super dark skies because it's close to Denver, but it's certainly better than what you'll find in any of the cities or suburbs. 

 Colorado astronomy resources

Dark Sky Colorado Find Dark Sky Places in Colorado and learn how to reduce light pollution.

CU-STARs Check out this program that provides opportunities for CU Boulder and K-12 students to learn about space.

Sommers-Bausch Observatory Join regular Friday night open houses on the CU Boulder campus.

How can beginners get into stargazing?

Connect with a community where there are people who are willing to share their star lore. Most cities in Colorado have a group of people who are telescope and astronomy enthusiasts. They often hold open houses called “star parties” where anyone is welcome. They'll bring out all their best telescopes and are happy to tell you everything they know about what's going on in the night sky.

Here on campus, the Sommers-Bausch Observatory holds Friday night open houses in the fall and spring when classes are in session. In the summer, they have a more reduced schedule.

How did ancient civilizations approach stargazing? 

We see some practical uses in many different societies—things like using the sun, the moon and stars as timekeepers, as calendars or guides for planting. 

But we also see people looking to the stars for power and mystery. We put the best of ourselves in the sky, the things that we value, the stories that are most powerful for our culture. All of these things we tuck up into the sky, and they're available for anyone to walk out of their house and look up and see.

It seems like the best part about stargazing is sharing it with other people. Do you agree?

I always ask my students at the start of the semester to tell me about experiences they had under the night sky. What strikes me most is that they nearly always say, “I was with my mom, my dad, my friends, my cousin, my partner.” Their stories involve who they were with and how they shared the sky together. 

This is a very ancient tradition, a very ancient feeling. The skies are filled with stories, filled with wonder that we should be sharing.

CU Boulder Today regularly publishes Q&As with our faculty members weighing in on news topics through the lens of their scholarly expertise and research/creative work. The responses here reflect the knowledge and interpretations of the expert and should not be considered the university position on the issue. All publication content is subject to edits for clarity, brevity and  university style guidelines .

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How to make a coffee can camera—in 1961 and today

By Bill Gourgey

Posted on Jun 16, 2024 1:00 PM EDT

6 minute read

At about the time when coffee gained ground across the Near East in the 16th century—giving rise to coffee houses which quickly became important cultural centers—optical inventions like the compound microscope and telescope were also making their debut. Among these, the camera obscura became an essential tool for artisans to capture relatively detailed real-world images. Much later, in January 1961, Popular Science published instructions that leveraged the physics of the camera obscura to build a homemade coffee-can camera, combining unlikely staples with Renaissance origins.  It was novel then—and still is now—to use a coffee can to make a camera capable of also being a developing tank for the film, oran “instant” photo, just like a Polaroid. Let’s dive into the technique.

Popular Science and the camera obscura

The camera obscura, ancestor of the photographic camera, was typically a wooden box fitted with a lens on one side and an angled mirror inside that projected real-world images onto a frosted plate of glass or drawing paper, which could be traced by artists to capture fine details. It was Joseph Nicéphore Niépce , an inventor from France, who was among the first to transform the manual process of tracing camera obscura projections into an automated process that used chemistry to fix the image on a plate. 

The earliest surviving photo was recorded by Niépce in 1826. Soon after, he teamed up with Louis Jacques Mandé Daguerre, a Romantic Period painter, to perfect the chemical process of capturing images. In 1839, Daguerre revealed his eponymous daguerreotype, which set in motion decades of photographic innovation . Eastman Kodak introduced its popular Brownie camera in 1900 to anyone who could afford its $1 price tag.

[ Related: Inside look: This vault holds the world’s greatest collection of historic cameras ]

But even as manufactured cameras spread, homemade cameras, or pinhole cameras, modeled after photography’s ancestor, the camera obscura, remained popular. All it required was a small container, like a shoebox, and some photographic paper. In fact, more than a century ago, Popular Science started offering do-it-yourself instructions for homemade pinhole cameras. A 1918 story recommended a cardboard box with “a sheet of tinfoil and pillbox” for the lens. A needle was used to poke a hole in the tinfoil to allow light into the chamber.

The editor, John F. Mahoney, explained just how the camera worked:

“If the room is darkened except for the one light, an inverted image of the lamp filament will appear on the second sheet of cardboard, incidentally proving that light travels in straight lines. From each point on the lamp filament, a light ray passes through the hole, and registers itself on the dark sheet of cardboard. Joining together, these points of light make up the image, its size depending on the distance from the light source, which may be an open gas flame as well as an incandescent lamp.”

It’s worth noting that even though human eyes work like pinhole cameras—the pupil for the aperture, the retina for the film—fortunately for us, we don’t see the world upside down. That’s because our brain leverages myriad inputs that tell us which direction is up, thereby inverting images before they register. Plus, having two lenses (eyes) slightly separated enables us to see the world in 3D .

Toward the end of the 20th century, the chemistry of photography gave way to computational photography, simplifying and accelerating the process of capturing images. By coupling cameras with phones, photography became so accessible it sparked photo and video sensations such as Facebook, YouTube, Instagram, and TikTok, which may be too much of a good thing, according to recent reports .

Long before social media, American writer and critic Susan Sontag made no secret of her general distaste for photography, predicting that our culture would be consumed by it. In her 1977 essay “The Image-World,” she suggested that “ photographs are a way of imprisoning reality ,” of subsuming reality itself by packaging the real world into convenient, digestible chunks. In the late 1970s, when digital cameras were still the size of toaster ovens—making coffee-can cameras look sleek—her ideas were provocative. Today with smartphones in more than half the world’s hands , they seem prescient. And yet, even Sontag might have admitted that there’s something very Renaissance about imprisoning reality in a coffee can.

No doubt, snapping a photo with your phone beats whipping out your coffee can to capture those important moments, although you might elicit some startled expressions. And yet, like a Polaroid, your coffee-can camera will serve up an on-the-spot physical image (just make sure you’re not in a hurry and have some chemicals handy) that your phone can’t produce. If that notion appeals to you, these steps will liberate your repressed do-it-yourself longings. Although the original instructions date back more than half a century, all of the supplies are still readily available, thanks to—you guessed it—digital media and online shopping. 

Step 1: Build your instant camera

While the scant instructions offered in our 1961 story provide the basic parts and schematic, all of which can be obtained at grocery and hardware stores (or online), you might want to view contemporary videos like a coffee can camera tutorial and written instructions that will take you through the steps for assembling a pinhole camera, while explaining important features. For instance, it’s essential to have a chamber that is black and completely sealed from light—except when the shutter is opened to snap a picture. Note that the 1961 version includes a tube and funnel to pour in the developer and fixer solutions. (Also note that it suggests using black lacquer to coat the interior. Lacquer likely holds up against the solutions, whereas flat paint might not.)

Step 2: Prepare your film and solutions

There are several companies that still make photographic paper for film, such as Ilford . Remember, though, that whenever you work with photographic film, darkness is essential, which means cutting the paper down to size and inserting it in the camera in a dark room. If you’re working with black and white film, red light is okay to help you see what you’re doing. Otherwise, you’ll need a darkroom safelight . 

To develop the film, you’ll need developer and fixer solutions, offered by companies like Kodak and Dektol . If they’re too pricey, a video from The Royal Institution explains how to make your own homemade solutions using common household ingredients like mint, baking soda, chewable Vitamin C tablets, and lemon juice. 

Step 3: Light! Camera! Action!

Once your camera is loaded with film and ready to take pictures, some trial and error will be required to find the right exposure time, which depends on a number of factors like the size of your pinhole and the lighting—the brighter the day, the less exposure time required.

The unique feature of the 1961 coffee-can camera is the ability to use the can as the darkroom. Once you’ve taken your photo, you’ll want to pour in some developer solution through the funnel and tube, keeping the lid on tight and bending the tube to prevent light from entering. Let it set for several minutes. Again, you’ll have to find the right interval through trial and error. Pour out the developer solution through the tube then pour in some water to rinse it. After pouring out the water, you’ll want to add the fixer solution and let that sit for several minutes. At this point, it’s safe to open the can. You should see your image on the film. Rinse the can with water, carefully remove your image, and let it dry. 

For a true Renaissance experience, take your coffee-can camera down to your local café or coffeehouse and set it up. No one will get the connection, but you’ll be in good company, sipping coffee, exchanging heady ideas with friends, and snapping their portraits on your replica of a camera obscura—traditions that date back more than half a millennium.

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A black hole made from pure light is impossible, thanks to quantum physics .

A “kugelblitz” would be foiled by particles and antiparticles that carry energy away

No known source of light could even come close to concentrating enough energy to form a black hole, a new study suggests.

Basem Gamal/Getty Images

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By Emily Conover

June 24, 2024 at 9:15 am

Black holes can’t be formed from pure light. Quantum physics would curb their creation under any foreseeable conditions, a new study suggests.

Typically, matter is responsible for black holes. They’re often formed when a star’s core implodes at the end of its life. But matter isn’t necessarily required to form a black hole. According to Einstein’s general theory of relativity, black holes could form from concentrated energy alone.

A black hole formed from electromagnetic energy — that is, light — is called a kugelblitz. That concept has been jangling around in physicists’ brains for decades. But actually producing a kugelblitz  seems to be a no-go , theoretical physicist Eduardo Martín-Martínez and colleagues report in a paper accepted to  Physical Review Letters . “No known source in the current universe would be able to produce it, neither artificial or natural,” says Martín-Martínez, of the University of Waterloo in Canada.

In recent years, science fiction writers have picked up the kugelblitz mystique and run with it. Fans of the Netflix show  Umbrella Academy  may be familiar with the term, which is German for “ball lightning.” In season 3, a kugelblitz  obliterates large swaths of existence .

In general relativity, gravity results from matter curving spacetime. If enough mass is packed into one region, the spacetime can curve so dramatically that it forms a region within which it’s impossible to escape — a black hole. But in general relativity, energy and mass are equivalent. That means energy can curve spacetime just as matter can, suggesting the wild idea that a black hole could form with no matter at all.

That concept is “a very interesting thought,” says theoretical physicist Juan García-Bellido of Universidad Autónoma de Madrid, who was not involved in the new study, “especially if we want to produce something like this in the laboratory.”   Scientists have previously considered whether futuristic lasers might one day form a black hole in a lab, and even proposed using a kugelblitz  to power a spacecraft .

Alas, calculations suggest that any attempt at a kugelblitz would result in failure, Martín-Martínez says. “You are not going to get even close. You’re not going to get even something that starts attracting you like Earth would.”

That’s because of a quantum effect that occurs when electromagnetic energy is highly concentrated. According to the well-verified theory of quantum electrodynamics, when light reaches those extremes, pairs of particles and antiparticles begin to form. Those particles — electrons and their positively charged antimatter partners, positrons — would escape the region, taking energy with them. That prevents the energy from reaching the levels needed to form a black hole.

Forming a kugelblitz in a laboratory would require light intensities more than 10 50  times that of the state-of-the-art laser pulses, the team calculated. (That’s a mind-bogglingly large factor — a 1 with 50 zeroes after it.) And in nature, the brightest quasars — brilliantly luminous centers of active galaxies — are likewise vastly too dim. 

The kibosh on kugelblitzes applies across a huge range of scales. It rules out itty-bitty kugelblitzes with a radius as small as a hundredth of a quintillionth of a nanometer all the way up to 100 million meters. Even outside that range, Martín-Martínez says, a kugelblitz would still be very unlikely.

García-Bellido, however, notes a possible loophole: “It’s much more likely that things like this might have happened in the early universe.” 

Just after the Big Bang, the universe is thought to have expanded extremely rapidly, a process known as inflation. That inflation may have imprinted  fluctuations in the curvature of spacetime  that could cause light to collapse into what’s known as a primordial black hole ( SN: 8/7/16 ). So while light won’t form black holes under its own gravity, that preexisting curvature, García-Bellido says, could have allowed something akin to a kugelblitz. 

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