Light experiments for kids

Experiments to help you teach your child about light

Light is all around us. We flip a switch and it shines forth. But light is more than just a way to read a book or play a game. It is a force of nature that can tell us about our world as easily as it can tell us about what is happening down the street. As the northern hemisphere approaches the longest night of the year, it makes sense to look at light and how it affects our lives. In the following experiments, you and your child will explore how light and color are related. How it can appear to be bent and separated into colors, both in the sky and in water.

Mirror, Mirror

What You Need: A small mirror, masking tape, flashlight, paper, pen.

Mirrors reflect light. To show your child how mirrors work, there are ways to play with them. First, tape a small mirror to the wall with masking tape. Stand slightly beside the mirror, so that you can see the reflection at an angle. Ask your child to stand in front of the mirror and see if she can see your reflection. If she can’t, ask her to move to the opposite side of the mirror until she can see you. If she can, ask her to move away until your image slides off the mirror.

Then shine the flashlight into the mirror. If necessary, turn off the overhead light so that you and your child can see the flashlight better. Look around the room and spot the ball of light. Experiment with different angles to see where the light bounces. Then draw a circle on a piece of paper. Stand in one corner of the room, and ask your child to figure out where she must shine the flashlight so that the light lands in the circle. Move around and try again.

Do-It-Yourself Rainbow

What You Need: A clear drinking glass, water, white paper, a sunny day

When light passes through water, the water molecules split the light into different colors. This happens naturally when light passes through raindrops and we see a beautiful rainbow arcing across the horizon. But you don’t need to wait until a rainy day to see a rainbow, or show your child how one is formed. Instead, fill a clear glass with water. Hold the glass carefully between the sun and a sheet of paper. Move the glass until you see bands of color on the paper. Show your child how the colors are always in the same order: Red, orange, yellow, green, indigo (or dark blue,) and violet. This order is due to the fact that each of these colors has its own specific wavelength. The shorter wavelengths register as purple and blue to the eye, while the longer wavelengths appear to be red, orange and yellow.

It's All Black and White: Or Is It?

What you need: Coffee filter, scissors, colored markers, rubbing alcohol, water, a small plastic dish, a pencil or stick long enough to balance on the dish, card stock, a ruler, a hole punch, string

We see colors, especially black and white, and think that they are only that one color. These experiments will show your child that color isn’t black and white. Start by cutting a strip of coffee filter. Color a large dot on one end of the strip of coffee filter with the black marker. Mix three tablespoons of alcohol with three tablespoons of water in the bottom of the plastic dish. Tape the white end of the coffee filter to the pencil and drop the black end into the alcohol/water mixture. Watch as the filter absorbs the fluid and the ink slowly moves up the filter. Different colors in the black ink will register at different places on the filter paper. This is called color chromatography. Come back to the paper over the next several hours and see what colors emerge.

So, black ink is made of many different colors, but what about white? Try this.

Cut a circle out of the card stock. With a ruler, divide the circle into six, even, pie-shaped pieces. Color each piece in a primary or secondary color: red, yellow, blue, orange, green, and purple. Cut two holes near the center of the circle. Cut three feet of string and thread it through both holes before tying the ends together. Pull the string so that there are equal loops on both sides of the circle. Put your fingers through the loops. Spin the circle and wind up the loops, then pull. The circle will spin very fast. As the circle spins, you will see that the colors disappear, and both sides of the circle appear white.

Light Magic

What You Need: A clear glass, water, a straw, a pencil

If you have done some of the other experiments, you will already have explored how light can be reflected and bent into a rainbow. This experiment show how light is bent in other ways as well.

First, fill a clear glass with water and set it on the table. Start with a simple drinking straw. Look at the straw when it lies on the table. Show your child how it is straight. Then put the straw in the water. Look at the straw a second time. Does it still appear straight? No. It looks as though it is bent. Now move the straw to the side of the glass closest to your child. Does this change the appearance? Move the straw to the side of the glass farthest from your child. Does it look the same? Remove the straw and see if it is still straight, or if it is curved in any way. Try the same thing with the pencil. Talk to your child about how this is important. What does this mean when swimming, fishing or boating? How do people who work in the water make decisions based on the knowledge of water bending light.