Science Activity: Spectacular Spectrums

Buy this book »

Light is stranger than you might think. Light from the sun, a flashlight, or almost any other source consists of many different colors- but you usually can't see them. In this activity, you'll experiment with ways to break up ordinary light to make its invisible colors visible!

1. Get Ready

Flashlight ( A MAG-LITE, an EXCELL, or another brand of focused-beam flashlight will work best, but others will work, too.)
Audiocassette case made of clear plastic
Clear plastic cup or glass
Water
Two sheets of white paper
Transparent tape
Large assortment of colored markers or crayons
Stack of books taller than flashlight
Small table
Partner

2. Do and Wonder

In this activity, you'll try to break apart white light. To do that, you'll aim a beam of light through water in one container and then another and try to capture the spectrum each produces on a sheet of white paper. Your partner will use colored markers or crayons to draw each spectrum.

Shining Light through a Glass Containing Water

Move the table so it's against the wall. Then arrange the books on the table so they're stacked flat against the wall. Fill the glass about three-fourths full with water. Set it on top of the stack of books so part of the glass is over the edge.

Darken the room.

Your partner should be prepared to tape a sheet of white paper to the wall where the spectrum is produced.

Turn on the flashlight and hold it close to the part of the glass that extends over the edge of the book stack. Move the flashlight back and forth and up and down until you see a pattern of color somewhere on the wall or floor. (The pattern won't be very large and will probably be at the edge of a circle of white light.)

Your partner should tape the paper on the wall where the pattern appears. Then he or she should take a minute to memorize the colors int he spectrum and how they're arranged.

When your partner is ready to draw, turn the lights back on. After he or she has finished drawing, turn the lights off again and check the pattern and colors. Do this a few times to make sure the drawing of the spectrum matches what you see on the wall.

Shining Light through an Audiocassette Case Containing Water

You'll be using only the top part of the case (that is, the part the cassette slides into). Remove all parts of the label on the case. Hold the case upright, so that the small enclosed part is at the bottom, and carefully add water until it's almost filled.

Darken the room again.

Your partner should once again be ready to tape a piece of white paper on the wall where the spectrum appears.

Pick up the audiocassette case and move it near the wall. Turn on the flashlight and hold it near the case, aiming the light into the water. As you did earlier, move the flashlight up and down, back and forth,a dn over and under the container until you see a spectrum somewhere on the wall or floor. It will be a small patch of colors. (Hint: Be sure to look in back of you as you search!)

When you find the spectrum, give your partner a little time to study and memorize it. Then turn the lights back on, and have him or her draw the pattern using the colored markers or crayons. Turn off the lights and check the spectrum a few times to make sure the drawing matches the pattern on the wall.

3. Think and Write

Study the drawings of the spectrums. In a short paragraph, describe how you could use what you learned in this activity to invent a way of making white light by putting the colors back together. Imagine that you have as much equipment as you need! Make a labeled drawing to show how your idea would work.

Explanation

White light is actually a mixture of many different colors, but they aren't visible until the light is broken up. You can do this with a triangular piece of glass called a prism or any clear container of water. The light that leaves the prism or water forms a pattern of colors called a spectrum.