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For the first rainbow, you'll need a glass, some water, a sunny room or a bright flashlight and a piece of white paper. This is a good experiment to do with another person, as extra hands are helpful. Hold the glass above the paper so that the sun is shining through the water or have a friend hold the flashlight so that it is shining into the water.
Slowly and carefully move the glass around until you begin to see colors in the light shining through the water. You might want to try this in a darkened room. Experiment with tilting the glass, changing the angle of the light, etc. What works the best?
The second rainbow experiment requires a shallow pan, a mirror, a flashlight, water and a white piece of paper. Pour some water into the pan about halfway. Place the mirror so that it is leaning on the edge of the pan, partially in the water. (You might find it is helpful to put a piece of tape on your mirror to hold it in place)
Shine the flashlight at the part of the mirror that is under the water. Have a friend hold the white paper above the pan. Make adjustments until you begin to see the colors of the rainbow on the paper.
# 3-We've probably all experimented with making rainbows with a hose in the summer time. It might not be the best weather to head outside and turn on the hose, but you can recreate this effect on a sunny day inside. Choose a sunny window and spritz some water from a spray bottle onto it. What do you notice?
|Prism by D-Kuru Wikimedia Commons|
If you have a prism, or even if you don't, you can make a 4th rainbow. A prism is a transparent geometric shape that refracts light. They may be made of glass or plastic. You probably have something in your house that will work as a prism. We have a door with some beveled glass that makes rainbows in our living room when it is sunny. What do you have in your house that might work like a prism?
Lastly, you can use the underside of a cd and a flashlight to make a rainbow. You probably can already see the different colors in the cd as you move it in the light. What happens when you shine the flashlight on the cd? How does moving the flashlight change the colors that you can see?
So how does a rainbow work anyway? Rainbows occur when raindrops or moisture in the air refract, or bend, the white light of the sun. Although we consider it "white light", light is made up of many colors. When light bends, as it does when it bounces off a prism or a water droplet, all of the colored light that makes up the white light bends too. When white light bends you see specific colors within the light. These colors are Red, Orange, Yellow, Green, Blue, Indigo and Violet, or ROY G. BIV.
Here is one way to remember the colors of the rainbow:
For more videos that teach science in a fun way like this, check out my post "10 Tried and True Videos for Teaching Science"
Check out more fun science songs on They Might Be Giants- Here Comes Science album and DVD.
Here's a St. Patrick's Day science bonus for you- "How Science Can Help You Find a Four Leaf Clover" from Scientific American
Have fun experimenting!