Rainbows and Water - a Sun Project
Quatr.us answers questions

Sun Project

Sun in sky

You can see that the sunlight that reaches the Earth travels at different wavelengths. On a sunny day, put a full glass of water (a real glass glass) in the sunshine on your windowsill. Look where the sunshine goes through the water, and you should see rainbows on the floor or walls.

Those rainbows happen when the water bends the waves of sunlight going through it. The light coming from the sun looks white because it is a mixture of all wavelengths of light. When the light goes through the water, the shorter wavelengths get bent more than the longer wavelengths do, so you end up with the short wavelengths hitting the wall at a different place from the longer wavelengths: that's what makes a rainbow.

Do you think this would work with moonlight? Why or why not? How about light from a light bulb? What about firelight? Try it and see!

More about the Sun

Bibliography and further reading about the sun:

The Earth
The Moon
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Professor Carr

Karen Eva Carr, PhD.
Assoc. Professor Emerita, History
Portland State University

Professor Carr holds a B.A. with high honors from Cornell University in classics and archaeology, and her M.A. and PhD. from the University of Michigan in Classical Art and Archaeology. She has excavated in Scotland, Cyprus, Greece, Israel, and Tunisia, and she has been teaching history to university students for a very long time.

Professor Carr's PSU page

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