Science Buddies: "Ask an Expert"

I need an experiment proceedure to prove that the colors of a rainbow can not change the order they appear in.

Hi ksenor,

A good description of the rationale for the order of colors of a rainbow is at:
http://www.enotes.com/science-fact-find ... rs-rainbow

Here, you'll discover that the order of the colors is based on the frequency of the light. The mnemonic for remembering the order is ROY G. BIV (red, orange, yellow, green, blue, indigo, violet).

The only experiment that I can think of is to develop a multi-colored light, pass it through water and see the order of colors produced by its "rainbow."

One could I suppose:
1. filter a color out of white light and look at its "rainbow." This may be uninteresting, because the expected result is a normal rainbow, less the filtered color.
2. develop light with only two colors and see if the order of its "rainbow" is the same as the order in a normal rainbow: ROY G. BIV (red, orange, yellow, green, blue, indigo, violet). This is probably what you were looking for. I'm not sure exactly how to achieve two colored light, except using two lasers or five filters applied to normal white light. I don't know if either of these two are practical.

Maybe others can help.

Hi ksenor,

Dave gave you some good information. The colors of the rainbow are organized based on their frequency (which is inversely proportional to wavelength), and each color is associated with a characteristic frequency, which doesn't change.

You should definitely do a bit of background research on optics. I think that you could do an experiment using different prisms. A prism is a device that refracts light and causes it to separate into its component colors. Here is a link to Wikipedia's article about prisms: http://en.wikipedia.org/wiki/Prism_(optics)

I like Dave's idea of using different source colors and/or filtered light, and seeing whether the order still holds. If you combine this idea with the use of prisms, you will have a very interesting and fun experiment!

Good luck!
Heather