|MadSci Network: Physics|
The colors that we attribute to a rainbow (red, orange, yellow, green, blue, indigo, violet) are arbitrary! In actual fact, the light from the sun, and the light that we see in a rainbow, is a CONTINUOUS spectrum of light frequencies. We pick out six or seven significant colors that we see and say that the rainbow is made of those colors. But all the frequencies (colors) are actually there, so when "white" light from the sun reflects from an object there is no dearth of frequencies available to get to our eyes to make up other perceived colors.
There are some answers already on our site which deal with the mixing of colors, which you can find by using our search engine at http://www.madsci.org/ MS_search.html.
John Link, MadSci Physicist
Try the links in the MadSci Library for more information on Physics.