Why does a rainbow consists of 7 colors?
Visible light is made up of light of many wavelengths, from about 400 nanometres to about 700 nanometres. A rainbow acts as a prism, splitting light into its component colours. We normally number seven colours in a rainbow, but of course, as you look at a rainbow, you see each colour shading into the next, so there are hundreds or thousands of colours in a rainbow.
