Rainbow consist of how many colours?
A rainbow usually consists of seven colors: red, orange, yellow, green, blue, indigo, and violet. Rainbows are an optical phenomenon caused by the refraction and dispersion of light through water droplets in the atmosphere. The seven colors of a rainbow are arranged in the order of the spectrum of visible light, and each color has its own wavelength. Rainbows can appear in the form of a full circle, a semi-circle, or as an arc. They are most often seen after a rainstorm, when the sun is shining and the sky is clear.