What is meant by dispersion of white light ? Describe the formation of rainbow in the sky with the help of a diagram.

Explanation

The rainbow is produced due to the dispersion of sunlight by tiny droplets of water suspended in air, just after rain. From the figure when the sunlight is incident on the side A of the droplet of water, it gets refracted as well dispersed. The dispersed rays on striking the surface B of tiny droplets, suffer total internal reflection and moves towards surface A, the rays further suffer refraction and emerge out as the band of colours in the form of a circular arc (rainbow) along the horizon. The red colour appears upper arc and violet colour on the innermost arc of the rainbow.