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

When the white light splits into seven color on passing through a transparent medium like a glass prism is called dispersion of light.

The formation of a rainbow can be shown in the fig. given bellow:-

Like the prism acts the rainbow. During the rain when sunlight enters and leaves these raindrops, the various colored rays in white light are refracted by different amounts due to which an arc of seven colors called rainbow is formed.