Question

Draw a labelled diagram to explain the formation of rainbow in the sky.

Answer 1

The formation of a rainbow involves a series of physical phenomena - reflection, refraction, dispersion and total internal reflection.  The occurence of each of these is due to the interaction of light with air and water and the boundaries between them.   As light enters the raindrop, it is refracted (the path of the light is bent to a different angle), and some of the light is reflected by the internal, curved, mirror-like surface of the raindrop, and finally isrefracted back out the raindrop toward the observer.

Conditions necessary to observe a rainbow: (1) The Sun should be behind us. (2) It should have rained and the Sun should be present.