Question

How prism produces spectrum .and what happen if water droplet is circular in rainbow formation

Answer 1

This causes light of different colors to be refracted differently and to leave the prism at different angles, creating an effect similar to a rainbow. This can be used to separate a beam of white light into its constituent spectrum of colors. A water droplet refracts and disperses the incident sunlight, then reflect it internally and finally refract it again, when it emerges out of water droplet thus acting like a prism.