Explain how formation of rainbow occurs. Ans.

1. The rainbow appears in the sky during a rain shower.
   
2. The water droplets act as small prisms. When sunlight enters the water droplets present in the atmosphere, they refract and disperse the
   incident sunlight.
   
3. Then they reflect it internally inside the droplet and finally again refract
   it. As a collective effect of all these phenomenon, the seven coloured
   rainbow is observed.