The Brainliest Answer!
Rainbow is an example of the dispersion of sunlight by the water drops in the atmosphere
a) primary rainbow
In primary rainbow, after refraction at the surface of water droplet, the ray suffers one internal reflection & 2 refraction
b) secondary rainbow
In secondary rainbow the ray suffers 2 total internal reflection & 2 refraction.
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Oh i m so sorry i was not knowing coz i m new 
i hav just started 2 days before
It's ok!! But dont repeat ^_^