Rainbow is mainly caused when light hits the tinu raindrops and reflects from the surface of those drops. The raindops actually works as a prism by separating the different bands of light that are present within the white sunlight. We continuously see the raindrops because one drop of rain is quickly replaced by another and this causes a continuous effect. The angle between the incoming light and the reflected light is 4o degrees for violet band and 42 degrees for the red band. The angle of bending is always different for different colors of light.
