Explain the formation of a rainbow.

Explanation

1) Rainbow : The rainbow is an arch of seven colours visible in the sky which is produced by the dispersion of sun's light by raindrops in the atmosphere.
2) Observe the figure. The rays of sunlight enter the drop near its top surface.
3) At this first refraction, the white light is dispersed into its spectrum of colours , violet being deviated the most and red the least.
4) Reaching the opposite side of the drop, each colour reflected back into the drop because of total internal reflection.
5) Arriving at the surface of the drop , each colour is again refracted into air.When compared to the angle between those at first refraction.
7) We observe bright rainbow when the angle between incoming and outgoing rays is near maximum angle of `42^(@)`
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