A passenger in an aeroplane shall

Options

A. never see a rainbow
B. may see a primary and a secondary rainbow as concentric circles.
C. may see a primary and a secondary rainbow as concentric arcs.
D. shall never see a secondary rainbow.

Answer

B

Explanation

Rainbows are formed due to dispersion of light. Sunlight enters the front of a raindrop.It hits the back side of the drop, reflects and then head back out of the front side again. The sunlight bends a little bit when it enters and exits the drop and different colours bend by different amounts. The total deviation observed is approximately `138^(@)` (red light bends a little less and blue light a little more).
To see a rainbow, we generally face away from the Sun `(180^(@))` and then look about `42^(@)` away `(180^(@) -138^(@))`. The drops in an arc along that angle will then bend the light back towards you and you see a rainbow. We generally see rainbows in sky because the ground is closer to us and when we look up towards the sky we see for a long way, and there are lots of raindrops along your eyeline. When we look down, the ground becomes a barrier and there aren.t as many raindrops. It is possible to look down and see a rainbow while you are in an aeroplane and when it.s raining. If the Sun is at the right location and you look out the opposite side, you will be able to see a rainbow making a full circle. This is because every raindrop in the air that is `42^(@)` away from the spot in the sky opposite the Sun can bend the light back towards you. All those raindrops are at the same distance from that point and that defines the edge of circle.
Correct option is (b).