Rainbow — Prelims Questions

Which of the following phenomena is NOT involved in the formation of a primary rainbow?

A primary rainbow has an angular radius of approximately $42^\circ$. If the refractive index of water for red light is $n_R = 1.33$ and for violet light is $n_V = 1.34$, which color will appear on the outer edge of the primary rainbow?

A secondary rainbow is observed. What is the approximate angular radius of the secondary rainbow, and what is the order of colors from top to bottom?

An observer sees a rainbow. If the sun is in the west, in which direction should the observer look to see the rainbow?

The critical angle for water-air interface is approximately $48.75^\circ$. If a light ray inside a raindrop strikes the back surface at an angle of incidence of $45^\circ$, what will happen to the light ray?

Why is the sky between the primary and secondary rainbows often observed to be darker than the sky inside the primary rainbow or outside the secondary rainbow? This dark band is known as 'Alexander's Dark Band'.