A point source is placed at a depth h below the surface of water (refractive index = mu). (a) Show that light escapes through a circular area on the water surface with its centre directly above the point source. (b) Find the angle subtended by a radius of the area on the source.

Answer

A, B

Explanation

a. Let P is a point source placed at a depth h.
Clearly from ure the light escapes at a fixed distance r at water surface.
that madks a critical whose centre is just above P.

`rarr sintheta=1/mu`
`rarr v=sin^-1(1/mu)`