A ray of light travelling from glass to air is incident at `50^(@)` from the glass air boundary . What is the angle of deviation if the critical angle is `42^(@)` ?

Options

A. `0^(@)`
B. `60^(@)`
C. `80^(@)`
D. `sin^(-1) [ (sin 50^(@))/(1.5)] - 50`

Answer

C

Explanation

`because igt c ( 50^(@) gt 42^(@)`)
The ray suffers total internal reflection . The glass air boundary acts as a plane mirror and deviation produced by plane mirror , when the ray is incident at an angle `i` is `delta = 180^(@) - 2i = 180^(@) - 100^(@) = 80^(@)`