A light ray is incident on the lower medium boundary at an angle `30^(@)` with the normal. Which of the following statements is true?

Options

A. If `mu_(2) gt 2` then total deviation is `60^(@)`
B. If `mu_(2) lt 2` then total deviation is `60^(@)`
C. If `mu_(2) gt 2` then total deviation is `120^(@)`
D. If `mu_(2) lt 2` then total deviation is `120^(@)`

Answer

A, D

Explanation

For refraction `mu_(1) sin 30^(@) = mu_(2) sin theta = mu_(3) sin e`
`rArr 2 = mu_(2) sin theta = 2 sin e`
For emergence through B
`sin theta lt 1`
`2 lt mu_(2), e= 90^(@)`
`D = 90^(@) - 30^(@) = 60^(@)`
If `mu_(2) lt 2` ray will suffer TlR on A
`D = 180^(@) -2 xx 30^(@) = 120^(@)`.