`P` is small angled prism of angle `3^(@)` made of a material of refractive index `1.5`. A ray of light is incident normally to the mirror as shown in figure. `M` is a plane mirror. The angle of deviation for the ray reflected from the mirror `M` with respect to the incident ray is :

Options

A. `4.5^@`
B. `175.30^@`
C. `177^@`
D. `178.5^@`

Answer

D

Explanation

Deviation by prism `delta=(mu-1)A=(1.5-1)(3)=1.5^@`

`delta=180-1.5=178.5^@`
OR
Deviation by prism `=1.5^@`
Deviation by mirror `=180^@-2xx1.5^@=177^@`
Total deviation `=1.5^@+177^@=178.5^@`