A right-angled prism of apex angle `4^(@)` and refractive index 1.5 is located in front of a vertical plane mirror as shown in figure. A horizontal ray of light is falling on the prism. Find the total deviation produced in the light ray as it emerges 2nd time from the prism.

Options

A. `8^(@)CW`
B. `6^(@)CW`
C. `180^(@)CW`
D. `174^(@)CW`

Answer

d.

Explanation

Deviation produced by prism is
`delta_(1)=(mu-1)A=2^(@)CW`
Angle of incidence for mirror is `delta_(1)`, so deviation produced by the mirror is
`delta_(2)=pi-2delta_(1)=176^(@)CW`
Deviation produced by the prism for `2^(nd)` refraction is
`delta_(3)=2^(@)ACW`
Net deviation `=174^(@)CW`