A ray of light incident at an angle `theta` on a refracting face of a prism emerges from the other face normally. If the angle of the prism is `5^@` and the prism is made of a material of refractive index `1.5`, the angle of incidence is.

Options

A. `7.5^(@)`
B. `5^(@)`
C. `15^(@)`
D. `2.5^(@)`

Answer

1

Explanation

Since, deviation `delta = (mu - 1)A`
= (1.5-1)`xx5^(@) = 2.5^(@)`
The angle ofthe prism is `5^(@)` .The ray emerges from refracting face of a prism normally.
Then , `i_(2)=r_(2)=0`
As A=`r_(1)+r_(2) implies r_(1)=A` or `r_(1)=5^(@)`
But `i_(1) =mu*r_(1)=3/2 xx 5 =7.5^(@)`