Question

The angle of a prism is 30${}^{\circ }$. The rays incident at 60${}^{\circ }$ at one refracting face suffer a deviation of 30${}^{\circ }$. The angle of emergence is

• A. 0${}^{\circ }$
• B. 30${}^{\circ }$
• C. 60${}^{\circ }$
• D. 90${}^{\circ }$

Answer 1

The correct option is A 0${}^{\circ }$

Angle of prism is $A={30}^o$,

Angle of incidence is $i={60}^o$,

Deviation is $\delta ={30}^o$,

Let angle of emergence be $e$ ,

For prism relation between them is given by ,

$\delta +A=i+e$,

putting the values we get,

$30+30=e+60$

$\therefore e=0$

Angle of emergence is $0$.