Question

An equilateral prism deviates a ray through $45^\circ $ for two angles of incidence differing by $20^\circ $ . The angles of incidence are :

• A. $60^\circ $ and $40^\circ $
• B. $50^\circ $ and $70^\circ $
• C. $62^\circ 30'$ and $42^\circ 30'$
• D. $60^\circ 30'$ and $40^\circ 30'$

Answer 1

Answer: (C)

$\delta = \text{i}_{1} + \text{i}_{2} - \text{A}$
$4 5^{^\circ } = \text{i}_{1} + \text{i}_{2} - 6 0^{^\circ }$
$\text{i}_{1} + \text{i}_{2} = 1 0 5^{^\circ }$
$\text{i}_{1} - \text{i}_{2} = 2 0^{^\circ }$
or $2 \text{i}_{\text{i}} = 1 2 5^{^\circ }$
$\text{i}_{1} = 6 2^{^\circ } 3 0^{'} \text{, } \text{i}_{2} = 4 2^{^\circ } 3 0^{'}$