Question

A ray light strikes a transparent rectangular slab of refractive index $\sqrt { 2 }$ at an angle of incidence of 45⁰. The angle between the reflected and refracted rays is :

• A. 75⁰
• B. 90⁰
• C. 105⁰
• D. 120⁰

Answer 1

Answer: (C)

105⁰

Answer 2

: Here, $\mathrm { i } = 45 ^ { \circ }$

Applying snell’s law at air – glass surface, we get

$= \frac { 1 } { \sqrt { 2 } } \sin 45 ^ { \circ }$

$r ^ { \prime } = \sin ^ { - 1 } \left( \frac { 1 } { 2 } \right) = 30 ^ { \circ }$

From figure,

$45 ^ { \circ } + \theta + 30 ^ { \circ } = 180 ^ { \circ }$

$\theta = 180 ^ { \circ } - 75 ^ { \circ } = 105 ^ { \circ }$

Hence, the angle between reflected and refracted rays is $105 ^ { \circ }$