Question

Angle of minimum deviation for a prism of refractive index 1.5 is equal to the angle of prism. The angle of prism is $\left( \cos 41 ^ { \circ } = 0.75 \right)$

• A. 62⁰
• B. 41⁰
• C. 82⁰
• D. 31⁰

Answer 1

Answer: (C)

82⁰

Answer 2

Given $\Rightarrow \mu = \frac { \sin \frac { A + A } { 2 } } { \sin \frac { A } { 2 } }$ $\left\{ \sin A = 2 \sin \frac { A } { 2 } \cos \frac { A } { 2 } \right\}$

$\Rightarrow$ $1.5 = 2 \cos \frac { A } { 2 } \Rightarrow 0.75 = \cos \frac { A } { 2 } \Rightarrow 41 ^ { \circ } = \frac { A } { 2 } \Rightarrow A = 82 ^ { \circ }$