Question

If the angle of a prism is 60${}^{\circ }$ and angle of minimum deviation is 40${}^{\circ }$, then the angle of refraction in the prism will be

• A. 30${}^{\circ }$
• B. 45${}^{\circ }$
• C. 50${}^{\circ }$
• D. 20${}^{\circ }$

Answer 1

The correct option is A 30${}^{\circ }$

for minimum deviation

$r=r^1$

given A=60

$r+r^1=A$

2r = A$\Rightarrow$ r=$\frac{A}{2}$

r =${30}^0$

Hence, the angle of refraction will be, $r=\frac{A}{2}$ = ${30}^o$