Question

A prism has a refracting angle $60^{\circ }$. A ray of given monochromatic light suffers minimum deviation of $38^{\circ }$ in passing through prism refractive index of the material of prism is :

• A. 1.5094
• B. 1.3056
• C. 0.7849
• D. 2.425

Answer 1

Answer: (A)

Here : Refracting angle $A=60^{\circ }$ minimum deviation $\delta m=38^{\circ }.$
The refractive index is given by the formula
$\mu =\frac{\sin \frac{A+\delta m}{2}}{\sin \frac{A}{2}}=\frac{\sin \frac{60^{\circ }+38^{\circ }}{2}}{\sin \frac{60^{\circ }}{2}}$
$=\frac{\sin 49^{\circ }}{\sin 30^{\circ }}=\frac{0.7547}{0.5}=1.5094$