Question

If angle of minimum deviation by an equilateral prism is equal to its prism angle, then the refractive index of material of prism can be

• A. $1.12$
• B. $1.73$
• C. $1.40$
• D. $1.08$

Answer 1

The correct option is B $1.73$

We have,
Refractive index of prism $n=\frac{\sin \left(\frac{A+{\delta }_{min}}{2}\right)}{\sin \left(\frac{A}{2}\right)}$ $(A={\delta }_{min}=60°)$

$n=\frac{\sin {60}^{\circ }}{\sin {30}^{\circ }}$
$n=\sqrt{3}$
$n=1.73$