Question

What should be the minimum value of refractive index of the material of the prism for the reflections to take place as shown in the figure :

• A. 1.7
• B. 1.4
• C. 1.2
• D. 2.7

Answer 1

Answer: (B)

From the formula, the minimum refractive index is
$\mu_{m}=\frac{\sin i}{\sin r}=\frac{\sin 90^{\circ}}{\sin 45^{\circ}}$
$=\frac{1}{1 / \sqrt{2}} =\sqrt{2}=1.414=1.4$