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)

1.4

Answer 2

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