Question

A ray of light travelling in a transparent medium of refractive index , falls on a surface separating the medium from air at an angle of incidence of ${45}^o$. For which of the following value of refractive index the ray can undergo total internal reflection :

• A. 1.33
• B. 1.4
• C. 1.5
• D. 1.25

Answer 1

Answer: (C)

1.5

For total internal reflection: $\mu \ge \frac{1}{\sin i}\mu \ge \frac{1}{\sin {45}^{\circ }}\mu \ge \sqrt{2}\mu \ge 1.4142$

Hence option 'C' is correct.