Question

A ray of light traveling in a transparent medium falls on a surface separating the medium from air, at an angle of ${45}^{\circ }$. The ray undergoes total internal reflection. if 'n' is the refractive index of the medium with respect to air, select the possible values of 'n' from the following.

• A. 1.3
• B. 1.4
• C. 1.5
• D. 1.6

Answer 1

Answer: (C), (D)

The correct options are
C 1.5
D 1.6

The angle of incidence of all the rays is ${45}^{\circ }$ at the hypotenuse. For a critical angle of ${45}^{\circ }$, the refractive index must be
${\left(\sin {45}^{\circ }\right)}^{-1}=\sqrt{2}=1.414$