Question

A light ray goes from a medium of refractive index$\sqrt{2}$ to a medium of refractive index 1. The minimum angle of incidence for TIR to happen is .

• A. ${30}^{\circ }$
• B. ${45}^{\circ }$
• C. ${60}^{\circ }$
• D. ${90}^{\circ }$

Answer 1

The correct option is B ${45}^{\circ }$

Critical angle = $si{n}^{-}\left(\frac{{\mu }_r}{{\mu }_i}\right)=si{n}^{-}\frac{1}{\sqrt{2}}={45}^{\circ }$