Question

The refractive index of glass with respect to air is $2$. Then the critical angle of glass-air interface is ______

• A. $0^{\circ }$
• B. ${45}^{\circ }$
• C. ${30}^{\circ }$
• D. ${60}^{\circ }$

Answer 1

The correct option is C ${30}^{\circ }$

We know that the critical angle is given by:-

$C={\sin }^{-1}\frac{1}{\mu }$ where $\mu$=refractive index of denser medium relative to rarer medium

Here, $\mu =2$

Hence, $C={\sin }^{-1}\frac{1}{2}$

$⟹C={30}^o$

Answer-(C)