Question

Find the angle of refraction for a ray of light travelling from glass to air. Given angle of incidence is ${30}^{\circ }$ and refractive index of glass is ${\mu }_g=\sqrt{2}$.

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

Answer 1

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

Given:
Angle of incidence, $i={30}^o$
Refractive index of glass, ${\mu }_g=\sqrt{2}$

Let angle of refraction be $r$.

Applying Snell's law :
$\frac{\sin i}{\sin r}=\frac{{\mu }_a}{{\mu }_g}$
$\frac{\sin \left({30}^{\circ }\right)}{\sin r}=\frac{1}{\sqrt{2}}$
$\sin r=\sqrt{2}\times \frac{1}{2}$
$\sin r=\frac{1}{\sqrt{2}}$
$⟹r={45}^{\circ }$