Question

The figure given below shows a container C partially filled with water. There is a plane mirror M at the bottom of the container. A light ray AB incidents on the surface of water at angle of incidence ${30}^{\circ }$. Copy and complete the ray diagram. Mark the ray emerging from the water surface. Refractive index of water = $\frac{4}{3}$.

Answer 1

The ray is incident at angle $\angle i={60}^0$

By snell's law

$\mu =\frac{sini}{sinr}\frac{4}{3}=\frac{sin{60}^0}{sinr}\Rightarrow r={41}^0$

The refracted ray goes to surface QR and strikes to the mirror and reflects at the same angle $r={41}^0$

and then reflects ray from mirror travels upward and refract at surface PS

the refracted angle is calculated using snell's law

$\frac{1}{\mu }=\frac{sin{41}^0}{sine}\frac{3}{4}=\frac{sin{41}^0}{sine}\Rightarrow e={60}^0$