Question

The velocity of light in water is $2.25\times {10}^{8}m{s}^{-1}$. A ray of light travelling in air is incident on an air water interface at angle of incidence of ${30}^0$. Calculate the angle of refraction. Find also the angle of deviation.

Answer 1

$\mu =\frac{\text{velocity of light in air}}{\text{velocity of light in another medium}}$

$\mu =\frac{3\times {10}^8}{2.25\times {10}^8}=\frac{3}{2.25}$

$\begin{array}{c}\text{According to snell's law}\\ \begin{array}{cc}\mu =& \frac{\sin i}{\sin r}i={30}^{\circ }\text{given}\\ \frac{3}{2.25}=& \frac{\sin {30}^{\circ }}{\sin r}\\ \sin r& =\frac{1}{2}\times \frac{2.25}{3}\\ \sin r& =0.375\\ r& ={\sin }^{-1}\left(0.375\right)\end{array}\end{array}$

$={22.0243}^o$