Question

Refractive index of water and glass are $4 / 3 \& 3 / 2$ respectively. A ray of light travelling in water is incident on the water glass interface at $30^{\circ} .$ Calculate the angle of refraction.

• A. $30^{\circ}$
• B. $25^{\circ}$
• C. $26.38^{0}$
• D. $27^{0}$

Answer 1

Answer: (C)

$^{a} \mu_{w}=\frac{4}{3},^{a} \mu_{g}=\frac{3}{2}$
${ }^{w} \mu_{g}=\frac{{ }^{a} \mu_{g}}{{ }^{a} \mu_{w}}=\frac{\frac{3}{2}}{4 / 3}=\frac{9}{8}$
$\frac{\sin i}{\sin r}={ }^{w} \mu_{g}=\frac{9}{8}$
$\sin r=\frac{8}{9} \times \frac{1}{2}$
$\sin r=\frac{4}{9}$
$r=26.38^{0}$