A ray of light is incident normally on one of the faces of a prism of apex angle 30° and refractive index $\sqrt{2}$. The angle of deviation of the ray is
Answer & explanation
Correct answer: option 1
Besides the formulae given for prism, we can always use the basic laws of refraction.
Using Snell’s law for the refraction at AC, we obtain
$\frac{\sin i}{\sin r}=\frac{n_2}{n_1}$
$⇒\frac{\sin 30°}{\sin r}=\frac{1}{\sqrt{2}}$
$⇒\sin r=1/\sqrt{2}$
⇒ r = 45°.
The angle of deviation, D = 45° - 30° = 15°