Question

If a light ray from air enters three different media in such a way that the refracted angles are ${45}^0$, ${30}^0$ and ${60}^0$ respectively. Identify the right statement with respect to the optical density of these media.

• A. Optical density is highest for medium 3.
• B. Optical density is least for medium 2.
• C. Optical density is least for medium 3.
• D. Optical density is highest for medium 2.

Answer 1

The correct option is D

Optical density is highest for medium 2.

Angle of incidence $i$ is same for all three media. Angle of refraction for the different media are:
$r_{m1}={45}^{\circ }$
$r_{m2}={30}^{\circ }$
$r_{m3}={60}^{\circ }$

Deviation will be highest for medium with highest optical density. Clearly, the deviation is highest $\left({30}^{\circ }\right)$ for Medium 2. Hence, Medium 2 has highest optical density.