When unpolarized light is incident at an angle of 60° on a transparent medium from air. The reflected ray is completely polarized. The angle of refraction in the medium is

We need to find the angle of refraction when unpolarised light is reflected with complete polarisation.

Key Concept: Brewster's Law

When unpolarised light strikes a surface at the Brewster angle ($$i_B$$), the reflected light is completely polarised. At this angle:

$$\tan i_B = \mu$$

Also, at Brewster's angle, the reflected and refracted rays are perpendicular:

$$i_B + r = 90°$$

Angle of incidence = 60° (this is the Brewster angle).

Finding the angle of refraction:

$$r = 90° - i_B = 90° - 60° = 30°$$

Verification: $$\tan 60° = \sqrt{3} = \mu$$. By Snell's law: $$\sin 60° = \sqrt{3} \sin r$$, so $$\sin r = \frac{\sqrt{3}/2}{\sqrt{3}} = \frac{1}{2}$$, giving $$r = 30°$$. ✓

The correct answer is Option 1: 30°.