Question

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

• A. 30°
• B. 60°
• C. 90°
• D. 45°

Answer 1

The Correct Option is A

According to Brewster’s law, the reflected ray is completely polarized when the angle of incidence \( \theta_p \) satisfies:

\[ \tan \theta_p = n, \]

where \( n \) is the refractive index of the medium relative to air.

Given \( \theta_p = 60^\circ \), we have:

\[ n = \tan 60^\circ = \sqrt{3}. \]

Using Snell’s law \( n_1 \sin \theta_1 = n_2 \sin \theta_2 \), with \( n_1 = 1 \) (for air) and \( \theta_1 = 60^\circ \):

\[ \sin \theta_2 = \frac{\sin 60^\circ}{\sqrt{3}} = \frac{\sqrt{3}/2}{\sqrt{3}} = \frac{1}{2}. \]

Therefore, \( \theta_2 = 30^\circ \).