Topic: Polarization, Brewster's law, Polaroids· Optics

An unpolarized light beam travelling in air is incident on a medium of refractive index 1.73 at Brewster's angle. Then-

1. reflected light is completely polarized and the angle of reflection is close to $60^\circ$

2. reflected light is partially polarized and the angle of reflection is close to $30^\circ$

3. both reflected and transmitted light are perfectly polarized with angles of reflection and refraction close to $60^\circ$ and $30^\circ$, respectively.

4. transmitted light is completely polarized with angle of refraction close to $30^\circ$

Doubtly Asked 30 Oct 2026 NEET UG 2025 Practice test neet Save WhatsApp Report

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Answer: 1. reflected light is completely polarized and the angle of reflection is close to $60^\circ$

Key idea: at Brewster's angle $\tan i_B=\mu$, and the reflected light is completely plane polarized.

$$\tan i_B=1.73=\sqrt3\Rightarrow i_B=60^\circ$$

The angle of reflection equals the angle of incidence, so it is $60^\circ$ and the reflected light is completely polarized. The refracted ray is only partially polarized (angle $30^\circ$), so options 2, 3 and 4 are wrong.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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An unpolarized light beam travelling in air is incident on a medium of refractive index 1.73 at Brewster's angle. Then-

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