Wave Optics: NEET and JEE questions with solutions

Answer: (A) reflected light is completely polarized and the angle of reflection is close to $60°$

Brewster's law: $\tan i_B = n = 1.73 \approx \sqrt{3}$, so $i_B = 60°$. The angle of reflection equals the angle of incidence, $60°$.

At Brewster's angle the reflected light is completely (plane) polarized, while the transmitted light is only partially polarized. The angle of refraction is $90° - 60° = 30°$, but the transmitted light is not completely polarized.

So the correct statement is (1).

Solution by Sreeraj P, M.Sc Physics

Answer: (C) $\dfrac{I_0}{8}$

The middle sheet is at $22.5°$ to the first polaroid, so it is at $90° - 22.5° = 67.5°$ to the second (crossed) polaroid. By Malus's law:
$$I = I_0\cos^2 22.5°\cos^2 67.5° = I_0(\cos 22.5°\sin 22.5°)^2 = I_0\left(\frac{\sin 45°}{2}\right)^2 = I_0 \times \frac{1}{8}$$

Solution by Sreeraj P, M.Sc Physics