Three polarised sheets are co-axially placed. Pass axis of polaroids 2 and 3 make 30° and 90° with pass axis of polaroid sheet 1. If I₀ is the intensity of unpolarised light entering sheet 1, the intensity of the emergent light through sheet 3 is (cos 30° = √(3)/2, cos 90° = 0, cos 60° = 1/2) (a) zero (b) (3I₀)/(32) (c) 3I₀/8 (d) (3I₀)/(16)

Answer: (b). After sheet 1: I₀/2. Sheet 2 at 30°: I₀/2cos ² 30° = 3I₀/8 Sheet 3 at 60° to sheet 2: 3I₀/8cos ² 60° = (3I₀)/(32) So the answer is (b) (3I₀)/(32).

Three polarised sheets are co-axially placed. Pass axis of polaroids… | MHT CET 2025 (21 Apr, Shift 1)

Q19MHT CET 2025 · 21 APR · SHIFT 1Medium

Polarisation

Three polarised sheets are co-axially placed. Pass axis of polaroids 2 and 3 make $30^\circ$ and $90^\circ$ with pass axis of polaroid sheet 1. If $I_0$ is the intensity of unpolarised light entering sheet 1, the intensity of the emergent light through sheet 3 is

$\left(\cos 30^\circ = \sqrt{3}/2, \cos 90^\circ = 0, \cos 60^\circ = 1/2\right)$

Show answer and solution

Answer: (b)

After sheet 1: $I_0/2$ .
Sheet 2 at $30^\circ$ : $\frac{I_0}{2}\cos^2 30^\circ = \frac{3I_0}{8}$
Sheet 3 at $60^\circ$ to sheet 2: $\frac{3I_0}{8}\cos^2 60^\circ = \frac{3I_0}{32}$
So the answer is (b) $\frac{3I_0}{32}$ .

Report a mistake

Polarisation question from MHT CET 2025 (21 Apr, Shift 1)

More questions on Polarisation