Two polarisers P₁ and P₂ are placed in such a way that the intensity of the transmitted light will be zero. A third polariser P₃ is inserted in between P₁ and P₂, at particular angle between P₂ and P₃. The transmitted intensity of the light passing through all three polarisers is maximum. The angle between the polarisers P₂ and P₃ is: (a) π/6 (b) π/3 (c) π/4 (d) π/8

Answer: (c). Zero output means P₁ and P₂ are crossed. With P₃ at θ to P₁: I = I₀/8sin ² 2θ Maximum when sin 2θ = 1, θ = 45°, so P₃ is also at 90° - 45° = 45° to P₂. So the answer is (c) π/4.

Two polarisers P₁ and P₂ are placed in such a way that the intensity… | JEE Main 2025 (4 Apr, Shift 2)

Q22JEE Main 2025 · 4 APR · SHIFT 2Medium

Polarisation

Two polarisers $P_1$ and $P_2$ are placed in such a way that the intensity of the transmitted light will be zero. A third polariser $P_3$ is inserted in between $P_1$ and $P_2$ , at particular angle between $P_2$ and $P_3$ . The transmitted intensity of the light passing through all three polarisers is maximum. The angle between the polarisers $P_2$ and $P_3$ is:

Show answer and solution

Answer: (c)

Zero output means $P_1$ and $P_2$ are crossed. With $P_3$ at $\theta$ to $P_1$ : $I = \frac{I_0}{8}\sin^2 2\theta$
Maximum when $\sin 2\theta = 1$ , $\theta = 45^\circ$ , so $P_3$ is also at $90^\circ - 45^\circ = 45^\circ$ to $P_2$ .
So the answer is (c) $\frac{\pi}{4}$ .

Report a mistake

Polarisation question from JEE Main 2025 (4 Apr, Shift 2)

More questions on Polarisation