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CUET · PHYSICS · PYQ PAPER 2023

An unpolarised light of intensity \( I_0 \) passes through five identical polarisers arranged in such a manner that the transmission axis of each is set at an angle of 30° with respect to its predecessor. The ratio of the intensity of the final emerging light to that of the unpolarised light is

  1. A \(\frac{27}{128}\)
  2. B \(\frac{81}{256}\)
  3. C \(\frac{81}{512}\)
  4. D \(\frac{27}{64}\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\frac{81}{512}\)

Step-by-step Solution

Detailed explanation

\(I_1 = \frac{I_0}{2}\) \(I_5 = I_1 (\cos^2 30^\circ)^4\) \(I_5 = \frac{I_0}{2} \left(\frac{\sqrt{3}}{2}\right)^8\) \(I_5 = \frac{I_0}{2} \left(\frac{3}{4}\right)^4\) \(I_5 = \frac{I_0}{2} \cdot \frac{81}{256}\) \(\frac{I_5}{I_0} = \frac{81}{512}\)