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JEE Main 2023 (1 Feb, Shift 1) · Polarisation

Polarisation question from JEE Main 2023 (1 Feb, Shift 1)

Q40JEE Main 2023 · 1 FEB · SHIFT 1Difficult

Polarisation

'nn' polarizing sheets are arranged such that each makes an angle 45∘45^\circ with the preceding sheet. An unpolarized light of intensity I is incident into this arrangement. The output intensity is found to be I/64I/64. The value of nn will be:

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Answer: (d)

  1. First sheet: I/2I/2; each of the other (n−1)(n-1) sheets multiplies by cos⁡245∘=12\cos^2 45^\circ = \frac{1}{2}.
  2. Iout=I2n=I64⇒2n=64I_{out} = \frac{I}{2^n} = \frac{I}{64} \Rightarrow 2^n = 64
  3. So the answer is (d) n=6n = 6.
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