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NEET 2025 · Polarisation

Polarisation question from NEET 2025

Q16NEET 2025Easy

Polarisation

The intensity of transmitted light when a polaroid sheet, placed between two crossed polaroids at 22.5∘22.5^\circ from the polarization axis of one of the polaroids, is ( I0I_0 is the intensity of polarised light after passing through the first polaroid):

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Answer: (a)

  1. Middle sheet at 22.5∘22.5^\circ to the first, so at 67.5∘67.5^\circ to the last (crossed).
  2. I=I0cos⁡222.5∘cos⁡267.5∘=I0(cos⁡22.5∘sin⁡22.5∘)2I = I_0\cos^2 22.5^\circ\cos^2 67.5^\circ = I_0(\cos 22.5^\circ \sin 22.5^\circ)^2
  3. I=I04sin⁡245∘=I04×12I = \dfrac{I_0}{4}\sin^2 45^\circ = \dfrac{I_0}{4}\times\dfrac{1}{2}
  4. So the answer is (a) I08\dfrac{I_0}{8}.
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