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JEE Main 2013 · Polarisation

Polarisation question from JEE Main 2013

Q60JEE Main 2013Easy

Polarisation

A beam of unpolarised light of intensity I0I_0 is passed through a polaroid AA and then through another polaroid BB which is oriented so that its principal plane makes an angle of 45∘45^\circ relative to that of AA. The intensity of the emergent light is

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Answer: (c)

  1. After A: I1=I02I_1 = \dfrac{I_0}{2}.
  2. After B: I2=I02cos⁡245∘=I02×12I_2 = \dfrac{I_0}{2}\cos^2 45^\circ = \dfrac{I_0}{2}\times\dfrac{1}{2}
  3. I2=I04I_2 = \dfrac{I_0}{4}
  4. So the answer is (c) I04\dfrac{I_0}{4}.
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