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JEE Main 201816 AprilOnline
Exam
JEE Main
Year
2018
Date
16 April
Mode
Online
Subject
Physics
Chapter
Wave Optics

JEE Main 2018 · 16 April · Online · Physics · Wave Optics

Unpolarized light of intensity I is incident on a system of two...

Unpolarized light of intensity II is incident on a system of two polarizers, AA followed by BB. The intensity of emergent light is I2\dfrac{I}{2} . If a third the polarizer CC is placed between AA and BB the intensity of emergent light is reduced to I3\dfrac{I}{3} . The angle between the polarizers AA and CC is θ\theta , thenUnpolarized light of intensity I is incident on a system of two polarizers, A followed by B . The intensity of emergent

Options

  1. Acos \theta = {\left(\dfrac{2}{3}\right)}^{\dfrac{1}{4}}
  2. Bcos \theta = {\left(\dfrac{1}{3}\right)}^{\dfrac{1}{4}}
  3. Ccos \theta = {\left(\dfrac{1}{3}\right)}^{\dfrac{1}{2}}
  4. Dcos \theta = {\left(\dfrac{2}{3}\right)}^{\dfrac{1}{2}}

Correct answer

A. cos \theta = {\left(\dfrac{2}{3}\right)}^{\dfrac{1}{4}}

Step-by-step solution

Unpolarized light of intensity I is incident on a system of two polarizers, A followed by B . The intensity of emergent

A and B have the same alignment of the transmission axis. Let's assume cc is introduced at θ\theta angle, ⇒I2cos⁡2θ×cos⁡2θ=I3⇒ \dfrac{I}{2}\cos^{2}\theta \times \cos^{2}\theta = \dfrac{I}{3}⇒cos⁡4θ=23⇒ \cos^{4}\theta = \dfrac{2}{3}
⇒cosθ=(23)14⇒ cos\theta = \left(\dfrac{2}{3}\right)\dfrac{1}{4}.
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