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Question: Answered & Verified by Expert
Consider a tank made of glass (refractive index 1.5 ) with a thick bottom. It is filled with a liquid of refractive index μ. A student finds that, irrespective of what the incident angle i (see figure) is for a beam of light entering the liquid, the light reflected from the liquid glass interface is never completely polarized. For this to happen, the minimum value of μ is:

PhysicsWave OpticsJEE MainJEE Main 2019 (09 Jan Shift 1)
Options:
  • A 35
  • B 43
  • C 53
  • D 53
Solution:
2671 Upvotes Verified Answer
The correct answer is: 35


For reflected light not be completely polarized,

tanrμgμw=1.5μ

For minimum μ r is maximum. r is maximum when i is maximum i.e. i=90o

 sinr=1μ

 tanr=1μ2-1

1μ2-1=1.5μ

 μ2=2.25 μ2-1

 1.25 μ2=2.25

  μ=2.251.25

=95=35

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