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JEE Main 2019 — Wave Optics Question with Solution

JEE Main 2019 (09 Jan Shift 1)

Question

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:

Choose an option

Show full solutionCorrect option: A
Correct answer
A35

Step-by-step explanation



For reflected light not be completely polarized,

tan⁡r≠μgμw=1.5μ

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

⇒ sin⁡r=1μ

⇒ tan⁡r=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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About this question

This is a previous-year question from JEE Main 2019, covering the Wave Optics chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.