Easy MCQ +4 / -1 PYQ · JEE Mains 2022

Light travels in two media $M_{1}$ and $M_{2}$ with speeds $1.5 \times 10^{8} \mathrm{~ms}^{-1}$ and $2.0 \times 10^{8} \mathrm{~ms}^{-1}$ respectively. The critical angle between them is :

  1. A $\tan ^{-1}\left(\frac{3}{\sqrt{7}}\right)$ Correct answer
  2. B $\tan ^{-1}\left(\frac{2}{3}\right)$
  3. C $\cos ^{-1}\left(\frac{3}{4}\right)$
  4. D $\sin ^{-1}\left(\frac{2}{3}\right)$

Solution

<p>Critical angle between them</p> <p>$\sin {i_c} = {{{\mu _2}} \over {{\mu _1}}} = {{{v_1}} \over {{v_2}}}$</p> <p>$\sin {i_c} = {3 \over 4}$</p> <p>$\Rightarrow \tan {i_c} = {3 \over {\sqrt 7 }}$</p> <p>${i_c} = {\tan ^{ - 1}}{3 \over {\sqrt 7 }}$</p>

About this question

Subject: Physics · Chapter: Optics · Topic: Reflection and Mirrors

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