Easy MCQ +4 / -1 PYQ · JEE Mains 2022

The speed of light in media 'A' and 'B' are $2.0 \times {10^{10}}$ cm/s and $1.5 \times {10^{10}}$ cm/s respectively. A ray of light enters from the medium B to A at an incident angle '$\theta$'. If the ray suffers total internal reflection, then

  1. A $\theta = {\sin ^{ - 1}}\left( {{3 \over 4}} \right)$
  2. B $\theta > {\sin ^{ - 1}}\left( {{2 \over 3}} \right)$
  3. C $\theta < {\sin ^{ - 1}}\left( {{3 \over 4}} \right)$
  4. D $\theta > {\sin ^{ - 1}}\left( {{3 \over 4}} \right)$ Correct answer

Solution

<p>${\mu _A} = {{3 \times {{10}^8}} \over {2 \times {{10}^8}}} = 1.5$</p> <p>${\mu _B} = {{3 \times {{10}^8}} \over {1.5 \times {{10}^8}}} = 2$</p> <p>For TIR</p> <p>$\theta > {i_c}$</p> <p>$\theta > {\sin ^{ - 1}}\left( {{{1.5} \over 2}} \right)$</p> <p>$\theta > {\sin ^{ - 1}}\left( {{3 \over 4}} \right)$</p>

About this question

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

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