Medium MCQ +4 / -1 PYQ · JEE Mains 2022

Consider a light ray travelling in air is incident into a medium of refractive index $\sqrt{2n}$. The incident angle is twice that of refracting angle. Then, the angle of incidence will be :

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

Solution

<p>According to the law,</p> <p>$$1 \times \sin \theta = \sqrt {2n} \times \sin \left( {{\theta \over 2}} \right)$$</p> <p>$\Rightarrow \cos {\theta \over 2} = \sqrt {{n \over 2}}$</p> <p>$\Rightarrow \theta = 2{\cos ^{ - 1}}\left( {\sqrt {{n \over 2}} } \right)$</p>

About this question

Subject: Physics · Chapter: Optics · Topic: Refraction and Snell's Law

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