Q154 / 170 · Manipal (MET) 2019 · Physics

Light travelling from a transparent medium to air undergoes total internal reflection at an angle of incidence of $45^{\circ}$. Then refractive index of the medium may be

  • Correct answer
    A
    $1.5$
  • B
    $1.3$
  • C
    $1.1$
  • D
    $1 / \sqrt{2}$

Solution

At $45^{\circ}$ total internal reflection takes place so, critical angle, $C=45^{\circ}$. Refractive index, $\mu=\frac{1}{\sin C}=\frac{1}{\sin 45^{\circ}}$ $\begin{aligned} & =\sqrt{2}=1.414 \\ & \approx 1.5 \end{aligned}$

Hence, the correct answer is option: 'A'.

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