Q138 / 180 · JIPMER 2019 · Physics

When a light ray enters from oil to glass on oil- glass interface, then velocity of light changes by a factor of [given, $\mu_{\text {oil }}=2, \mu_{\text {glass }}=3 / 2$ ]

  • Correct answer
    A
    $\frac{4}{3}$
  • B
    $\frac{3}{4}$
  • C
    3
  • D
    1

Solution

Given, $\mu_{\text {oil }}=2$ and $\mu_{\text {glass }}=3 / 2$ velocity of light in oil is given by $\begin{aligned} & \mathrm{V}_{\text {oil }}=\frac{\text { Velocity of light (c) }}{\mu_{\text {oil }}}=\frac{\mathrm{c}}{\mu_{\text {oil }}} \\ \text { Similarly, } \mathrm{V}_{\text {glass }} & =\frac{\mathrm{c}}{\mu_{\text {glass }}} \\ \therefore \quad & \frac{V_{\text {glass }}}{\mathrm{V}_{\text {oil }}}=\frac{\mathrm{c} / \mu_{\text {glass }}}{\mathrm{c} / \mu_{\text {oil }}}=\frac{\mu_{\text {oil }}}{\mu_{\text {glass }}}=\frac{2}{3 / 2}=\frac{4}{3} \end{aligned}$

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

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