For a ray of light, the critical angle is minimum when it travels from

For a ray of light, the critical angle is minimum when it travels from
  1. air to glass.
  2. glass to water.
  3. water to glass.
  4. glass to air.

Solution

$\sin c=\frac{1}{\mu}$ $a\mu_{\mathrm{w}}=\frac{4}{3}, a \mu_{\mathrm{g}}=\frac{3}{2}, w \mu_{\mathrm{g}}=\frac{\mathrm{a} \mu_{\mathrm{g}}}{\mathrm{a} \mu_{\mathrm{w}}}=\frac{9}{8}$ Critical angle will be maximum when refractive index of the denser medium w.r.t. the rarer medium is minimum. $w \mu_{8}=\frac{9}{8}$ is minimum

Asked in: MHT CET 2020 (20 Oct Shift 2)

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