If light travels in the air with the speed of 3 x 10⁸ m/s, then what will be the speed of light in a medium with a refractive index of  3/2?

The refractive index of a medium:

$\mathrm{\mu }=\frac{\mathrm{Speed} \mathrm{of} \mathrm{light} \mathrm{in} \mathrm{vacuum}\left(\mathrm{C}\right)}{\mathrm{Speed} \mathrm{of} \mathrm{light} \mathrm{in} \mathrm{medium} \left({\mathrm{v}}_{\mathrm{medium}}\right)}$

Refractive index, $\mathrm{\mu } = 3/2 = 1.5$

C = 3 x 10⁸ m/s

${\mathrm{V}}_{\mathrm{medium}} = \frac{\mathrm{C}}{\mathrm{\mu }}= \frac{3 \times {10}^8}{1.5}$

${\mathrm{V}}_{\mathrm{medium}} = 2 \times {10}^8 \mathrm{m}/\mathrm{s}$

Therefore the speed of light in the given medium will be 2 x 10⁸ m/s.