Question

Light enters from air to glass having refractive index 1.50. What is the speed of light in the glass? The speed of light in vacuum is 3 × 108 m s−1.

Answer 1

Refractive index of a medium nm is given by,
$n_m = \frac{\text{Speed of light in vacuum}}{\text{Speed of light in the medium }}$
$=\frac{ c }{v}$
Speed of light in vacuum, c = 3 × 108 m s−1
Refractive index of glass, ng = 1.50
Speed of light in the glass,
$v=\frac{c}{n_g}$

$=\frac{3\times10^8}{1.50}$
$=2\times10^8$ ms-1