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, n_g = 1.50 
Speed of light in the glass,
\(v=\frac{c}{n_g}\)

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