Question

State the laws of refraction of light. Explain the term 'absolute refractive index of a medium' and write an expression to relate it with the speed of light in vacuum.

Answer 1

Snell's laws of refraction of light :
(1) : The incident ray, refracted ray and normal to the refracted surface lie in the same plane.
(2) : Ratio of the sine of the angle of incidence in medium 1 to that of the angle of refraction in medium 2 is equal to the ratio of the refractive index of medium 2 to that of 1.
$⟹\frac{\sin i}{\sin r}=\frac{n_2}{n_1}$
Absolute refractive index of the medium is defined as the refractive index of that medium with respect to refractive index of vacuum i.e. ratio of refractive index of the given medium to that of vacuum.
Absolute refractive index of medium $=\frac{n_{medium}}{n_{vacuum}}=\frac{c}{v}$
where $v$ is the speed of light in that medium, $c$ is the speed of light in vacuum.