State the laws of refraction of light. Explain the term absolute refractive index of a medium

Question

(i) 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.
(ii) The absolute refractive indices of two media 'A' and 'B' are 2.0 and 1.5 respectively. If the speed of light in medium 'B' is 2 x 10⁸ m/s calculate the speed of light in :
(a) vacuum
(b) medium 'A'

Answer 1

(i) Laws of refraction of light :
(a) The incident ray, the normal and the refracted ray at the point of incidence all lies in the same plane for the two given transparent medium.
(b) The ratio of size of angle of incidence (i.e., sin i) to the sine of angle of refraction (i.e., sin r) is always constant for the light of given colour and for the given pair of media.