State the laws of refraction of light

• Reflection & Refraction (C10)

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

First Law of Refraction

The incident ray, refracted ray and normal to the interface at the point of incidence lie in the same plane.

Second Law of Refraction

The sine of angle of incidence bears a constant ratio with sine of angle of refraction for a given pair of media.

sin i / sin r = constant

Absolute refractive index of a medium

Absolute Refractive Index of a medium = Speed of light in air or vacuum / Speed of light in the medium