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.

Explanation

1st law: The incident ray, refracted ray and normal to the interface at the point of incidence lie in the same plane.
2nd law: The sine of angle of incidence bears a constant ratio with sine of angle of refraction for a given pair of media. Or `(sin i)/(sin r)` = constant
Absolute refractive index of a medium = `("Speed of light in air(c) or vaccum")/("Speed of light in medium (v)")`
(Award full marks if the same thing is given in the form of statement)