Snell's law

 Snell's law

Snell’s law is defined as “The ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant, for the light of a given colour and for the given pair of media”. Snell’s law formula is expressed as:

Where i is the angle of incidence and r is the angle of refraction. This constant value is called the refractive index of the second medium with respect to the first.