Snells law – Light – Laws of Refraction
Refractive Index is the extent of change of direction of light in a given pair of media. The refractive index is a relative value of the speed of light in the given pair of media.
The ratio of sine of the angle of incidence to the sine of the angle of refraction is a constant, for the light of a given color and for the given pair of media. This law is also known as Snell’s law of refraction. If i is the angle of incidence and r is the angle of refraction, then,
sin i / sin r = n21=constant
This constant value is called the refractive index of the second medium with respect to the first.
Sin is the trigonometric function.