What is Snell's law ?

Snell's Law states that the ratio of the sine of the angles of incidence and transmission is equal to the ratio of the refractive index of the materials at the interface.

$n_{1} \times sin \theta_{ 1} = n_{2} \times sin \theta_{2}$

n1 = incident index

n2 = refracted index

$\theta_{ 1} =incident \ angle$

$\theta_{ 2} =refracted \ angle$