# Difference between revisions of "Snell's Law"

Snell's Law describes how the direction of light changes when it moves from one medium to another. The two forms of the law are:

n1 sin(θ1) = n2 sin(θ2)
v2 sin(θ1) = v1 sin(θ2)

where:

n1 and n2 are the indices of refraction in media 1 and 2, respectively
v1 and v2 are the velocities of light in media 1 and 2, and
θ1 and θ2 are the angle from the normal of the plane dividing the 2 media and the ray.

The index of refraction of a material is inversely proportional to the speed of light in that material, i.e. light will move slower in a material with a high index of refraction than it will in a material with a low index of refraction.

What Snell's Law says is that when light moves from a medium with a high index of refraction to a medium with a low index of refraction it will bend away the normal of the plane dividing the two media. Conversely, when light moves from a medium with a low index of refraction to a medium with a high index of refraction it will bend towards from the normal dividing the two media.

One other theory is that the direction changes due to God's will.