Refraction and Reflection
The refraction is described by Snell's law, which is given by:
sinθ1 / sinθ2 = v1/v2 = n2/n1
Where we have:
θ1 and θ2 are the angle of incidence and refraction respectively. Note θ1 = θ3
v1 and v2 are the velocities of the wave from medium 1 to medium 2
n1 and n2 are the refractive indices
The ratio of the refractive indices from medium 1 to medium 2 can be determined by:
n12 = sinθ1 / sinθ2
or
n12 = v1/v2