Waves: Refraction
This interactive applet shows a wave's refraction (change in direction) by crossing the interface between two media, due to the different refractive indices or velocities on both sides of the interface. You can change the angle of incidence (alpha1) by moving the point A1. And with sliders, you can change the frequency of the wave and the ratio between velocities (or wave lengths, or refractive indices). The angle of refraction (alpha2) is calculated using Snell's law.