This applet is a tutorial explaining reflection and refraction of waves from the point of view of the Huygens' principle, step-by-step. At the end of each step, press the "Next step" button! You can stop and continue the simulation by using the "Pause / Resume" button. The three text fields make it possible to vary the index of refraction of both media and the angle of incidence. The medium with the smaller index of refraction (the bigger phase velocity) is painted yellow, the other blue.

From a collection of Java Applets on Physics.
Original © Walter Fendt, March 5, 1998.