Physics 225  -  Fall 2006
Wave and Group velocity demonstrations

These links give some demonstrations of beats which result when traveling waves are added together.

• Two waves are added. The wave functions are given in the form A sin(k(x-vt)). The demonstration starts with two identical waves. (hit "forward" to make the waves go.) The sum shows no beats. Before you change k or v, click on the links for "linear dispersion" and "non linear dispersion". In each case one of the waves gets a changed k value, so you expect beats to appear. The example called "linear dispersion" has the same wave speed for both waves, while the "non linear dispersion" example shows a case where for different k the waves have different speed. (I would call the first example no dispersion, and the second example dispersion.)
  
  
• Wave Packets Examples of wave packets with and without dispersion. (No dispersion means the wave and group velocities are the same.)
  
  
• Some movies of "beats" made combining five sine waves. (needs Quick Time player)
  
  
• A demo adding two waves where you can set the group velocity and frequency.