Generating Waves in a Ripple Tank

The apparatus used for ripple tank movies is described.

Discussion

The most important objects in this setup are, from top to bottom, a point light source (not visible in most of the ripple tank movies that follow), a mechanical wave driver and wave source, the ripple tank, and a digital wave generator. The mechanical wave driver moves the point or linear wave source up and down on the surface of the water in the ripple tank, creating, respectively, circular or linear ripples or waves. The frequency setting selected on the digital wave generator determines the wave frequency.

An image of the ripples in the tank can be seen on the table top beneath the ripple tank. Wave peaks or crests on the surface of the water act as convergent lenses that focus light from the point source to produce a bright area in the ripple tank image of the wave peak on the table top; where there is a wave trough, the water acts as a divergent lens, and produces a dark area in the image. In the movies that follow, you will see close-ups of ripple tank images that illustrate a variety of wave phenomena.