PURPOSE: To demonstrate the wave properties of diffraction and interference.
DESCRIPTION: A ripple tank consists of a shallow water tank supported above a 45 degree mirror. A point source illuminates the water, reflects off the mirror and casts an image of the water onto a ground glass screen as shown in the above photo at left. Each water wave acts much like a curved lens; The crest of the wave is seen as a bright region and the the trough of the wave is seen as a dark region.
Inside the ripple tank is a mechanical vibrator attached to a paddle that produces either point wavelets or parallel wavefronts. Various obstructions and barriers can be inserted into the path of the wave, such as a single slit, a double slit or an edge. The assembled ripple tank is shown in the photo at right.
EQUIPMENT: Ripple tank set up, as photographed.
SETUP NOTES:
Updated by Jun Qi in 4/5/2000