Purpose:Demonstrate constructive and destructive interference using pulses.
Description:Starting identical pulses from both ends simultaneously, either in or out of phase, they can be observed as they pass. For two identical pulses, move your hand rapidly down and up at the center of the machine with the two ends fixed. The two pulses created will reflect off the ends (left photograph) and interfere constructively as they cross each other on their return (right). Repeat this with one end clamped to get a phase reversal of the pulse which reflects off that end.