Purpose:Demonstrate the phase of pulses reflected from open ends and closed ends of a tube.
Description:A pulse is created by the leading edge of a low-frequency square wave input into a loudspeaker at one end of a long, rigid plastic tube. This pulse travels along the tube and is reflected back and forth at the ends. The phase of the pulse as it reflects back and forth is observed using a microphone inserted into the center of the tube. Several reflections can be observed. It is easy to see the difference between reflection at the open end and reflection at a closed end, obtained by placing a metal plate against the end of the tube opposite the loudspeaker.