3B55.40-2 - Quincke's Interference Tube
To demonstrate interference of sound waves traveling through two different lengths of tube.
Make sure the Radio Mic receiver is sending a signal to the oscilloscope by tapping the table to see if the oscilloscope picks up the sound. To show a maximum, set the function generator to approximately 1282 Hz. To show a minimum, sweep the frequency up to around 1400 Hz.
Sound traveling through two different path lengths will interfere when the recombine. If the path length of the tube is chosen so that the length is a multiple of the incoming wavelength, then you can achieve an interference pattern with frequencies that will completely constructively and destructively add.