PURPOSE: To demonstrate standing sound waves in a closed tube.
DESCRIPTION: An oscillator drives a small loudspeaker which is mounted at one end of a tube, with the other end stopped by a moveable plunger. A microphone adjacent to the loudspeaker at the open end of the tube is connected to the oscilloscope. When the frequency is varied or the position of the plunger in the tube is changed, sound resonances can be created in the tube and are displayed on the oscilloscope as an increase in amplitude. Resonances occur when the length of the tube is equal to any odd multiple of one-quarter wavelength of the sound wave.
REFERENCES: (PIRA 3D30.16)
EQUIPMENT: Oscillator with small loudspeaker, pre-mounted tube with plunger and scale, microphone, and oscilloscope.
SETUP TIME: 5 min.
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