PURPOSE: To demonstrate the origin of standing waves from two identical sources.
DESCRIPTION: Both speakers are driven by the same 3000 Hz sine wave from the audio oscillator, which is shown on the top trace of the oscilloscope. The standing wave pattern, observed by sliding a microphone along the optical rail between the speakers, is displayed on the lower trace.
REFERENCES: (PIRA unavailable.) See also demonstration H3-02: STANDING SOUND WAVES - REFLECTION, which uses the same setup except one of the loudspeakers is replaced by a plane reflector.
EQUIPMENT: Audio oscillator, two small speakers and microphone on optical rail, audio amplifier, and dual trace oscilloscope.
SETUP TIME: 10 min.
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