Sound Waves
W.3(1) - ORGAN PIPES
Vibrations within an organ pipe produce sound waves. Loud tones can be produced by blowing on the organ pipes or connecting them through a rubber hose to the air supply faucet. Three different tones are available and one wooden pipe with sliding piston.The resonant cavity's length can be varied to provide tones of varying pitch. In conjuction with a microphone, amplifier, and oscilloscope, the relationship between wave frequency and tone can be investigated.
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W.3(2) - ELECTRIC BUZZER IN VACUUM
This apparatus has a stand with an electric buzzer and a lamp, both connected to a remote switch. The vessel is covered by a large bell jar and is connected to a vacuum pump. While the jar in place and the lamp switch on the buzzer will ring. Now turn the vacuum pump on. Wait a few minutes while it evacuates the bell jar. The buzzer will ring fainter and fainter until it cannot be heard anymore. When the valve is opened the buzzer can be heard again. This demonstrates the need of a material medium for sound waves to propagate.
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W.3(3) - RESONANCE APPARATUS
Determine the standing wavelength of sound, using a tuning fork with a known frequency and a water filled tube. A tall stand holds a small water resevoir near its top and a 1.2 m plastic tube connected at its lower end to the bottom of the water's resevoir. The resevoir can be moved up and down the stand so that the tube's water level can be adjusted. A loud sound will be emmitted when a vibrating tuning fork is brought near the tube's opening and the water level is adjusted for the resonant cavity length. It can be used for resonance demonstrations and to determine the velocity of sound on air.
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