Waves and Resonances II
Measuring the Speed of Sound
In this experiment you will determine the
speed of sound in air by measuring the distance between antinodes for a fixed
frequency.
Required Equipment
Resonance tube consisting of a plexiglass
cylinder, microphone, water reservoir, audio-frequency oscillator and coaxial
cable.
CAUTION: Handle the resonance tube only
by the steel rod, not by the plexiglass tube. Otherwise, you may crack
the seal and cause the tube to leak.
Procedure
Fill the lowered reservoir with water. By
raising the reservoir, alter the resonant cavity length for longitudinal
vibrations of sound waves in the column. Listen for the maximum sound level
corresponding to the antinodes (half wavelengths) of a given frequency. Measure
as many antinodes as possible for at least five different frequencies.
Determine the velocity of sound in the
tube. Compare your results with that expected at the air temperature of your
experiment.
Try to answer the following:
1. From your data, is the open end of the tube
exactly an antinode?