Speed of Sound by Air Resonance
To adjust a column of vibrating air to get resonance with a tuning fork of known frequency is a standard text book method to measure speed of sound in air at room temperature. In this experiment we suggest another arrangement for this measurement using the same basic principle.}
a speaker, a frequency generator, water in a bucket, a cylindrical tube (= 30 cm).
- Take water in the bucket and dip the cylindrical tube in it vertical. Hold it with one with most of the tube in air.
- Ask your friend to connect the speaker to the output of the frequency generator and put the speaker close to the open and of the tube. Make the frequency about 1~kHz. Keep the amplitude low so that surrounding the speaker is barely audible.
- Lower the tube and the speaker gradually and listen the sound. Adjust for the position where the sound intensity is maximum.
- Switch off the function generator. Measure the length of the tube above the water surface. This should be approximately \(\lambda/4\).
- Calculate the speed of sound in lab air from \(v=\nu\lambda\).