
Aim: to measure the Speed of Sound in a Resonance Tube 
See Resonance in Tubes Closed at One End 

Sound travels slightly more slowly inside a tube
compared with its speed in open air. 

Method 
A convenient way to measure the speed involves
finding the lengths at which an air column resonates for
a range of frequencies. 
Set up apparatus similar to that shown below. 

Set the generator to a known frequency and vary the
length of the air column (by lowering or raising the
tube into or out of the water). 
Some preliminary calculations will be needed to know
approximately what range of frequencies will be suitable
for the lengths of air column being investigated. 
When resonance occurs, a loud sound will be heard. 
Note the frequency and the length of the air column. 

The calibration of many signal generators is
approximate. 
Use a frequency meter to measure the frequencies
supplied by the generator. 
A frequency meter is connected in the same way as a
voltmeter. 

Analysis of results 
It has been shown that, at the fundamental
resonance, the length of the tube is given by 

where e is the end correction and
λ is the
wavelength of the sound. 
Rearranging this equation a teeny bit gives 

so if we plot a graph of L against 1/f_{o}
we should have a straight line which will allow us to
find both the speed of sound and the end correction of
the tube. 

The end correction is usually taken to be about 0.6
times the radius of the tube. 
See if your results agree with
this... 