Standing waves in air, quite analogous to the standing waves on a string, can be produced in the air column inside a cylindrical tube. An aluminum plug may be moved along the tube and the presence of the standing wave detected by listening for nodes and anti-nodes in the standing wave pattern. In this case, the excitation is provided by a small speaker driven by a function generator. The arrangement is sketched below.
frequency of the function generator to 1000 Hz.
Starting with the movable piston near the speaker, move the piston away
from the end until the sound reaches a minimum.
Record the position of this minimum intensity, which is found when the
end of the tube is at a node. Continue to
move the piston along the tube, recording all the rest of the points along the
tube where the sound is weakest.
Average the distances between these successive nodes, find the
corresponding wavelength which is twice the average distance, and use Eq.(1) to
calculate the speed of sound in air.
Obtain a 90% confidence interval for this
measurement by propagating the uncertainty in node separation.
Obtain a 90% confidence interval for this measurement by propagating the uncertainty in node separation.
velocity of sound in air is known to vary with temperature as:
your value of v measured for the standing wave with the one found from Eq.(3).
For this comparison, you can assume that the uncertainty in the value from Eq.(3)