Sound Waves in an Organ Pipe


In class we found that standing waves are produced in an organ pipe with one closed end when the air inside is excited with a tuning fork. The simulation below illustrates the longitudinal nature of such waves; the air molecules are displaced parallel to the direction in which the wave carries energy.

The wave within the tube is a standing wave

y(x,t) = 2Asin( 2p
l
x) cos( 2pv
l
t)
with velocity determined by the physical characteristics of the medium (air)

v =   æ
Ö

gP0
r0
 

and fitting an odd number of quarter-wavelengths within the tube. In this applet the length of the tube is 2 m.