Shown in the photograph below are two aluminum tubes. They have the same length, but the tube on the right has a cap on one end. Physicists would say the the tube at the left is "open" and the tube at the right is "closed." If you click your mouse on the photograph below you will hear Gwen creating a musical tone by blowing across one end of the open tube.

 

Now suppose that Gwen were to blow across the open end of the closed tube. How would you compare the frequencies of the tones of the tubes?

The frequency of the closed tube is:

• (a) higher than that of the open tube.
• (b) lower than that of the open tube.
• (c) the same as that of the open tube.

After April 18th, 2014, click Read More for the Answer

 The answer is (b): the frequency of the closed tube is lower than that of the open tube, which can be heard in an mpeg video by clicking your mouse on the photograph below.

In fact, the frequency of the closed tube is approximately one octave - a factor of two in frequency - below that of the open tube.