When an organ pipe, which is closed at one end only, vibrates with a frequency that is 3 times its fundamental first harmonic) frequency,
A) the sound produced travels at 3 times its former speed.
B) the sound produced is its fifth harmonic.
C) beats are produced.
D) the sound produced has one-third its former wavelength.
E) the closed end is a displacement antinode.

Question

Quizplus · Accepted Answer

When the frequency is three times the fundamental frequency (third harmonic), the wavelength is one-third of the wavelength of the fundamental frequency. Since the pipe is closed at one end, the closed end is a displacement node, not an antinode. The speed of sound in air is constant, so the sound produced does not travel at a different speed. The produced sound is not the fifth harmonic, but the third harmonic with three times the frequency of the fundamental. Since there is no second frequency present, beats are not produced.

When an Organ Pipe, Which Is Closed at One End