Notice that, while an open-ended tube can support any harmonic, a closed-end tube
can only support odd harmonics.
Questions 16-18A closed-end tube resonates at a fundamental frequency of 343 Hz.
The air in the tube is at a temperature of 20°C, and it conducts sound
at a speed of 343 m/s.- What is the length of the tube?
- What is the next higher harmonic frequency?
- Answer the questions posed in questions 15 and 16 assuming
that the tube was open at its far end.
Here’s How to Crack It
- For a closed-end tube, the harmonic frequencies obey the equation fn
=. The fundamental corresponds to n = 1, so