Physics › Section L · Sound and hearing › Topic L.4
Standing waves in air columns
Blow across the open end of an empty pen cap and it sings one clear note. Air trapped in a tube can only vibrate at certain frequencies, and those frequencies, fixed by the tube's length and whether its ends are open or closed, are what give flutes, clarinets and organ pipes their notes.
In this topic
- Why a tube picks out notes
- Nodes and antinodes in air
- Tubes closed at one end
- Worked example: tuning a closed pipe
- Tubes open at both ends
- Worked example: an open pipe and a closed one
- Harmonics, overtones and timbre
- Worked example: measuring the speed of sound
- Temperature and tuning
- Common mistakes to avoid
- Key takeaways
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