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Resonance tube experiment
Intermediate
Finds speed of sound from resonance lengths.
v = 2f(l₂−l₁)A tuning fork over a tube with adjustable water level. Resonance happens at successive lengths l₁ and l₂, and v = 2f(l₂ − l₁), which eliminates end correction.
f = 512 Hz, l₂ − l₁ = 33.5 cm: v = 343 m/s.
Use the difference of two resonances.
In more detail
In a resonance tube experiment, a tube partly filled with water is held over a vibrating tuning fork. The water level is adjusted until resonance is heard, and the wavelength is found from the separation of successive resonances.
Real-world uses
- School labs measure the speed of sound in air with this method.
- It demonstrates the relation between wavelength and tube length.
- A school experiment finds the speed of sound by moving a tube of water and noting the resonance lengths.
Open the interactive lesson, with simulation and quiz →
Frequently asked questions
Why is the separation half a wavelength?
Successive resonances in a closed tube are separated by half a wavelength.
What is the main source of error?
The end correction and reading the water level accurately.
Why use two resonance lengths?
The difference between them gives half a wavelength directly, which removes the end correction from the calculation.
Related topics in Waves & Sound
Closed organ pipe · End correction · Kundt's tube · Sound as pressure waves · Pitch and frequency · Loudness and intensity