Calculator Inputs
Choose the tube type, decide what to solve, and enter values in SI units.
Example Data Table
Sample values below use an open-closed tube, 20°C air, 0.015 m radius, and 0.60 correction factor per open end.
| Harmonic n | Frequency (Hz) | Effective Length (m) | End Correction (m) | Physical Length (m) | Wavelength (m) |
|---|---|---|---|---|---|
| 1 | 250 | 0.343 | 0.009 | 0.334 | 1.372 |
| 3 | 250 | 1.029 | 0.009 | 1.02 | 1.372 |
| 5 | 250 | 1.715 | 0.009 | 1.706 | 1.372 |
Formula Used
1) Sound speed from air temperature
v = 331.3 + 0.606T, where T is temperature in °C and v is in m/s.
2) End correction
ΔL = e × k × r, where e is the number of open ends, k is the end correction factor per open end, and r is the tube radius.
3) Effective length
Leff = L + ΔL, where L is the physical tube length.
4) Open-open resonance
Leff = nλ/2, so f = nv / 2Leff and λ = 2Leff / n.
5) Open-closed resonance
Leff = nλ/4, so f = nv / 4Leff and λ = 4Leff / n. Here, n must be odd.
How to Use This Calculator
- Choose whether the tube is open at both ends or open at one end.
- Pick what you want to solve for: physical length, frequency, or wavelength.
- Select sound speed mode. Use temperature for air, or enter a custom value.
- Enter the harmonic number. For open-closed tubes, use only odd values.
- Provide tube radius and the end correction factor so the effective length is adjusted realistically.
- If solving for length, enter frequency. Otherwise, enter the physical tube length.
- Click Calculate Resonance to show the result above the form, review the graph, and download CSV or PDF summaries.
Frequently Asked Questions
1) What does a resonance tube calculator measure?
It estimates how tube length, wavelength, frequency, sound speed, and harmonics relate during standing-wave resonance. It also accounts for end correction, which improves real-world accuracy compared with ideal equations.
2) Why is end correction important?
Air motion extends slightly beyond an open end, so the acoustic length is longer than the physical tube. End correction compensates for that difference and makes predicted resonance frequencies more realistic.
3) Why are only odd harmonics allowed in an open-closed tube?
An open-closed tube has a displacement node at the closed end and an antinode at the open end. That boundary pattern supports only odd quarter-wave multiples, so even harmonics are not valid.
4) How does temperature affect the answer?
Higher air temperature increases sound speed. Since resonance frequency depends on sound speed, warmer air raises predicted frequencies for the same effective tube length.
5) Can I use this for laboratory experiments?
Yes. It is useful for classroom and lab estimates, especially when you know tube radius, temperature, and harmonic number. Measured results may still vary because of humidity, imperfect tube geometry, and instrument limitations.
6) What units should I enter?
Use meters for lengths and radius, hertz for frequency, meters per second for sound speed, and degrees Celsius for temperature. Keeping consistent SI units avoids scaling errors.
7) Does the graph use the solved result?
Yes. After calculation, the graph uses the solved effective length and plots the first allowed harmonic frequencies for the selected tube type, giving a quick view of the harmonic pattern.
8) What if my measured value differs from the output?
Check temperature, harmonic number, radius, and end correction first. Small input changes can matter. Experimental differences may also come from tube shape, microphone placement, and ambient noise.