Home / Topics / Waves & Sound
End correction
Advanced
Antinode lies slightly beyond an open end.
e ≈ 0.6rThe antinode sits slightly beyond the open end of a pipe, so the effective length is L + 0.6r (one open end). It matters for accurate resonance calculations.
r = 2 cm adds 1.2 cm.
Ignoring it gives errors for fat pipes.
In more detail
The end correction accounts for the fact that the antinode at an open end of a pipe lies slightly outside the pipe. It makes the effective length slightly longer than the physical length.
Real-world uses
- Precision resonance experiments correct measured pipe lengths.
- Designers of wind instruments include end corrections in tuning.
- Organ builders correct the length of pipes by adding a small end correction, so the tuning matches the design frequency.
Open the interactive lesson, with simulation and quiz →
Frequently asked questions
How large is the end correction?
About 0.6 times the pipe radius for each open end.
Why is it important?
It can change the calculated speed of sound by several percent if ignored.
Why is the pipe effectively longer than its length?
The air at the open end moves beyond the physical end, so the antinode sits slightly outside the pipe.
Related topics in Waves & Sound
Harmonics and overtones · Open organ pipe · Closed organ pipe · Kundt's tube · Resonance tube experiment · Sound as pressure waves