Question 1

Why does an open organ pipe support all integral harmonics?

Accepted Answer

Both ends of an open pipe are displacement antinodes and pressure nodes. This boundary condition permits standing waves whose effective length is an integral multiple of half a wavelength, giving frequencies f_n = nv/(2L_eff).

Question 2

Why are even harmonics absent in a one-end-closed organ pipe?

Accepted Answer

The closed end must remain a displacement node, while the open end is a displacement antinode. Only odd quarter-wave patterns satisfy both conditions, so the allowed frequencies are 1, 3, 5 and 7 times the fundamental.

Question 3

What happens in a closed-closed air column?

Accepted Answer

Both ends of an ideal closed-closed air column are displacement nodes and pressure antinodes. Its fundamental effective length is lambda/2, and it supports all integral harmonics: 1, 2, 3, 4 and so on.

Question 4

What is the difference between a harmonic and an overtone?

Accepted Answer

A harmonic is an allowed natural frequency numbered from the fundamental: H1, H2, H3 and so on. An overtone counts frequencies above the fundamental, so the first overtone is H2 in an open or closed-closed column and H3 in a one-end-closed column.

Question 5

When does a tuning fork produce resonance in an organ pipe?

Accepted Answer

Resonance occurs when the fork frequency matches an allowed natural frequency of the pipe. An open or closed-closed column can resonate at all integral multiples of its fundamental, while a one-end-closed column can resonate only at odd multiples.

Organ Pipe Harmonics Lab — Open, Closed and Missing Even Notes

About this lab

Practice