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A closed pipe has a node at the closed end and an antinode at the open end. This asymmetric boundary condition allows only odd harmonics: $f_n = (2n-1)v/(4L)$ for $n = 1, 2, 3, ...$, giving frequencies $f_1, 3f_1, 5f_1, 7f_1, ...$. The fundamental $f_1 = v/(4L)$ is half that of an open pipe of the same length. The first overtone is the 3rd harmonic, the second overtone is the 5th harmonic — a common source of exam errors when confusing overtone number with harmonic number.

The resonance tube experiment uses a closed pipe with adjustable length (water level). First resonance at $L_1 \approx \lambda/4$, second at $L_2 \approx 3\lambda/4$, third at $L_3 \approx 5\lambda/4$. The key relation $\lambda/2 = L_2 - L_1$ eliminates end correction and gives the speed of sound directly: $v = 2f(L_2 - L_1)$. End correction can be found: $e = (L_2 - 3L_1)/2$.

To distinguish between open and closed pipes from given resonance frequencies: in an open pipe, consecutive resonance frequencies differ by $f_1$; in a closed pipe, they differ by $2f_1$. Also check if only odd multiples of $f_1$ are present.