Question

Find the fundamental, first overtone and second overtone frequencies of a pipe, open at both the ends, of length 25 cm if the speed of sound in air is 330 m/s.

Answer 1

Given : Open pipe, L= 25 cm = 0.25 m, v = 330 m/s

The fundamental frequency of an open pipe ignoring end correction,

n_O = v/λ = v/2L

∴ n_O = \(\frac{330}{2×0.25}\)  = 660 Hz

Since all harmonics are present as overtones, the first overtone is,

n₁ = 2n_O = 2 x 660 = 1320 Hz

The second overtone is

n₂ = 3n_O = 3 x 660 = 1980 Hz