Question

Two consecutive harmonics of air column in a pipe closed at one end are frequencies 150 Hz and 250 Hz. Calculate the fundamental frequency.

Answer 1

Frequency of 1^st harmonic, n₁ = 150 Hz.

Frequency of consecutive harmonic, n₂ = 250 Hz. For a pipe closed at one end

Frequency of 1st harmonic = 3n = n₁

Frequency of second harmonic = 5n = n₂

∴ Fundamental frequency is given by

∴ `n_1 = 3n ⇒ 150 = 3n`

∴ `n = 150/3 = 50 Hz.`