Question

10.(c) A pipe closed at one end has fundamental frequency of 200Hz. The frequency of the first overtone of the closed pipe is equal to the frequency of the first overtone of an open pipe. Calculate the: (i) Fundamental frequency of the open pipe; (ii) Length of the closed pipe; (iii) Length of the open pipe. [Speed of sound in air = 330ms⁻¹]

Accepted Answer

Closed pipe: f₀=200Hz, first overtone = 3f₀ = 600Hz.
(i) For the open pipe, first overtone = 2f₀' = 600Hz → f₀' = 300Hz.
(ii) Length of closed pipe: f₀=v/4L → L = 330/(4×200) = 0.4125m.
(iii) Length of open pipe: f₀'=v/2L' → L' = 330/(2×300) = 0.55m.

WAEC Physics 2018 Theory — Question 20

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