A pipe open at both ends has a fundamental frequency 'f' in air. The pipe is dipped in water, so that 2/3rd length of pipe is in water, Now the fundamental frequency of the air column is (a) 1/2f (b) 3/2f (c) 5/2f (d) 7/2f

Answer: (b). Open pipe of length L: f = v/2L. Dipping in water closes the lower end; air column left = L - 2/3L = L/3 (closed pipe). f' = (v)/(4(L/3)) = 3v/4L = 3/2/2L So the answer is (b) 3/2f.

A pipe open at both ends has a fundamental frequency 'f' in air. The… | MHT CET 2026 (15 Apr, Shift 2)

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Organ Pipes & Resonance Tube

A pipe open at both ends has a fundamental frequency 'f' in air. The pipe is dipped in water, so that ${\frac{2}{3}}^{rd}$ length of pipe is in water, Now the fundamental frequency of the air column is

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Answer: (b)

Open pipe of length $L$ : $f = \frac{v}{2L}$ .
Dipping in water closes the lower end; air column left $= L - \frac{2}{3}L = \frac{L}{3}$ (closed pipe).
$f' = \frac{v}{4(L/3)} = \frac{3v}{4L} = \frac{3}{2}\cdot\frac{v}{2L}$
So the answer is (b) $\frac{3}{2}f$ .

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Organ Pipes & Resonance Tube question from MHT CET 2026 (15 Apr, Shift 2)

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