1. 2L 2. L/2 3. 4L 4. L

Answer: 1. 2L Compare the frequencies using v as the speed of sound. Open pipe of length l : harmonics nv/2l ; the second overtone is the 3rd harmonic, f=3v/2l . Closed pipe of length L : odd harmonics only; the first overtone is the 3rd harmonic, f=3v/4L . Equal frequencies: 3v/2l=3v/4L , so l=2L . Option (1).

Topic: Standing waves in strings and organ pipes, harmonics· Oscillations and Waves

The second overtone of an open organ pipe has the same frequency as the first overtone of a closed pipe L metre long. The length of the open pipe will be

1. \(2L\)

2. \(\frac{L}{2}\)

3. \(4L\)

4. \(L\)

Doubtly Asked 30 Oct 2026 NEET UG 2016 Phase 2 Practice test neet Save WhatsApp Report

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Answer: 1. \(2L\)

Compare the frequencies using \(v\) as the speed of sound.

Open pipe of length \(l\): harmonics \(n\dfrac{v}{2l}\); the second overtone is the 3rd harmonic, \(f=\dfrac{3v}{2l}\).
Closed pipe of length \(L\): odd harmonics only; the first overtone is the 3rd harmonic, \(f=\dfrac{3v}{4L}\).

Equal frequencies: \(\dfrac{3v}{2l}=\dfrac{3v}{4L}\), so \(l=2L\). Option (1).

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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The second overtone of an open organ pipe has the same frequency as the first overtone of a closed pipe L metre long. The length of the open pipe will be

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