1. f/2 2. f 3. 3f/2 4. 2f

Answer: 2. f Key idea: an open pipe of length L has fundamental f=v/2L ; a pipe closed at one end of length l has fundamental v/4l . Dipping to half its length makes the pipe closed at the lower end with air column length l=L/2 : f'=v/4(L/2)=v/2L=f

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

A pipe open at both ends has a fundamental frequency f in air. The pipe is now dipped vertically in a water drum to half of its length. The fundamental frequency of the air column is now equal to :

1. $\frac{f}{2}$

2. $f$

3. $\frac{3f}{2}$

4. $2f$

Doubtly Asked 30 Oct 2026 NEET UG 2025 Practice test neet Save WhatsApp Report

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Answer: 2. $f$

Key idea: an open pipe of length $L$ has fundamental $f=\dfrac{v}{2L}$; a pipe closed at one end of length $l$ has fundamental $\dfrac{v}{4l}$.

Dipping to half its length makes the pipe closed at the lower end with air column length $l=L/2$:

$$f'=\frac{v}{4(L/2)}=\frac{v}{2L}=f$$

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

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A pipe open at both ends has a fundamental frequency f in air. The pipe is now dipped vertically in a water drum to half of its length. The fundamental frequency of the air column is now equal to :

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