Physics · Sound Waves

NEET (UG) 2025 — Question 42

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 :

Option A:
$\frac{f}{2}$
Option B:
$f$
Correct
Option C:
$\frac{3 f}{2}$
Option D:
$2 f$

Answer: B

Step-by-step solution

For open pipe

$f=\frac{V}{2 \ell}$

When half of its length is dipped in water, Now it is COP.

$f^{\prime}=\frac{V}{4(\ell / 2)}$

$\mathrm{f}^{\prime}=\frac{\mathrm{V}}{2 \ell}$

$\mathrm{f}^{\prime}=\mathrm{f}$

Answer key and solution verified before publishing.

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Exam: NEET (UG) 2025
Paper: 2025 paper
Subject: Physics
Chapter: Sound Waves
Topic: Vibrations in rod and Air Columns - Organ pipes