Question

A tuning fork vibrates at $250\text{Hz}$. Find the length of the shortest closed organ pipe that will resonate with the tuning fork.
[Speed of sound in air $=340\text{m/s}$]

• A. $33\text{cm}$
• B. $34\text{cm}$
• C. $35\text{cm}$
• D. $36\text{cm}$

Answer 1

The correct option is B $34\text{cm}$

For the shortest length, air in closed organ pipe vibrates in fundamental mode.
For closed organ pipe,
Fundamental frequency,
$f_o=\frac{v}{4l}$
$\Rightarrow 250=\frac{340}{4l}$
$\Rightarrow l=\frac{340}{4\times 250}=0.34\text{m}=34\text{cm}$