Question

Velocity of sound in air is $320m/s$. A pipe closed at one end has a length of $1m$. Neglecting end correction, the air column in the pipe can resonate for the sound of frequency :

• A. $80Hz$
• B. $240Hz$
• C. $320Hz$
• D. $400Hz$

Answer 1

Answer: (A), (B), (D)

The correct options are
A $80Hz$
B $240Hz$
D $400Hz$

$f=(n=\frac{1}{2})\frac{V}{2l}\Rightarrow (n+\frac{1}{2})\frac{320}{2\times 1}$

Now,

1. 80 $=(n+\frac{1}{2})160\Rightarrow n=0$

2. 240 $=(n+\frac{1}{2})160\Rightarrow n=1$

3. 400 $=(n+\frac{1}{2})160\Rightarrow n=2$