Question

How many frequencies below $1\text{kHz}$ of natural oscillations of air column will be produced if a pipe of length $1\text{m}$ is closed at one end ? $\left[\text{velocity of sound in air is}340\text{m/s}\right]$

• A. 5
• B. 6
• C. 4
• D. 8

Answer 1

The correct option is A 5

For a closed organ pipe , length of air column will be ,

$L=\frac{\lambda }{4},\frac{3\lambda }{4},\frac{5\lambda }{4},\frac{7\lambda }{4}...$

and it is given, $V_S=340{\text{ms}}^{-1}$

$\nu =\frac{V_S}{\lambda }=85,255,425,595,833,\mathrm{1071...}$ below 1kHz there are 5 modes.

option A is correct.