Velocity of sound in air is 320 $\text{ms}^{-1}$. A pipe closed at one end has length of 1 m. Neglecting end…

Velocity of sound in air is 320 $\text{ms}^{-1}$. A pipe closed at one end has length of 1 m. Neglecting end corrections, the air column in the pipe can resonate for sound of frequency
  1. 80 Hz
  2. 240 Hz
  3. 400 Hz
  4. All of these

Solution

Fundamental frequency of closed pipe, $f_1 = \frac{v}{4l} = 80\text{ Hz}$. Next is $f_2 = 3f_1 = 240\text{ Hz} \rightarrow \text{first overtone}$ and $f_3 = 5f_1 = 400\text{ Hz} \rightarrow \text{second overtone}$.

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