Question

An open pipe of length $33cm$ resonates to a frequency of $1000Hz$. The mode of vibration is $(\text{velocity of sound}=330m/s$)

• A. The $4^{th}$ harmonic
• B. The $2^{nd}$ harmonic
• C. The $3^{rd}$ harmonic
• D. Fundamental

Answer 1

The correct option is B The $2^{nd}$ harmonic

An open pipe length $l=33cm=0.33m$

velocity of sound $v=330m/s$

The fundamental frequency for open pipe ,$\lambda =2l$

$\Rightarrow n=\frac{v}{\lambda }=\frac{v}{2l}$

$\Rightarrow n=\frac{330}{2\times 0.33}$

$\Rightarrow n=500Hz$

In second harmonic frequency ,$n=\frac{v}{l}=\frac{330}{0.33}$

$\Rightarrow n=1000Hz$

Final answer : $\left(b\right)$