Question

An open pipe of length 33 cm resonates with frequency of 1000 Hz. If the speed of sound s 330 $m{s}^{-1}$, then this frequency is

• A. The fundamental frequency of the pipe'
• B. The first harmonic of the pipe
• C. The second harmonic of the pipe
• D. The forth harmonic of the pipe

Answer 1

The correct option is C The second harmonic of the pipe

Fundamental frequency (first harmonic frequency) of an open organ pipe is given by ,

$n_1=v/\lambda =v/2l$ ,

where $v=$speed of sound in air ($=330m/s,given$),

$\lambda =$ wavelength ,

$l=$ length of organ pipe ($=33cm=0.33m$ , given) ,

therefore , $n_1=330/(2\times 0.33)=500Hz$ ,

as an open pipe produces even and odd harmonics , and given frequency is 1000Hz , it is 2 times of the first harmonic frequency , therefore it is second harmonic frequency of the pipe .