Question

An open organ pipe has a length of 5 cm. (a) Find the fundamental frequency of vibration of this pipe. (b) What is the highest harmonic of such a tube that is in the audible range ? Speed of sound in air is $340m{s}^{-1}$ and the audible range is 20-20,000 Hz.

Answer 1

(a)Here given,

$I=5cm=5\times {10}^{-2}m$

v=340 m/s

$\Rightarrow n=\frac{V}{2I}=\frac{340}{2\times 5\times {10}^{-2}}$

=3.4 kHz

(b)If the fundamental frequency =3.4 kHz

Then the highest Harmonic in the audible range (20 Hz -20 kHz)

$=\frac{20,000}{3400}=5.8=5$

(Integral multiple of 3.4 kHz)