In one metre long open pipe what is the harmonic of resonance obtained with a tuning fork of frequency 480 Hz

Options

A. First
B. Second
C. Third
D. Fourth

Answer

c

Explanation

For an open pipe of length l, the frequency n is given
by, `n=n'v/(2l)`

where, v is velocity of sound, n' the overtone.
Given, `n=480 Hz and l=1m and v= ms^(-1)`
`n' = (n(2l))/v=(480xx2xx1)/330=2.9approx 3`