Question

An open pipe is suddenly closed at one end with the result that the frequency of third harmonic of the closed pipe is found to be higher by `100 Hz` then the fundamental frequency of the open pipe. The fundamental frequency of the open pipe is
A. 200 Hz
B. 480 Hz
C. 240 Hz
D. 300 Hz

Answer 1

Correct Answer - a
Frequency of third harmonic of closed pipe, `n_(1)(3v)/(4l)`
Fundamental frequenccy of open pipe
`n_(2)=v/(2l)`
As `n_(1)-n_(2) = 100`
`rArr v/(4l)=100`
Fundamental frequency, `v/(2l)=200` Hz