A pipe 20 cm long is closed at one end. Which harmonic mode of the pipe is resonantly excited by a source of 1237.5 Hz ? (sound velocity in air `=30ms^(-1))`

Explanation

Here, `l=12cm, v=1237.5Hz, upsilon=330m//s`
If nth harmonic of pipe resonates with the source, then `v=(2n-1)(upsilon)/(4l)`
`(2n-1)=(vxx4l)/(upsilon)=(1237.5(4xx20//100))/(330)=3`
`2n-1=3, :. n=2`