Correct Answer - a
Wavelenght of closed prgan pipe is ,`lambda = (4l)/((2n-1))`
Putting `n=1,2,3...` we find that `lambda _(1) =4L, (4L)/3, (4L)/5, ...`
So, frequency of vibration corresopending to modes
`n=1,2,3,... `is
`v_(1) = v/lambda_(1) = v/(4L)=v_(1) `
`v_(2)= v/lambda_(2)=v/(4L//3) = (3v)/(3L) = 3 v_(1)`
`v_(3) = v/lambda_(3)=v/(4L//5) = (5v)/(4L)= 5 v_(1)`
`therefore v_(1): v_(2) : v_(3) ....... = 1 : 3 : 5 : ...`
So, only odd harmonics are present.
