An open pipe is in resonance in `2nd` harmonic with frequency `f_(1)`. Now one end of the tube is closed and frequency is increased to `f_(2)` such that the resonance again ocuurs in `nth` harmonic. Choose the correct option

Options

A. `n = 3, f_(2) = (3)/(4) f_(1)`
B. `n = 3, f_(2) = (5)/(4) f_(1)`
C. `n = 5, f_(2) = (3)/(4) f_(1)`
D. `n = 5, f_(2) = (3)/(4) f_(1)`

Answer

C

Explanation

`f_(1) = 2.(v)/(2l), f_(2) = n.(v)/(4l), n` is odd
`(f_(2))/(f_(1)) = (n)/(4)`
`f_(2) gt f_(1)` (given)
`n = 5, (f_(2))/(f_(1)) = (5)/(4) rArr f_(2) = (5)/(4) f_(1)`