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

Answer

C

Explanation

`f_(1) = (2v)/(2L) = (v)/(L) rArr f_(2) = (nV)/(4L) rArr` As `(nV)/(4L) gt (v)/(L)`
`n gt 4 , n = 5`