Q.
The fourth overtone of an open organ pipe has the same frequency as the second overtone of a close pipe of length L. The length of open pipe will be.
Fourth overtone of open is its fifth harmonic. f=5×2L0v f′=5×4Lv
(second over tone of close is its fifth harmonic)
given f′=f 2L05V=4L5V ∴2L0=4L L0=2L