The frequency of note produced in the p th mode of vibration in open pipe is vopen =2Lpv
The frequency of note produced in the pth mode of vibration in closed organ pipe is vclosed =4L(2p−1)v ∴ Ratio of pth mode of frequency of vibration of air in two pipes is vclosed vopen =(2p−1)v/4Lpv/2L=2p−12p