Question

A pipe 20 cm long is closed at one end. Which harmonic mode of the pipe is resonantly excited by a 430 Hz source? Will this source be in resonance with the pipe if both the ends are open? 

Answer 1

Length of pipe = L = 20cm = 0.2m 

Frequency of n^th node = υ_n = 430 Hz 

Velocity of sound = v = 340m|s 

Now, υ_n of closed pipe is :→ 

Hence, it will be the first normal mode of vibration, In a pipe, open at both ends we, have

As n has to be an integer, open organ pipe cannot be in resonance with the source.