question_answer 17)

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 ends are open. Speed of sound = 340 m/s.

Answer:

Here, L = 20 cm = 0.2 m, v,, = 430 Hz, = 340 The frequency of nth normal mode of vibration of closed pipe is                                        Hence it will be the 1st normal mode of vibration.                                                    In a pipe, open at both ends, we have    As n has to be an integer, therefore, open organ pipe cannot be in resonance with the source,