question_answer

An organ pipe is in resonance with a tuning fork. What change will have to be done in the length L to maintain the resonance, if (i) the temperature increases, (ii) hydrogen is filled in place of air and (iii) pressure becomes higher?

Answer:

                Suppose the organ pipe has both ends open. Then its fundamental frequency of vibration will be \[v=\frac{\upsilon }{2L}=\frac{1}{2L}\sqrt{\frac{\gamma P}{\rho }}\] (i) As the temperature increases, the velocity of sound increases, so to fix v constant, the value of L must be increased. (ii) If hydrogen is filled in the pipe in place of air, the value of density \[\rho \] decreases. To keep \[v\] constant, the value of L must be increased. (iii) The pressure has no effect on the velocity of sound. It does not affect resonance.