The difference in frequencies of the first overtones of the open organ pipe and closed organ pipe is 2.2 Hz. Write the frequencies in terms of length of the pipes and get the relation between the lengths of the pipes. The fundamental frequency of the closed organ pipe is given so its length can be easily found.
The **** are produced when the wave of same amplitude but different frequencies, resonate with each other.
Let the length of open and closed pipes be l1 and l2 , respectively.
The frequency of first over tone of open organ pipe is
n1 = 2v/2I1 = v/I1
The frequency of first over tone of closed organ pipe is
n2 = 3v/4I
Fundamental frequency of closed organ pipe