Question

The number of possible oscillations of air column in a pipe closed at one end of length 85 cm whose frequencies lies below 1250 Hz are: (velocity of sound = 340 ms^–1 )

(A) 4 

(B) 5 

(C) 7 

(D) 6

Answer 1

Correct option: (D) 6

Explanation:

Fundamental freuency of a closed organ pipe is f1 = V / 4l = 340 / 4 x 0.85 = 100 Hz

The natural freuencies of the organ pipe will be f = 100 Hz, 300 Hz, 500 Hz, 700 Hz, 900 Hz, 1100 Hz which are below 1250 Hz