Q. The number of possible natural oscillations of air column in a pipe closed at one end of length 85 cm whose frequencies lie below 1250 Hz are : (velocity of sound = 340 $ms^{-1}$)
A) 4
B) 5
C) 7
D) 6
Explanation
[Solution] $f = \frac{(2n-1)v}{4L} = (2n - 1) \times 100$ Hz: 100, 300, 500, 700, 900, 1100 Hz lie below 1250 Hz, i.e. 6. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.