Question

A pipe of length `85cm` is closed from one end. Find the number of possible natural oscillations of air column in the pipe whose frequencies lie below `1250 Hz`. The velocity of sound in air is `34m//s`.
A. 6
B. 4
C. 12
D. 8

Answer 1

Correct Answer - A
Fundamental frequency of closed organ pipe
`f_(0)=(v)/(4l)=(340)/(4xx0.85)=100Hz`
So possible frequencies below 1250 Hz are
`100 Hz,300 Hz,500 Hz,700 Hz,900 Hz,1100 Hz`
`rArr` No. of frequencies = 6.