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 `=340ms^(-1)`).

Options

A. 4
B. 5
C. 7
D. 6

Answer

D

Explanation

`(lambda)/(4) = l = 0.85`
`lambda = 3.4`
Frequency of sound in this pipe
`v = (upsilon)/(lambda) = (340)/(3.4) = 100` Hz
Possible frequency in one side closed organ pipe.
= 1 : 3 : 5 : 7 : 9 : 11 : 13
100 Hz : 300 Hz : 500 Hz, 700 Hz : 900 Hz : 1100 Hz 1300 Hz
Only 6 frequencies are below 1250 Hz.