The number of possible natural oscillation 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)
4
5
7
6
As learnt
Closed organ pipe -
A closed organ pipe is a cylindrical tube having an air colume with one end closed.
- wherein
Condition of constructive interference
f =
if n = 0 f0 = 100 Hz
n = 1 f1 = 300 Hz
n = 2 f2 = 500 Hz
n = 3 f3 = 700 Hz
n = 4 f4 = 900 Hz
n = 5 f5 = 1100 Hz
n = 6 f6 = 1300 Hz
Possible natural oscillation whose frequecies < 1250 Hz = 6 (n = 0, 1, 2, 3, 4, 5)
Option 1)
4
Incorrect
Option 2)
5
Incorrect
Option 3)
7
Incorrect
Option 4)
6
Correct