# The number of possible natural oscillations of column in a pipe closed at one end of length 85 cm whose frequencies lie below 1250 Hz are : (velocity of sound = 340 ms1) Option 1) 4 Option 2) 5 Option 3) 7 Option 4) 6

As discussed in

$V_{n}= (2n+1)\frac{V}{4l}$

$n=0,\:\:V_{1}=100Hz\:\:\:\:\:\:\:\:\:\:\:\:\:\:n=3, \:\:V_{3}=700 Hz$

$n=1,\:\:V_{1}=300Hz\:\:\:\:\:\:\:\:\:\:\:\:\:\:n=4, \:\:V_{4}=900 Hz$

$n=2,\:\:V_{2}=500Hz\:\:\:\:\:\:\:\:\:\:\:\:\:\:n=6, \:\:V_{6}=1300 Hz$

i.e., Possible natural oscillation is 6.

Option 1)

4

This option is incorrect.

Option 2)

5

This option is incorrect.

Option 3)

7

This option is incorrect.

Option 4)

6

This option is correct.

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