In an experiment with a closed organ pipe, it is filled with water by (1/5) th of its volume. ​

Question

In an experiment with a closed organ pipe, it is filled with water by \(\left(\frac{1}{5}\right) \)th of its volume. The frequency of the fundamental note will change by

(1) \(25 \%\)

(2) \(20\%\)

(3) \(-20\%\)

(4) \(-25\%\)

Answer 1

Correct option is : (1) \(25 \%\) 

\(f_0 = \frac{v}{4L}\)

When L is filled to \(\frac{1}{5}\)th of volume

Then new \(L = L- \frac{L}{5} = \frac{4L}{5}\)

then

\(f' = \frac{v}{4.4L/5}\)

\(= \frac{5}{4} \cdot \frac{v}{4L}\)

\(f' = 1.25 \ f_0\)

\(25 \%\) charge