Physics - Sound Wave Question with Solution | TestHub

Fundamental frequency of closed pipe, $\begin{array}{l}n=\frac{V}{4L}=400\\ V=400\times 4L\end{array}$ If $\frac{1}{3}$ rd of pipe is filled with water, then remaining length of air column is $L-\frac{L}{3}=\frac{2L}{3}$. Now, fundamental frequency $=\frac{v}{4\left(\frac{2L}{3}\right)}=\frac{3v}{8L}$ The second harmonic of the pipe $=3\times$ fundamental frequency $\begin{array}{l}=3\times \left(\frac{3\mathrm{v}}{8\mathrm{L}}\right)\\ =3\times \frac{3\times 400\times 4\mathrm{L}}{8\mathrm{L}}\\ =1800\mathrm{Hz}\end{array}$