Physics - Sound Wave Question with Solution | TestHub

The fundamental frequency of an open organ pipe is given by $n_o=\frac{v}{2L}=80$ Hz.

When one end of the pipe is closed, it becomes a closed organ pipe. Its fundamental frequency is $n_c=\frac{v}{4L}$.

Therefore, $n_c=\frac{n_o}{2}=\frac{80}{2}=40$ Hz.

A closed organ pipe produces only odd harmonics. The frequencies produced are $n_c,3n_c,5n_c,7n_c,\dots$

Substituting the value of $n_c$, the frequencies are $40,120,200,280,\dots$ Hz.

Answer: $40,120,200,280,\dots \dots \dots ..$.