Question

An organ pipe with both ends open has a length $L=25\,cm$. An extra hole is created at position $\frac{L}{2}$, The lowest frequency of sound produced is
(Assume speed of sound $=340 \,m / s$ )

• A. $680\, Hz$
• B. $340\, Hz$
• C. $1360\, Hz$
• D. $4352 \,Hz$

Answer 1

Answer: (C)

We know that, there must be an antinode at the open end.
Since, a hole has been made at the position $\frac{L}{2}$,
so there must be another antinode at $x=\frac{L}{2}$

For lowest frequency, $\lambda=L=25 \,cm$
Frequency of sound produced,
$f=\frac{v}{\lambda}=\frac{340}{0.25}=1360 \,Hz$