A pipe with 30 cm Length is open at both ends, which harmonic mode of the pipe resonates a 1.65 kHz source?…
A pipe with 30 cm Length is open at both ends, which harmonic mode of the pipe resonates a 1.65 kHz source? (Velocity of sound in air $=330 \mathrm{~ms}^{-1}$ )
$2$
$3$
$3.5$
$2.5$
Solution
For open organ pipe,
$\begin{aligned}
& \mathrm{l}=30 \mathrm{~cm}, \mathrm{f}=1.65 \mathrm{KHz} \\
& \therefore \mathrm{I}=\frac{\mathrm{n} \lambda}{2} \Rightarrow \mathrm{n}=\frac{21}{\frac{\mathrm{v}}{\mathrm{f}}}=\frac{2 \times 30 \times 10^{-2} \times 1.65 \times 10^3}{330} \\
& \therefore \mathrm{n}=3
\end{aligned}$