A whistle whose air column is open at both ends has a fundamental frequency of $5100\text{ Hz}$. If the…
A whistle whose air column is open at both ends has a fundamental frequency of $5100\text{ Hz}$. If the speed of sound in air is $340\text{ ms}^{-1}$, the length of the whistle (in cm) is
5/3
10/3
5
20/3
Solution
For an open pipe, the frequency,
$f = \frac{v}{2l} \Rightarrow 5100 = \frac{340}{2 \times l}$
or $l = \frac{340}{5100 \times 2} \Rightarrow l = \frac{2}{30 \times 2} = \frac{1}{30}\text{ m}$
Therefore, $l = \frac{100}{30} = \frac{10}{3}\text{ cm}$