A tuning fork of frequency 340 Hz is sounded above a cylindrical tube 1 m long. Water is slowly poured into…
A tuning fork of frequency 340 Hz is sounded above a cylindrical tube 1 m long. Water is slowly poured into the tube. If the speed of sound is 340 $\text{ms}^{-1}$, at what levels of water in the tube will the sound of the tuning fork be appreciably intensified?
25 cm, 75 cm
20 cm, 80 cm
23 cm, 67 cm
40 cm, 80 cm
Solution
We have, $\lambda = \frac{v}{f} = 1\text{ m}$
$\frac{\lambda}{4} = 0.25\text{ m} = 25\text{ cm} \implies \frac{3\lambda}{4} = 0.75\text{ m} = 75\text{ cm}$
$\frac{5\lambda}{4} = 1.25\text{ m} = 125\text{ cm}$
These are the lengths of air column. Hence, lengths of water column will be $75\text{ cm}$ and $25\text{ cm}$.