Question

A vibrating tuning fork is placed over the mouth of a burette filled with water. The tap of the burette is opened and the water level gradually starts falling. It is found that the sound from the tuning fork becomes very loud for a particular length of the water column.
(i) Name the phenomenon taking place when this happens.
(ii) Why does the sound become very loud for this length of the water column?

Answer 1

Explanation for the part $\left(i\right)$:

1. The frequency of the vibrating tuning fork becomes equal to the frequency of the vibrating air column as a result the amplitude of the sound produced is increased.
2. The phenomenon taking place is called resonance.

Explanation for the part $\left(ii\right)$:

1. The loudness of sound is proportional to the square of the amplitude.
   $I\propto a^2$
   Where, $I$ is the intensity of sound, $a$ is the amplitude.
2. Since the loudness is proportional to the square of the amplitude, so the sound is the loudest.