When the frequency of an externally imposed periodic force on a body equals its natural frequency, the body begins to vibrate with greater amplitude. This phenomena is referred to as’resonance,’ and it is a type of forced vibration.
Install two identical tuning forks A and B on two different sound boxes with their open ends facing each other, as indicated in the diagram below.
When one of the tuning forks is struck on a rubber pad, prong A begins to vibrate. When you place this tuning fork A on its soundbox, the tuning fork B begins to vibrate as well, producing a loud sound. The vibrations in B are created as a result of the resonance.