Piezoelectric Effect –

It is used for producing ultrasonic waves and is explained as –

When a quartz crystal is subjected to mechanical compression or tension across its faces than voltage having magnitude directly proportional to pressure is induced across the crystal. Its polarities are opposite for compression and tension. This phenomenon is called the direct piezoelectric effect. Conversely, if an a.c. voltage is applied across the crystal surface, it vibrates at the frequency of a.c voltage. This is called inverse piezoelectric effect.

The vibrator of max amplitude will occur at the resonance frequency of crystal.

The frequency is given by,

$F= \dfrac {n}{2L} \sqrt{\dfrac {Y}{\rho}} $