Piezoelectric effect:

• When crystals like quartz or tourmaline are stressed along any pair of opposite faces, electric charges of opposite polarity are induced in the opposite faces perpendicular to the stress. This is known as piezoelectric effect.
• In other words the crystals which acquire a charge when compressed, twisted or twisted are said to be piezoelectric.
• The piezoelectric effect is shown in figure-

Piezoelectric Generator or Oscillator

Principle: Inverse piezoelectric effect

• If mechanical pressure is applied to one pair of opposite faces of certain crystals like quartz, equal and opposite electrical charges appear across its other faces. This is called as piezoelectric effect.
• The converse of piezoelectric effect is also true.
• If an electric field is applied to one pair of faces, the corresponding changes in the dimensions of the other pair of faces of the crystal are produced. This is known as ‘inverse piezoelectric effect’ or ‘electrostriction’.

Construction: