Increasing or decreasing pressure on a piezoelectric material causes electrical current to flow.	Electrical current flows in opposite directions depending on whether pressure is increasing or decreasing.
A piezoelectric lighter containing a ratchet mechanism, which cocks and strikes a piezoelectric crystal, produces a spark that travels several millimeters in air.	Magnified view of the spark produced by a piezoelectric lighter. Piezoelectric lighters are found in gas furnaces, ovens, driers, and barbeque grills.
Superimposed centers of positive and negative charge are represented by the two small dots in the middle of this array of ionic charges. When the crystal is compressed, the centers of positive and negative charge are displaced from one another, creating an electric potential	Motion caused by application of voltage to a hypothetical arrangment of ions. The center of the positive charge and the center of negative charge are shown by the smaller circles.
Application of a voltage to a piezoelectric device causes a small motion as can be seen in the movement of a reflected laser beam.

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