Piezoelectricity

Piezoelectricity, pronounced pee ay zoh ih lehk TRIHS uh tee, is an electric phenomenon that occurs in certain nonmetallic minerals, such as quartz, Rochelle salt, and tourmaline. These crystals develop an electric charge on their surfaces when they are stretched or compressed along an axis. In addition, voltage applied to such crystals causes them to expand and contract, producing vibrations. Crystals that have these properties are called piezoelectric crystals. Pierre and Jacques Curie, two French physicists, published their discovery of piezoelectricity in 1880.

Piezoelectricity has many uses. Piezoelectric crystals control the frequency of electric current in radio transmitters. The crystals are cut so that only signals of a certain frequency can pass through them. Piezoelectric crystals in a phonograph pickup cartridge convert the vibrations of the phonograph needle into a varying electric signal. Piezoelectric crystals are also used in microphones and other electronic devices that change sound waves into electric signals.

Contributor: Thomas T. Liao, Ed.D., Prof. and Chairman, Department of Technology and Society, State Univ. of New York at Stony Brook.

Piezoelectricity

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