property of all electrical nonconductors, or dielectrics, that manifests itself as a relatively slight change of shape, or mechanical deformation, under the application of an electric field. Reversal of the electric field does not reverse the direction of the deformation.

The converse piezoelectric effect occurs only in a particular class of nonconducting crystals and is characterized both by generally a much greater deformation for a given value of the electric field and by a reversal in the direction of deformation when the electric field is reversed. See piezoelectricity.