Electrostatic Induction

the induction of electric charges in conductors or dielectrics in a constant electric field.

In conductors, mobile charged particles (electrons) are moved by the action of an external electric field. The movement takes place until the charge is redistributed in such a way that the electric field generated by the charge within the conductor fully compensates the external electric field and the total electric field within the conductor becomes equal to zero. (If this did not occur, an electric current would exist for an infinite time within a conductor placed in a constant electric field, contradicting the law of conservation of energy.) As a result, induced charges of equal magnitude but opposite polarity develop in individual surface regions of the conductor, which is neutral as a whole.

Polarization occurs in dielectrics in a constant electric field; it consists either in a slight displacement of the positive and negative charges to opposite sides within the molecules, which results in the formation of electric dipoles (with an electric moment proportional to the external field), or in partial orientation in the direction of the field of molecules that have an electric moment. In both cases the electric dipole moment of a unit volume of the dielectric attains a nonzero value. Bound charges appear on the surface of the dielectric. If the polarization is nonuniform, bound charges also appear within the dielectric. A polarized dielectric generates an electrostatic field that is added to the external field.