TABLE OF CONTENTS Electrical circuits use insulator materials in various forms. Capacitors use dielectrics as a medium. The dielectric materials, which are also known as insulators, constitute a very important group of electrical (and electronic) engineering materials. They are characterized by a dielectric constant, dielectric loss, dielectric strength, and resistivity. The two properties namely, dielectric constant and dielectric loss, are strongly frequency dependent. The use of a dielectric in a specific application is dictated by the frequency of the applied voltage. The dielectric loss is required to be a minimum so that the performance of the dielectric does not deteriorate with time. Ferroelecrrics are ceramic dielectric materials which exhibit a very high dielectric constant and low dielectric loss. They are used in making miniature capacitors. Piezoelectrics are ferroelectric materials having very interesting properties. Mechanical deformation is produced in them in response to electrical force and electrical effects are produced in them in response to mechanical forces. The two piezoelectric effects are vastly exploited in all areas of technology. The dielectric loss manifests in the form of heat. The dielectric heating can be employed in cases where heating by other means is difficult or is not possible. It finds application in the fields such as food processing.
Materials such as glass, ceramics, polymers and paper are non-conducting materials. They prevent the flow of current through them. Therefore, they can be used for insulative purposes. When the main function of non-conducting materials is to provide electrical insulation, they are called insulators.
