Dielectric

The dielectric is the electric insulator which could be polarized by applying electric field.  When the dielectric is placed near the electric current or field, the electric charges do not flow via the material, like in the conductor, however only a small change or shift in from their average equilibrium positions which cause dielectric polarization.  Due to the dielectric polarization, the positive charges are shifted toward the field and the negative charges move towards the opposite direction that creates the internal electric field which partially balances the external field within or inside the dielectric.  If the dielectric has weakly bonded molecules, then not only those molecules become polarized but also reorient therefore their symmetry axis line up to the field.

Even though the word “insulator” refers to low electrical conduction, the dielectric is generally used to refer a material which has high polarizability.  Then it is expressed by a number which is known as the dielectric constant.  One of the common examples of the dielectric material is the electrically insulating element or material between the metallic places of the capacitor.  When the polarized dielectric material is applied with electric field, it increases the surface charge of the capacitor.  The study of the dielectric properties is related with the dissipation and storage of the magnetic and electric energy in the materials.  It is significant to explain about several phenomena in the optics, solid-state physics and electronics. William Whewell, an English scientist, polymath, Anglican priest, theologian, historian of science and philosopher, actually coined the term dielectric in response to the request from Michael Faraday.  Today most of the commercially manufactured capacitors are made from using solid dielectric material with high permittivity when the intervening medium between the stored negative and positive charges.

Questionnaire:

• What is dielectric? Explain.
• Who coined the term dielectric?