Engineering Physics

6.1 Introduction

Dielectrics are insulating materials. So, there are no free charge carriers in them. The dielectrics are of two types: (i) non-polar and (ii) polar dielectrics. In non-polar materials, the molecules are usually diatomic and composed of same type of atoms; each atom possesses a positive nucleus of charge q and surrounded by a symmetrically distributed negative electron cloud of charge –q. In the absence of an applied electric field, the centres of the positive and negative charge distribution coincide with each other. When external electric field is applied, then the centres of positive and negative charges move apart by a very small distance (10^–10 m), then the molecules and atoms are said to be polarized. Next, the polar dielectric ...