Definitions and measurable quantities

It's a homogeneous insulating material that can contain and carry an electric field: in other words, it's a material that has no free charge carriers throughout its volume. An ideal example would be an absolute vacuum. But this situation – used in a few exceptional cases – is not generally suitable, and we have to resort to solid, liquid or gaseous materials, depending on the application. These materials are made up of atoms, molecules or ions bound together by electrical forces. Thus, the application of a high electric field will disrupt the very structure of the dielectric. In insulators, all electrons participate in the bonding of the structure (no free electrons in the conduction band, in contrast to conductive materials, where the presence of numerous free...