ABSTRACT
In this chapter, the authors re-examine capacitors and, in particular, the effect of an electric field on dielectrics. They introduce the dipole moment that occurs when an electric field distorts an atom, or molecule. In effect, the electron cloud moves away from the field, whereas the positively charged nucleus moves in the direction of the field. It is probably the most important from an engineering point of view. To guard against ionization in a capacitor, the people must ensure that the capacitor plates are as uniform as possible – any points on the plates will generate a large electric field. Large-value capacitors tend to use polar materials, or electrolytes. Anyone who has used electrolytic capacitors will know that they have to be connected the right way round. Thus, if the people incorrectly connect an electrolytic capacitor, a very large current flows, resulting in a large bang and clouds of vaporized electrolyte.
