ABSTRACT
Any region in which an electric charge experiences a force is called an electrostatic field. Electric fields, Coulombs law, capacitance and permittivity are discussed in Chapter 6-refer back to page 55. Summarizing the main formulae:
Electric field strength, E= V d volts/metre
Capacitance C= Q V
farads
Electric flux density, D= Q A
coulombs/metre2
D E
D "0"r = "
Relative permittivity "r D flux density in materialflux density in vacuum The insulating medium separating charged surfaces is called a dielectric. Compared with conductors, dielectric materials have very high resistivities (and hence low conductance, since D 1/). They are therefore used to separate conductors at different potentials, such as capacitor plates or electric power lines.
