Dielectric Materials - The Dielectric Constant

A common measure of the dielectric properties of a material is the dielectric constant. The dielectric constant can be defined as the tendency of a material to resist the flow of an electrical current across the material. The lower the value of the dielectric constant, the greater its resistance to the flow of an electrical current.

The standard used in measuring the dielectric constant is a vacuum, which is assigned the value of one. The dielectric constants of some other common materials are as follows: dry air (at one atmosphere of pressure): 1.0006; water: 80; glass: 4-7; wax: 2.25; amber: 2.65; mica: 2.5-7; benzene: 2.28; carbon tetrachloride: 2.24; and methyl alcohol: 33.1. Synthetic polymers are now widely used as dielectrics. The dielectric constants for these materials range from a low of about 1.3 for polyethylene and 2.0 for polytetrafluoroethylene (Teflon) to a high of about 7.2-8.4 for a melamine-formaldehyde resin.