Dielectric Constant

Dielectric Constant is the ratio of the capacity of a condenser made with a particular dielectric to the capacity of the same condenser with air as the dielectric. For a plastic used to support and insulate components of an electrical network from each other and ground, generally it is desirable to have a low level of dielectric constant. For a material to function as the dielectric of a capacitor, on the other hand, it is desirable to have a high value of dielectric constant, so the capacitor may be physically as small as possible. ASTM D-150.