What is Dielectric Constant?
Dielectric constant is a measure or ratio of permittivity of a given dielectric substance to the permittivity of space. Permittivity pertains to the resistance or ability of a specific material to be polarized when forming an electric field. In physics, when the dielectric constant increases, electric flux density also increases. If this happens, objects like metal plates are able to hold electric charge in large quantities and for long periods of time. This is especially useful in the manufacture of high-value capacitors using material which are said to be high in dielectric constant. A material low in dielectric constant meanwhile has low permittivity and so has lesser ability for polarization and holding of electric charges.
Dielectric materials may be poor conductors of electricity but electrostatic fields are supported efficiently. Meaning energy can be stored by electrostatic fields when a particular current flow is kept to a minimum between two opposing electric poles, and when the electric flux is uninterrupted. This property is greatly helpful in radio frequency transmission lines.
Materials with high dielectric constant are not all good though. These materials actually break down more easily when compared with its low dielectric counterparts, especially if subjected to very intense electric fields. But materials with high-dielectric constant are still preferred for capacitors requiring a longer hold of the electric charge and for memory cells that store digital data. On the other hand, materials with low dielectric constant are said to be good insulators and used in instances where you need to isolate signal-carrying conductors from each other.
Dielectric materials used in practice are mostly solid, examples of which are ceramics, glass, plastics, and various metal oxides. But some liquids and gases are also good dielectric materials. Dry air is used mainly for capacitors and transmission lines. Distilled water is also considered a fair dielectric, and many agree that vacuum is very excellent to use.