A dielectric can be placed between the plates of a capacitor to increase its capacitance. The dielectric strength E m is the maximum electric field magnitude the dielectric can withstand without breaking down and conducting. The dielectric constant K has no unit and is greater than or equal to one (K ≥ 1).
There is another benefit to using a dielectric in a capacitor. Depending on the material used, the capacitance is greater than that given by the equation C = εA d by a factor κ, called the dielectric constant. A parallel plate capacitor with a dielectric between its plates has a capacitance given by C = κε0A d(parallelplatecapacitorwithdielectric).
The insertion of a dielectric slab in a capacitor will polarise the charges. The polarisation of the charges on either side of the dielectric will produce an electric field in a direction opposite to the field produced by the source. The net electric flux will become zero, and this effect will result in an increase in capacitance.
capacitor: a device that stores electric charge capacitance: amount of charge stored per unit volt dielectric: an insulating material dielectric strength: the maximum electric field above which an insulating material begins to break down and conduct parallel plate capacitor: two identical conducting plates separated by a distance
This produces an electric field opposite to the direction of the imposed field, and thus the total electric field is somewhat reduced. Before introduction of the dielectric material, the energy stored in the capacitor was 1 2QV1 1 2 Q V 1. After introduction of the material, it is 1 2QV2 1 2 Q V 2, which is a little bit less.
Experimentally it was found that capacitance C increases when the space between the conductors is filled with dielectrics. To see how this happens, suppose a capacitor has a capacitance C when there is no material between the plates. When a dielectric material is is called the dielectric constant.