Dielectric

Dielectrics in Parallel-Plate Capacitors

Putting a dielectric material between the plates in a parallel plate capacitor causes an increase the capacitance in proportion to k, the dielectric constant of the material:

Related Topics:
Capacitor - Capacitance

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::C = rac{k epsilon_0 A}{d}

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:where epsilon_0 is the permittivity of free space, A is the area covered by the capacitors, and d is the distance between the plates.

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This happens because an electric field polarizes the molecules of the dielectric, producing concentrations of charge on its surfaces that create an electric field opposed (antiparallel) to that of the capacitor. Thus, a given amount of charge produces a weaker field between the plates than it would without the dielectric, which reduces the electric potential. Considered in reverse, this argument means that, with a dielectric, a given electric potential causes the capacitor to accumulate a larger charge.

Related Topics:
Polarize - Antiparallel - Electric potential - Charge

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