Polarization of Dielectric

This decreases the effective electric field between the plates and will increase the capacitance of the parallel plate structure. The dielectric must be a good electric insulator so as to minimize any DC leakage current through a capacitor. 这会降低板间的有效电场，并会增加平行板结构的电容。介电体必须是良好的电绝缘体，以最小化通过电容器的任何直流漏电流。

The presence of the dielectric decreases the electric field produced by a given charge density.

The factor k by which the effective field is decreased by the polarization of the dielectric is called the dielectric constant of the material.

Parallel Plate with Dielectric

The capacitance of a set of charged parallel plates is increased by the insertion of a dielectric material. The capacitance is inversely proportional to the electric field between the plates, and the presence of the dielectric reduces the effective electric field. The dielectric is characterized by a dielectric constant k, and the capacitance is multiplied by that factor.

Parallel Plate with Dielectric

When a dielectric is placed between charged plates, the polarization of the medium produces an electric field opposing the field of the charges on the plate. The dielectric constant k is defined to reflect the amount of reduction of effective electric field as shown below. The permittivity is a characteristic of space, and the relative permittivity or "dielectric constant" is a way to characterize the reduction in effective field because of the polarization of the dielectric. The capacitance of the parallel plate arrangement is increased by factor k. 当介电体放置在带电板之间时，介质的极化会产生一个反对板上电荷场的电场。介电常数k被定义为反映介质极化导致有效电场减少的程度，如下所示。电容率是空间的特性，而相对电容率或‘介电常数’是通过极化介电体导致有效场减少的方式来表征的。平行板装置的电容由因子k增加。 Table of dielectric constants 介电体常数表