Dielectric in Capacitor


A capacitor is an electronic component that temporarily holds charge. The stored charges can work while flowing again. Compared to the flow of a river, a capacitor can be likened to a dam that holds a river.

The capacitor is made by making two thin metal plates close together but not touching each other. For this reason, the symbol of the capacitor is drawn as if the two metal plates came close to each other.

When a voltage is applied to the facing electrode, charges are accumulated on the electrode. The reason that the charges do not escape to another place is that the attraction forces acts between the charges with different polarities.

How to increase capacity of capacitors

Let’s see how to increase the capacity of the capacitor. First of all, it is easy to imagine that the wider the capacitor, the larger the capacity.

The narrower the gap between the electrodes, the stronger the attraction of the charges, so that the charges can be held well. Therefore, the capacitance of the capacitor is inversely proportional to the distance between the electrodes.

Putting the dielectric between the capacitor electrodes increases the capacity of the capacitor. A dielectric is a material in which charge bias occurs inside a material. As the charge is held by the dielectric polarization, the capacity of the capacitor increases.

Dielectric and Permittivity

All materials are polarized inside in response to external electric fields. The degree of response to an electric field is called “Permittivity”. Permittivity is slightly different for each substance. Higher dielectric can storage more charge even the same amount of material.