Welcome to the capacitor guide!

The capacitor guide will guide you in the world of resistors. This site is designed as an educational reference, serving as a reliable source for all information related to capacitors. Currently this website is under development with the goal to be as good as a reference on capacitors as the Resistor Guide is on resistors.

What is a capacitor?

Capacitors are passive electrical components to store electric energy. In the past they were referred to as condenser. A capacitor is made from electrical conductors that are separated by an insulator. The insulating layer is called a dielectric. Although all capacitors share the same basic principle components, the material choice and configuration can vary widely. They are common elements in electrical circuits. A few examples are to allow only AC current and block DC current, or to smooth a power supply output.

A capacitor is able to store energy in an electrostatic field that is generated by a potential difference across the conductors. So when a conductor is subject to a voltage, one plate of the capacitor will collect positive charge while the other will be negatively charged. The ratio of this electric charge and the potential difference (voltage) is called the capacitance in farads. This is the main parameter to describe a capacitor. The capacitance is the largest when the distance between the conductors is small and the surface of the conductors large. Ideal capacitors are described solely with capacitance, but in the real world some limitations exist. For example, the conductors and lead wires cause parasitic inductance and resistance. The static electric field has a limit on the maximum strength, which is described by the breakdown voltage. The leaking current through the dielectric is called the leakage current.