Capacitance allows for the storage of energy in an electrostatic field. Capacitance is present whenever two conductors are separated by an

insulator.

## PRINCIPLES OF CAPACITANCE

Capacitance is the ability of a device to store electrical energy in an electrostatic field. The symbol for capacitance is C. A capacitor is a device that possesses a specific amount of capacitance. A capacitor is made of two conductors separated by an insulator . The conductors are called plates and the insulator is called a dielectric.

## CAPACITORS

Four factors affect the capacitance of a capacitors:

- Area of the plate
- Distance between the plates
- Type of dielectric material
- Temperature

A capacitor is either fixed or variable. A fixed capacitor has a definite value that cannot be changed. A variable capacitor is one whose capacitance can be changed either by varying the space between plates (trimmer capacitor) or by varying the amount of meshing between two sets of plates (tuning capacitor).

## RC TIME CONSTANTS

An RC time constant reflects the relationship among time, resistance, and capacitance. The time it takes a capacitor to charge and discharge is directly proportional to the amount of the resistance and capacitance. The time constant reflects the time required for a capacitor to charge up to 63.2% of the applied voltage or to discharge down to 36.8%.