CAPACITORS

 Capacitors

 Every system of electrical conductors possesses capacitance. For example, there is the capacitance between the conductors of overhead transmission lines and also between the wires of a telephone cable. In these examples, the capacitance is undesirable but has to be accepted, minimized, or compensated for. There are other situations where capacitance is a desirable property.

Devices specially constructed to possess capacitance are called capacitors (or condensers, as they used to be called). In its simplest form, a capacitor consists of two plates that are separated by an insulating material known as a dielectric. A capacitor has the ability to store a quantity of static electricity.

The symbols for a fixed capacitor and a variable capacitor are used in electrical circuit diagrams.

 The charge Q stored in a capacitor is given by:

 Q = I * t coulombs

where I is the current in amperes and t the time in seconds.