Capacitors and Capacitance

Capacitors and Capacitance

Capacitors and Capacitance

A capacitor is a device used to store separated electric charge and electrical energy.

A basic capacitor has two conductors separated by an insulating material.

Capacitance

Capacitance is:

**C = QV**

where:

0 = capacitance;

`Q` = magnitude of charge on either plate;

0 = potential difference.

Unit:

farad (F)

Parallel-Plate Capacitor

For parallel plates:

**C = εA/d**

Capacitance increases when:

plate area increases; permittivity increases.

Capacitance decreases when:

* plate separation increases.

Energy

Energy stored in a capacitor:

**U = ½CV²**

also:

**U = ½QV**

and:

**U = Q²2C**

Uses

camera flash circuits; smoothing power supplies; timing circuits; energy storage; * electronic devices.

Capacitors and Capacitance — Advanced