A circuit is a closed loop that allows electric charges to flow continuously from the positive terminal of a battery or other energy source, through external components, and back to the negative terminal. For a circuit to work, it must include an energy source that establishes a potential difference to drive the movement of charges along a conducting loop between the source's terminals. Common circuit components include batteries, wires, light bulbs, and resistors, with circuits classified as either series or parallel depending on how the components are connected.

1. Circuits March 30th, 2009