ELECTRIC CIRCUIT

Animation of the movement of electrons (the opposite of conventional current) in a simple electric circuit consisting of a battery, a switch, and a light bulb.

ELECTRIC CURRENT is the flow of charge. Conventionally this is the flow of positive charge. However, in a simple circuit such as that illustrated the current in the wire is composed of electrons that flow from the negative pole of the battery (the cathode at the bottom of the battery) and return to the positive pole (the anode at the top of the battery, marked by a +).

The flow of electrons is opposite to the direction of the conventional current. The battery provides the electromotive force (or e.m.f.) that "pushes" the electrons through the wires of the circuit. Electromotive force is measured in volts. In some ways it is similar to the potential energy stored in an object at the top of a hill. The object might roll down the hill and lose its potential energy and, in an analogous way, the electrons flow down the voltage drop (or potential difference) as they traverse the circuit.