What is an electric current?
An electric current is the flow of electric charge, usually carried by electrons moving through a wire. It is measured in amperes, or amps.
In a metal wire, some electrons can move freely. When a voltage is applied, for example by a battery, it pushes these electrons along the wire, creating a current. The current flows in a complete loop called a circuit. If the circuit is broken, such as by switching off a light, the current stops.
Voltage is like the pressure pushing the charge, current is the amount of charge flowing and resistance is how much the material opposes the flow. These are linked by Ohm's law: voltage equals current times resistance. The electrons themselves drift slowly, but the electrical signal travels almost at the speed of light.
AC and DC
Direct current, or DC, flows in one direction, as from batteries. Alternating current, or AC, changes direction many times per second, 50 or 60 times depending on the country. AC is used for household power because it is easier to send over long distances.
Did You Know?
The unit ampere is named after French physicist André-Marie Ampère, a founder of the science of electromagnetism.