Ampère’s Law

Parallel wires carrying electric current generate magnetic fields, which in turn create magnetic forces between the currents. The relationship between electricity and magnetism was first observed by Hans Christian Ørsted, who discovered that a current-carrying wire could deflect a compass needle, providing the first evidence that electricity and magnetism are related. Following Ørsted’s discovery, André-Marie Ampère found that the magnetic fields produced by parallel current-carrying wires interact with one another. The force felt between two such wires is now used to define the ampere, the standard unit of electric current. Ampère also mathematically described the magnetic force between electric currents, leading to what is known as Ampère’s law. If the currents flow in the same direction, the wires are attracted to each other. If the currents flow in opposite directions, the wires are repelled from each other. Magnets that produce magnetic fields through electric current are called electromagnets. Electromagnets are widely used in various electrical devices.