Magnetic field
The area around a magnet or electromagnet where the effects of the magnetic force can be felt.
Magnetic flux
The number of magnetic lines of force set up in a magnetic circuit, measured in Webers (Wb).
Magnetic flux density
A measure of how compacted the lines of flux are, measured in teslas (T) or webers per square metre (Wb/m²).
Maxwell's screw rule
Describes the direction of the magnetic field produced by a current, using the analogy of driving a screw in the direction of current flow.
Solenoid
A coil wound into a tightly packed helix, producing a magnetic field when an electric current passes through it.
Electromagnet
A type of magnet where the magnetic field is produced by an electric current.
Relay
An electrically operated switch used to control a circuit with a low-power signal.
Contactor
A type of relay that can handle high power loads, used to directly control electric motors or other high-power devices.
Attraction
The force by which one object brings another closer.
Repulsion
The force by which one object pushes another away.