An electromagnetic relay is a type of electrical switch controlled by an electromagnet.
It is used in a variety of applications, including alarms and sensors, signal switching, and the detection and control of faults on electrical distribution lines.
Electromagnetic relays operate on the principle of electromagnetic attraction.
They use a magnet to create a magnetic field, which is then used to open and close the switch and perform the mechanical operation.
Relays are usually used in automatic control circuits.