Relays are electrically operated switches that open and close the circuits by receiving electrical signals from outside sources. Relay works on the principle of electromagnetic induction. When the electromagnet is applied with some current, it induces a magnetic field around it. Relays are electric switches that use electromagnetism to convert small electrical stimuli into larger currents. These conversions occur when electrical inputs activate electromagnets to either form or break existing circuits. A relay is an electromechanical device, it can be used to establish an electrical connection. A relay is essentially a mechanical switch with the ability to be controlled electronically through an electromagnet, as opposed to being manually turned on or off. It consists of a flexible movable mechanical component.
Relays are used where it is necessary to control a circuit by a low-power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be controlled by one signal. A relay contains a coil, an armature, and at least one pair of contacts. Current flows through the coil, which functions as an electromagnet and generates a magnetic field. This pulls the armature, which is often shaped as a pivoting bracket that closes (or opens) the contacts. Relays are used where it is necessary to control a circuit by an independent low-power signal, or where several circuits must be controlled by one signal.
