What principle does a relay operate on?

A relay operates on the principle of electromagnetism to control a high-power circuit with a low-power signal. When a low-power electrical signal is applied to the coil of the relay, it creates a magnetic field. This magnetic field activates an armature that either opens or closes the contacts of the relay. Thus, a small input signal can manipulate a larger output circuit, allowing for the control of high-power devices without the need for the control signal to carry the same voltage or current.

This mechanism is particularly useful in various applications, including switching lights on and off, controlling motors, and interfacing with devices that run on high voltage or current. The ability to control high-power circuits safely and efficiently makes relays vital in electrical and electronic systems.