What is the function of a relay in electrical systems?

A relay serves as an electromechanical switch that allows a low-power signal to control a high-power circuit. This is achieved through the use of an electromagnetic coil that, when energized by the low-power signal, creates a magnetic field, causing a switch to close or open the high-power circuit. This function is crucial in various applications, enabling control over devices that require significantly more current than what a low-power signal can supply safely.

By allowing a small current to operate a relay, it can effectively control devices such as motors, lights, and other high-load equipment without subjecting the control circuit to the same high powers. This makes relays invaluable in automation and control systems where isolation and safety are key concerns.