A relay is an electrically operated switch that allows a low-power control circuit to manage the switching of a higher-power circuit. It consists of an electromagnet, a set of contacts, and a spring mechanism. When an electric current passes through the electromagnet coil, it creates a magnetic field that causes the contacts to either open or close, depending on the design of the relay. This action allows the relay to control a separate circuit without a direct physical connection between the low-power control side and the high-power side.

    Relay circuits are often used in situations where it is necessary to control large currents or voltages with a smaller, less expensive control circuit. This makes them indispensable in a wide variety of electrical systems, from home appliances to industrial machinery.