What function does a relay serve in an electrical circuit?

A relay serves an important function as an electrically operated switch in an electrical circuit. Its primary purpose is to control a high-power circuit with a low-power signal, allowing a small input current to switch on or off a larger load. When an electrical current passes through the coil of the relay, it creates a magnetic field that moves an armature, either opening or closing a set of contacts, thereby controlling the flow of current in the connected circuit.

This capability is essential for many applications, such as in automation, where relays can be used to control large machinery with smaller controls or in situations where isolation between different parts of a circuit is required. Using a relay ensures that the control circuit is separated from the high-power circuit, enhancing safety and protecting sensitive components from possible damage caused by high voltages or currents.

The other options suggest functions that a relay does not perform. It does not inherently modify voltage levels or increase current capacity; these tasks are typically handled by transformers and power management devices, respectively. While relays can contribute to maintaining stability in power supply indirectly, that is not their primary function, which is more accurately described as acting as a switch.