What role does a relay perform in an electrical circuit?

A relay functions as an electrically operated switch, allowing control over a circuit without a direct mechanical connection. When a small current flows through the relay coil, it generates a magnetic field that opens or closes contacts in the circuit, enabling or disabling the flow of a larger current. This mechanism allows relays to manage power to devices or circuits that require more current than what the controlling circuit can handle.

By using relays, you can isolate different parts of a system, control high-voltage devices with low-voltage signals, and provide safety features in electrical designs. This is particularly useful in applications where remote operation or automation is required, allowing a small control signal to influence larger loads efficiently.

The other options present different electrical components or concepts that do not accurately describe the role of a relay. For instance, allowing current to flow in multiple directions pertains to diodes or specific circuit configurations, while energy storage is associated with capacitors. Changing voltage levels is typically the function of transformers or DC-DC converters, rather than relays.