What is the role of a relay in an electrical circuit?

The role of a relay in an electrical circuit is to control a high-power circuit using a low-power signal. A relay operates as an electrically operated switch that allows a small input current to control a larger output current. When the low-power signal is applied to the coil of the relay, it generates a magnetic field that activates the switch, closing or opening a circuit that handles higher voltages or currents. This is particularly useful in applications where it’s necessary to manage high-power devices from a safe distance or using minimal control power, thus protecting sensitive control components from high power.

Other roles, such as increasing voltage levels, prolonging the life of a circuit, or measuring current flow, do not reflect the primary function of a relay. Relays are not designed to boost or regulate voltages; instead, they act as intelligent switches. They also don't inherently contribute to the longevity of circuits nor measure current—these are tasks reserved for other components like transformers and ammeters, respectively.