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

The purpose of a relay in an electrical circuit is to control a high-power circuit using a low-power signal. This is accomplished by utilizing an electromagnetic coil to operate a set of contacts. When a small current flows through the coil, it generates a magnetic field that closes or opens the contacts, allowing a separate high-power circuit to be switched on or off without direct electrical connection. This ability to control large loads while using a relatively small input signal is what makes relays essential in various applications, including automation systems and motor control.

The other options don't align with the primary function of a relay: increasing voltage pertains to transformers, insulation is handled by physical materials, and AC to DC conversion is the job of rectifiers. Understanding these distinctions is critical in electrical work, as it ensures proper application of components in circuits.