What is the operational principle of a relay?

The operational principle of a relay involves using an electromagnetic coil to open or close contacts. When an electrical current flows through the coil, it generates a magnetic field that either attracts or repels an armature, which in turn opens or closes the switch contacts connected to the relay. This action allows the relay to control a larger electrical load with a smaller control signal, making it an essential component in various applications, including circuit control and automation systems.

Relays can effectively isolate different parts of a circuit and provide safety and reliability in switching operations, particularly when high voltages or currents are involved. This principle of using electromagnetic forces to operate mechanical contacts distinguishes relays from other devices like mechanical switches, which require physical movement of the switch itself, and amplifiers, which focus on increasing signal strength rather than controlling circuits.