What do relays, solenoids, and transformers rely on to function?

Relays, solenoids, and transformers all operate based on the principles of magnetism. In the case of relays, they use an electromagnetic coil to create a magnetic field that activates a switch, allowing current to flow through a circuit. Solenoids work by employing an electromagnetic coil to create linear motion, converting electrical energy into mechanical movement through the generation of a magnetic field. Transformers rely on magnetic induction to transfer electrical energy between circuits; an alternating current in the primary coil creates a changing magnetic field that induces voltage in the secondary coil.

While electricity is necessary to activate these devices, it is magnetism that is fundamentally responsible for their operation and functionality. Voltage fluctuations and mechanical pressure do not define their functionality in the same way; instead, these concepts are secondary to the magnetic principles at play. Therefore, the reliance on magnetism is central to understanding how these components work in electrical systems.