electroimanes

An electromagnet, or electroimán, is a magnet in which a magnetic field is produced by an electric current. It typically consists of a ferromagnetic core—often iron—surrounded by a coil of insulated copper wire. When the coil is energized with direct current, a controllable magnetic field is generated.

The strength of the field increases with the current and the number of turns, and is enhanced by using a magnetic core. Laminated or air‑gapped cores reduce energy losses from eddy currents. In a typical operator design, the field can be turned on or off by supplying or cutting power.

Most electromagnets are designed as solenoids. They can be optimized for different tasks: lifting heavy steel objects, acting as holding devices, or driving relays and actuators. Direct current yields a steady field suitable for hold and release; alternating current can be used for induction or to produce oscillating forces in certain devices.

Applications include industrial lifting and sorting, magnetic separation, relays, valves, and braking systems. High‑intensity electromagnets are used in magnetic resonance imaging, where superconducting coils create strong fields, though they require cryogenic cooling.

Limitations include continuous power consumption, heat generation, and potential loss of magnetization if the core is not kept energized. Design choices must address safety concerns, electromagnetic interference with nearby equipment, and structural forces from strong magnetic fields.

History notes: The concept emerged in the early 19th century. William Sturgeon built the first practical electromagnet in 1825, using a horseshoe-shaped iron core wrapped with wire. Its ability to lift objects demonstrated the principle and spurred rapid development in telegraphy and electromechanical devices.