The history of electromagnets can be traced back to 1820, when Danish scientist Hans Christian Ørsted made the groundbreaking discovery that electric currents create magnetic fields. That same year, French scientist André-Marie Ampère demonstrated how iron could be magnetized by placing it within a solenoid that was energized by electricity. A few years later, in 1824, British scientist William Sturgeon invented the electromagnet. His initial design was a horseshoe-shaped piece of iron wrapped with approximately 18 turns of bare copper wire—the only type available at the time as insulated wire had not yet been developed. The iron was coated with varnish to insulate it from the wire windings. When electricity flowed through the coil, the iron became magnetized and could attract other iron pieces; the magnetism was lost once the current ceased. Despite its light weight of just seven ounces (about 200 grams), Sturgeon’s electromagnet could lift nine pounds (approximately 4 kilograms) with the current from a single-cell battery. However, the lack of insulation on the wire limited the design to a single spaced-out layer of windings, reducing the magnet’s strength. The electromagnet saw significant improvements starting in 1830 by American scientist Joseph Henry. He used wire insulated with silk, a method inspired by Schweigger’s galvanometer that incorporated multiple wire turns. This innovation allowed Henry to wrap several layers of wire around the cores, drastically increasing their power. One of his magnets, constructed with thousands of wire turns, was capable of supporting 2,063 pounds (936 kg). This marked the beginning of electromagnets’ widespread use, particularly in telegraph sounders.
