William Sturgeon’s electromagnet invention opens a new era of electricity

Story: 1824 C.E.  |  Last updated: January 1, 1824

In 1824 C.E., a British instrument maker with no university degree and a background in the army demonstrated something that no one had ever managed before: a magnet you could switch on and off. William Sturgeon bent a piece of iron into a horseshoe, wrapped it in bare copper wire, and sent a current through the coil. The iron came alive, lifting nine pounds of weight — then dropped everything the moment the current stopped. The electromagnet had arrived.

Key findings

• Electromagnet invention: Sturgeon’s 1824 C.E. device consisted of a horseshoe-shaped iron core wrapped with roughly 18 turns of bare copper wire, varnished to prevent short-circuits — because insulated wire did not yet exist.
• Magnetic force: The device weighed only seven ounces but could lift nine pounds when connected to a single-cell power supply, demonstrating that electric current could create a concentrated, controllable magnetic field.
• Scientific foundations: Sturgeon’s work built directly on Hans Christian Ørsted’s 1820 C.E. discovery that electric currents produce magnetic fields, and André-Marie Ampère’s demonstration that iron could be magnetized inside a current-carrying coil.

What Sturgeon actually built — and why it worked

The physics behind the electromagnet is elegant. When electric current flows through a coil of wire, it generates a magnetic field along the coil’s central axis. Place a soft iron core inside that coil, and the effect multiplies dramatically. Iron is made up of microscopic regions called magnetic domains — tiny regions where atoms act like miniature magnets. Normally these domains point in random directions, canceling each other out. When current flows through the surrounding coil, those domains snap into alignment, and the iron’s field merges with the coil’s, creating something far stronger than either alone.

Sturgeon understood this intuitively, even without the theoretical framework that would come later. He varnished his iron core to insulate it from the uninsulated copper wire — a practical solution to a practical problem. His device was modest by later standards, but the principle was proven.

The core concept Sturgeon demonstrated — that magnetism could be created, strengthened, and extinguished on demand — was unlike anything a permanent magnet could offer. Permanent magnets are always on. Sturgeon’s device gave engineers a tool they could control.

Joseph Henry and the leap forward

Within six years, the electromagnet invention had crossed the Atlantic. Beginning in 1830 C.E., American scientist Joseph Henry systematically refined Sturgeon’s design. His key insight was to use silk-insulated wire, which allowed multiple layers to be wound tightly around the core rather than a single spaced-out layer. More turns meant a stronger field. Henry eventually built an electromagnet capable of supporting 2,063 pounds — nearly a ton — from a device that fit on a workbench.

Henry’s work drew on an earlier technique developed by Johann Schweigger, a German physicist who had wound multiple wire coils around a compass needle to build a sensitive current detector called a galvanometer. The electromagnet’s story, like most breakthroughs, is a story of accumulated ideas crossing borders and disciplines.

The Smithsonian’s history of electrical science traces how these compounding discoveries — Ørsted, Ampère, Sturgeon, Henry — formed a chain that made the electrical age possible.

Lasting impact

It is difficult to overstate how much of modern life depends on the controlled magnetism Sturgeon first demonstrated. The telegraph, which shrank the world in the mid-19th century, relied on electromagnetic sounders to convert electrical pulses into audible clicks. Electric motors — which power everything from factory machines to electric vehicles — work by using electromagnets to create rotational force. Generators reverse the process, converting motion into electricity.

The list extends into medicine. MRI machines use superconducting electromagnets to generate the precise magnetic fields needed to image soft tissue inside the human body without radiation. Hard drives store data using tiny electromagnetic read-write heads. Loudspeakers translate electrical signals into sound through electromagnets pushing a cone back and forth.

Even the Institute of Electrical and Electronics Engineers, one of the world’s largest professional organizations, traces its origins to the era of discovery that Sturgeon’s electromagnet helped launch. The technology rippled outward for two centuries and shows no sign of stopping.

The magnetic domain theory that explains why iron cores work so well wasn’t formally proposed until 1906 C.E., when French physicist Pierre-Ernest Weiss introduced the concept. The full quantum mechanical account came in the 1920s C.E., through the work of Werner Heisenberg, Lev Landau, Felix Bloch, and others. Sturgeon built something that worked long before anyone could fully explain why.

Blindspots and limits

Sturgeon’s original electromagnet was underpowered by any later standard — his uninsulated wire forced him to space out the turns, sharply limiting the field strength he could achieve. The 1824 C.E. invention also came entirely within a European scientific tradition that had access to stable electrical cells, workshop tools, and a network of scientific communication through institutions like the Royal Society; it is worth asking what parallel knowledge about magnetic materials existed in other traditions — in China, India, or among Indigenous communities who worked extensively with iron — and why those traditions are rarely part of the canonical history. Sturgeon himself received little recognition in his lifetime and died in poverty in 1850 C.E., a reminder that the people who open new eras are not always the ones who benefit from them.

Read more

For more on this story, see: Wikipedia — Electromagnet

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