The electric motor

In plain language

An electric motor turns electricity into turning movement. Its basic trick is that a wire carrying a current, sitting near a magnet, is pushed sideways. If the wire is arranged so that the push keeps going round, the motor keeps turning. In September 1821 Michael Faraday showed this at the Royal Institution in London, where a wire carrying current circled the pole of a magnet. He called the effect electromagnetic rotation.

Over the next century inventors turned this idea into machines that could drive tools, trains, cars and starters. Early motors used batteries and a switching part called a commutator to keep the push going in one direction. Today's electric cars use motors built around permanent magnets or alternating-current windings, and designers must balance cost, efficiency and the supply of rare earth metals.

Technical explanation

A motor works because a conductor carrying current in a magnetic field feels a force. Faraday's 1821 apparatus used a wire dipping into mercury around a magnet's pole, so the current produced continuous rotation. Thomas Davenport's US Patent No. 132, dated 15 February 1837 in its specification (Google Patents lists 25 February 1837), describes a battery feeding segmented copper plates that act as a commutator. Electromagnets on a rotating wheel had their polarity reversed as they passed fixed steel permanent magnets, so they were first attracted and then repelled, which kept the shaft turning.

Tesla's US Patent No. 382,279, filed on 30 November 1887 and granted on 1 May 1888, describes motors whose field poles are progressively shifted by alternating currents, with currents induced in closed armature coils. The patent does not use the words 'induction motor' or 'polyphase'. Later writers apply those labels, so linking it to modern induction motors is an interpretation. Induction motors need no permanent magnets, because current is induced in the rotor by the rotating magnetic field.

Permanent-magnet motors often use neodymium-iron-boron (NdFeB) magnets, a strong magnet that relies on rare earth elements. The IEA reports that growing demand for permanent magnets, particularly from EVs and wind power, boosts the need for magnet rare earths. A 2026 mini review reports that about 87% of EV motors worldwide use NdFeB-based magnets, and it states that torque density remains 15% to 25% lower than equivalent NdFeB machines, without a citation for that figure. The review cites a 2016 paper for its 2024 figures, so these figures are treated as unverified here.

What the evidence says

Each statement is typed by the strength of its evidence and linked to the source that supports it.

Demonstrated Shown in a published experiment, test or shipping product.

On 3 September 1821, Michael Faraday showed in the Royal Institution's basement laboratory that a wire carrying an electric current revolved around a magnet's pole, which he called electromagnetic rotation.

Sources: [1] · Apparatus and What rotated sections

US Patent No. 132, titled 'Improvement in propelling machinery by magnetism and electro-magnetism', is dated 15 February 1837 in its specification, with Google Patents listing 25 February 1837. It names Thomas Davenport of Brandon, Vermont.

Sources: [2] · Grant date and inventor fields · medium confidence

Davenport's motor used a battery feeding segmented copper plates that worked as a commutator. Electromagnets on a rotating wheel reversed polarity as their wires switched between copper and zinc contacts, so each was first attracted to a fixed steel permanent magnet and then repelled by it.

Sources: [2] · Description of apparatus (partly illegible OCR) · medium confidence

US Patent No. 382,279, 'Electro-Magnetic Motor', was filed on 30 November 1887 by Nikola Tesla and granted on 1 May 1888. Its claims cover motors whose field poles are progressively shifted by alternating currents, with currents induced in closed armature coils.

Sources: [4] · Filing and grant dates; claims 1 to 3

Tesla's patent does not use the terms 'induction motor' or 'polyphase', so calling it an induction-type design is an interpretation rather than the patent's own wording.

Sources: [4] · Full specification

Cadillac introduced the electric self-starter on its 1912 model. Kettering's Delco design used one motor for starting, ignition and lighting, and it switched from dry cells to a storage battery so the motor could recharge it when the engine ran.

Sources: [5] · Delco design and Cadillac sections · medium confidence

The IEA says growing demand for permanent magnets, particularly from EVs and wind power, boosts the need for magnet rare earths, and that supply concentration for rare earths remains a key vulnerability.

Sources: [6] · Magnet demand drivers and Concentration risk

Reported, unverified Stated by a company or team but not independently confirmed.

According to VTDigger, Davenport could not afford to apply in 1835. In the following December a fire at the US Patent Office destroyed his model and paperwork, and he reapplied in January 1837. The article does not state the year of the fire, which is inferred here as 1836.

Sources: [3] · Main narrative · medium confidence

A 2026 mini review reports that about 87% of EV motors worldwide use NdFeB-based magnets, containing 1 to 3 kg of rare earth materials per motor in 2024. The review states that torque density remains 15% to 25% lower than equivalent NdFeB machines, without a citation for that figure.

Sources: [7] · Section 1 (87% and 1 to 3 kg) and Section 2 (torque density) · low confidence

Limitations and open problems

Several 'first' claims are qualified. Davenport's patent is described as the first US patent for an electric motor, and VTDigger calls it the world's first patent for an electric motor, but the sources reviewed do not settle priority between countries or inventors.
Tesla's patent does not use the terms 'induction motor' or 'polyphase'. Describing it as an induction design is an interpretation.
Some details could not be checked against primary records. The Smithsonian's record and replacement model were not accessible, the date of Davenport's British patent was not given, and the year of the Patent Office fire is inferred from context in VTDigger's article.
The sources reviewed did not give a verified date for when permanent-magnet starter motors first replaced field-coil designs, so this profile does not date that change.
The figure that about 87% of EV motors use NdFeB magnets comes from a 2026 mini review that cites a 2016 paper for its 2024 figures, so it is treated as unverified.

Possible future uses

Speculative

Ideas, not predictions. None of these has been demonstrated.

Magnet-free or low-rare-earth traction motors for mass-market electric cars, if magnet prices and supply remain volatile.
Electric propulsion for electric aircraft and boats using permanent-magnet or reluctance machines.
Integrated motor-generator units that combine starting, charging and lighting in one machine, extending the Delco design to hybrid and electric vehicles.

Timeline

3 Sept 1821Michael Faraday shows a wire carrying current circling the pole of a magnet at the Royal Institution, calling the effect 'electromagnetic rotation'. Sources: [1]
Feb 1837US Patent No. 132 is granted to Thomas Davenport for propelling machinery by magnetism and electro-magnetism, using a battery-fed electromagnetic motor. Sources: [2], [3]
1 May 1888Tesla's US Patent No. 382,279, 'Electro-Magnetic Motor', is granted, describing motors with poles shifted by alternating currents. Sources: [4]
1912Cadillac introduces the electric self-starter on its 1912 model, a Delco design that used one motor for starting, ignition and lighting. Sources: [5]
21 May 2025The IEA's Global Critical Minerals Outlook 2025 identifies supply concentration for rare earths as a key vulnerability, and says growing demand for permanent magnets from EVs and wind power boosts the need for magnet rare earths. Sources: [6]

Glossary

Commutator: A rotating switch that reverses the current in a motor's coils so that the turning force keeps pushing in one direction.
Permanent magnet: A magnet that keeps its magnetism without an electric current, used in many modern motors.
Induction motor: A motor in which current is induced in the rotor by a rotating magnetic field, so the rotor needs no magnets or direct electrical connection.
NdFeB magnet: A neodymium-iron-boron permanent magnet with high strength, which relies on rare earth elements.

Sources

other
The birth of electric motion
Charlotte New. Royal Institution, 3 Sept 2021. Accessed 22 Oct 2026.
patent
Improvement in propelling machinery by magnetism and electro-magnetism (US Patent No. 132)
Thomas Davenport. Google Patents (USPTO full text), 25 Feb 1837. Accessed 22 Oct 2026.
news
Then Again: Fame eluded Brandon man who invented the electric motor
Mark Bushnell. VTDigger, 3 Jul 2022. Accessed 22 Oct 2026.
patent
Electro-Magnetic Motor (US Patent No. 382,279)
Nikola Tesla. Google Patents (USPTO full text), 1 May 1888. Accessed 22 Oct 2026.
other
Charles F. Kettering
IEEE Engineering and Technology History Wiki, Aug 2013. Accessed 22 Oct 2026.
government report
Global Critical Minerals Outlook 2025: Overview of outlook for key minerals
International Energy Agency, 21 May 2025. Accessed 22 Oct 2026.
review article
A review of structural design for reduced-rare-earth permanent magnet motors in new energy vehicles
Yingshuai Liu, Dongdong Li, Xintong Li. Frontiers in Mechanical Engineering, 23 Sept 2026. DOI: 10.3389/fmech.2026.1957624. Accessed 22 Oct 2026.

Revision history

3 changes since this profile was created.

Changes on 22 Oct 2026

Published on owner instruction (car lineage tech tree, 2026-10-22)165371a

Sources and claims re-checked against originals409337d

Initial profile drafted from primary sourceseaac9eb