What type of motor did Michael Faraday invent in 1821?

The type of motor Michael Faraday invented in 1821 was the homopolar motor. It was the first electrical motor to produce continuous rotary motion, demonstrating that electricity and magnetism could generate mechanical movement.

Faraday’s apparatus used a wire carrying current near a magnet immersed in mercury. The magnetic field exerted a force on the current-carrying wire, causing it to rotate continuously around the magnet. He called the phenomenon electromagnetic rotation; the term homopolar motor became common later.

A homopolar motor is a direct-current motor whose magnetic polarity remains constant, so it does not need a commutator to reverse current. That simplicity distinguishes it from many later practical motors, although homopolar designs are generally inefficient for everyday applications and require very high current.

The discovery followed Hans Christian Ørsted’s 1820 demonstration that electric currents affect magnets. Faraday’s 1821 experiment converted that interaction into motion and helped establish the foundation of modern electric-motor technology.