Faraday’s Rotating Cup Experiment

One of the first electric motors. Originally conceived by Michael Faraday to confirm and demonstrate Oersted’s observation that a magnetic field exists in a spiral around a conductor.

A permanent magnet is placed vertically inside a container of mercury. A copper wire is suspended into the mercury from above. An electric current is passed through the wire and mercury, creating an electromagnetic field around the wire, which interacts with that of the permanent magnet, causing the wire to rotate around the magnet.
Unidentified, c. early 1830s