This seemingly simple object was made by Michael Faraday in 1822. Its simplicity masks its true importance as the earliest surviving electric motor.
In 1820, Hans Christian Ørsted announced his discovery that the flow of an electric current through a wire produces a magnetic field around the wire. André-Marie Ampère went on and showed that the magnetic force was apparently circular, in fact producing a cylinder of magnetism around the wire. No such circular force had ever been observed before.
Self-taught British scientist Michael Faraday (1791 – 1867) was the first to understand what these discoveries entailed. If a magnetic pole could be isolated, it would constantly move in a circle around a current-carrying wire.
In 1821 Faraday set out to try to understand the work of Ørsted and Ampère, designing his own experiment using a small bath of mercury. This device, which transformed electrical energy into mechanical energy, was the first electric motor.
This device is the only surviving original example made by Faraday the following year after its discovery in 1822.
The motor features a stiff wire that hangs in a glass container that has a bar magnet attached to the bottom. The glass container would then be partly filled with mercury (a liquid metal at room temperature and an excellent conductor). Faraday connected his device to a battery, which sent electricity through the wire creating a magnetic field around it. This field interacted with the field around the magnet and caused the wire to spin clockwise.
This discovery led Faraday to contemplate the nature of electricity. Unlike his contemporaries, he was not convinced that electricity was a material fluid that flowed through wires like water through a pipe. Instead, he viewed it as a vibration or force that was somehow transmitted as a result of tensions created in the conductor.
Where can I see this?
This object is currently on display in Faraday’s original magnetic laboratory at the Faraday Museum.