An Homopolar Motor is the Simplest DC
Electric Motor, Invented by Michael Faraday in 1821.
The homopolar motor was the first ever device to produce
rotation from electromagnetism itself.
It was first built and demonstrated by
in 1821 at the
Royal Institution in London.
An homopolar motor has a
magnetic field along the axis of rotation and an electric current that at
some point is not parallel to the magnetic field. The name homopolar
refers to the absence of polarity change.
Faraday's greatest work was with electricity. In 1821, soon after the
Danish chemist, Hans Christian Orsted, discovered the phenomenon of
magnetism, Humphry Davy and William Hyde Wollaston tried but failed to
design an electric motor. Faraday, having discussed the problem with the
two men, went on to build two devices to produce what he called
electromagnetic rotation which is a continuous circular motion from the
circular magnetic force around a wire. A wire extending into a pool of
mercury with a magnet placed inside would rotate around the magnet if
charged with electricity by a chemical battery. This device is known as a
homopolar motor. These experiments and inventions form the foundation of
modern electromagnetic technology. Unwisely, Faraday published his results
without acknowledging his debt to Wollaston and Davy, and the resulting
controversy caused Faraday to withdraw from electromagnetic research for
The motors were constructed
using metal wire suspended in a cup of mercury. Stick up from the bottom
of the cup was a permanent magnet.
We are improving the Homopolar Motor Kit Store, it will
be back in few days.