Homopolar Motor

Here is a small challenge - to construct an electric motor from the parts shown above; a battery, a piece of wire, a screw and a neodymium magnet.

This simple electric motor was originally devised by a group of Japanese physics teachers who call themselves 'The Stray Cats'. The pieces assemble as shown in the photo - the magnet attaches to the head of the screw, and the pointed end of the screw attaches to the bottom of the battery. The neodymium magnet holds everything together. One end of the wire touches the terminal on the top of the battery; the other should touch the side of the neodymium magnet. This completes the electrical circuit, and means that a current flows through the magnet.

Since the magnet now has a current-carrying function, a Lorontz force acts tangentially to the inwardly flowing current in accordance with the right-hand rule, and the magnet spins.

Interestingly, this motor has many parallels with the first electric motors designed by Michael Faraday.

This simple motor has been around for a while. But we recently came across details of an amazing variation of this motor; it is called the Homopolar Roller....

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