Gravity is Optional
Homopolar motors

A "normal" motor the magnetic fields (plural, produced by either physical- or electro-magnets) are arranged so that they point at right angles to the axis of rotation. In a homopolar motor, the magnetic field (singular) points along the axis of rotation.

A battery, a magnet, and a piece of wire is all you need to make these motors.

Until I have my own videos, enjoy these from youtube.

Normally, the centrifugal force tends to cause the rotating wire to fly away from the magnet. In this design, the wire near the top of the battery touches the shell on the opposite side of the electrical contact.

Homopolar Generator

If you drive the magnet, then you will create a homopolar generator which will produce DC current. As with the homopolar motor, the physics explaining how it works is a bit controversial. Basically, the phenomenon can not be explained using classical physics. In The Unipolar Generator: A Demonstration of Special Relativity, two professors at the University of Maryland explain how electrons traveling at different speeds in a constant magnetic field will undergo length contraction and produce charge separation - also known as a voltage.

That is an interesting paper, but I still think the jury is out.

From the Brown University physics department

Author: Robert Clemenzi
URL: http:// / Homopolar_motors.html