2019-09-30|The Simplest Homopolar Motor

A free-standing homopolar motor comprises an AA battery, a disc-shaped rare-earth magnet and a copper wire. There are various approaches to achieve efficient rotation, but the simplest design (non-suspension) having the smallest number of components plus the number of bend points (changes in the angle of curvature) will win.

The High-Efficiency Self-Regulating Asymmetrical Homopolar Motor has been further improved to achieve ultimate simplicity with a copper wire bent at only 1 location, yet maintaining careful balance. The rotor is now symmetrical, carrying current from the top of the battery to the bottom of the battery in 2 branches in a loop, doubling the force perpendicular both to the magnetic field and to the direction of the current flow according to Fleming's left-hand rule for motors. As the motor rotates, the copper wire's loop touches only one side of the disc-shaped rare-earth magnet intermittently, forming self-regulating pulse current to cause the rotor to reach steady-state terminal angular velocity instead of uncontrolled acceleration to make the rotor fly away as seen in many YouTube videos. Since the current flow in the circuit is not continuous, power consumption is low enough to keep the rotation going and going and going like the Energizer Bunny.
- (the number of components: 3) + (the number of bend points: 1) = total: 4

A homopolar motor comprises an AA battery, a disc-shaped rare-earth magnet and a copper wire. Googling "homopolar motor" reveals numerous creations, some sophisticated and artistic like a heart-shaped rotor. Here is what I claim to be absolutely the simplest design with a copper wire bent at only 2 locations to achieve careful balance. The rotor is asymmetrical with a horizontal straight line which maximises the force perpendicular both to the magnetic field and to the direction of the current flow according to Fleming's left-hand rule for motors. As the motor rotates, the copper wire's horizontal straight line touches only one side of the disc-shaped rare-earth magnet intermittently, forming self-regulating pulse current to cause the rotor to reach steady-state terminal angular velocity instead of uncontrolled acceleration to make the rotor fly away as seen in many YouTube videos.
- (the number of components: 4) + (the number of bend points: 2) = total: 6

Here is an overhead view of "Ultra-High-Efficiency Self-Regulating Symmetrical Homopolar Motor with a Circular Rotor" (First prize with 1 bend point) and "High-Efficiency Self-Regulating Asymmetrical Homopolar Motor" (Second prize with 2 bend points) dancing together in unison on a flat platform and on a 3-Dimensional chess style platform.