Homopolar Motors
The homopolar motor is the simplest kind there is. With a minimal amount of materials you can amaze your friends.
Moving electric charges (an electric current) in a magnetic field experience a force that is perpendicular to both their direction of movement and the magnetic field, called the Lorentz force. In the homopolar motor shown on the below, the electric current produced by the battery moves radially through the disk magnet, which has a magnetic field along its longitudinal axis. The resulting Lorentz force in the tangential direction produces a torque in the magnet, which is free to rotate with the attached screw. http://en.wikipedia.org/wiki/Homopolar_motor
Type 1
This is a favorite for kids of all ages everywhere. It is simple and the materials are minimal and readily available.
Material List
A battery, It can be either an AA, a C or a D battery or a 9 Volt. I use rechargeable AA batteries and you should too. They are cheaper in the long run and they are GREEN.
6 inches of copper wire
A small Neodymium Magnets disk. For example I would try a 1/2" dia. by 1/4" thick disk, or a 5/8" dia. by 1/8" thick disk.
A steel flat head screw or suitable nail. A sheetrock screw works nicely.
Kids are absolutely amazed when they find out they can make a real working motor all by themselves. Great for "Show and Tell" even in kindergarten.
Nothing could be simpler. If you want to see it in action check out "Homopolar Motors" on "YouTube" where there are well over a hundred examples of this experiment.
Type 2
This is another simple version of the homopolar motor. Materials needed are an AA Battery, about a foot of copper wire and a cylinder or stack of cylinder NIBs.
The copper wire must be shaped something like the examples shown. Contact of the wire with the side of the Neodymium Magnet will cause it to spin. This is essentially a hands free motor, at least until it spins off the battery terminal. Again there are many many examples of this style in action on "YouTube".
Type 3
Last year I decided to make a unique version of the Homopolar Motor involving semi-levitation in a hands free design. I call it "My Multi-Axis Homopolar Motor". I'm rotating a cube as opposed to a cylinder because it is easier to see the rotation and it makes a neat little noise. The video shows it all. I am using a disposable battery here because the battery hold-down screw digs into the battery causing minor damage that I don't want on my rechargeable ones.
I wondered what would happen if I tried to make a homopolar motor using one of my big 2" dia by 1" thick NIBs. I modified one of my levitating frames leaving the lifting magnet, a 1/2" by 1/2" N50 cylinder, and the adjusting bolt. Lining up the magnet poles, I attached the 2" NIB to the 1/2" NIB using a 3 1/2" screw.
I got a YouTube comment about this video from Levinger1.
Impossible. pls shoot it again with something else near it, like a watch or anything else which not repeating its movement so we know for sure its not video trick, bcz it must be... Isn't against newton energy law or something?
I setup the experiment again, this time on an elevated glass platform with the requested time piece to prove that no camera tricks were involved in the video. I also recreated the experiment using a 2" by 2" by 1" thick NIB Block with a pull force of 325 pounds. I apologize about the lighting quality but it is a dismal rainy day today. Are you satisfied, Levinger1?