Experiments with magnets interacting with other magnets
This is a great demonstration of like poles repelling each other. We have a platform which floats above a pair of magnetic tracks, and can be gently pushed to one end or the other. This is similar in concept to the MAGLEV trains which are being worked on in Germany, Japan and France.
The tracks are simply two magnet strips, each measuring about 24" long, 1/2" wide, 1/8" thick, with their North side facing up. They are placed about 1/8" in from the edges of a piece of 3/4" thick wood shelving (with a white melamine surface) base, 24" long and 4" wide. Ends and a back wall are attached to the base, about 3" tall. The front of the base has a Plexiglas wall attached to it, so that you can see the train platform float above the tracks.
The train platform is made of foam-core board, 3 and 7/8" wide by 6" long and 1/4" thick. On the bottom is a pair of magnet strips, about 6" long, 1/2" wide, 1/4" thick, with their North side facing down. They are placed about 1/8" in from the side edges.
Attached to the ends of the base and to the ends of the train platform are smaller disk ceramic magnets, placed so that the North ends face each other so that they act as springs when the train reaches the end of the track. An extra strip of foam-core board was added to the top and bottom to provide a larger area to attach the end magnets.
Along the side edges of the platform was placed a strip of Teflon tape. This provided a very smooth, slippery surface for the train to rub against as it travels down the track. The back wall and the Plexiglas front wall are needed to keep the platform centered above the tracks. What would happen if they weren't there?
The LEGO people were added as passengers for interest.
An excellent site for more in-depth information on MAGLEV trains:
Give the train platform a gentle push from one side to the other. You will see it float over the tracks. The magnets on the ends keep the platform from hitting the ends (don't smash it into the ends!).
This is just a fun experiment which demonstrates the like poles repelling principle of magnetics. There are four pairs of poles repelling each other on this train.
This is a simplified diagram showing the areas of attraction and repulsion between the magnets for this experiment.
The magnets we used for our experiment were from a kit put together by Dowling Magnets (Sonoma, CA) called Magnetic Levitation Set - SDK100.
Dowling Magnets Catalog (http://www.jalts.com/nature/dowling).
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They provided the two long magnet strips for the "tracks" as well as the two shorter pieces for the bottom of the platform. We mounted the tracks onto a piece of shelving, and used a piece of foam core board for the platform. This worked out better than the wooden pieces which came with the kit. Don't forget the sides to keep the platform centered above the tracks! This kit costs about $23, but it's possible to purchase only some of the strip magnets for a lot less from Dowling Magnets.
Since the foam core platform we used was so light, the magnets do not have to be real strong. With the ones that came in the kit, the bottom of the platform magnets float about 1/4" above the tracks.
Also available from Edmund 81-462, AS&S 89714