Here's an interesting "push-pull magnet you can play with. This magnet both attracts and repels another magnet depending on how close it is to theother magnet. The "push-pull" magnet is constructed by stacking together four or more ceramic disk magnets like the ones you can get at the craft store. (See Fig. 1) The magnets colored green all pointing the same direction, with the repelling pole pointed toward the magnet that's hanging from the little swing. (I made my swing out of heavy cardboard backing from a writing tablet)
The red colored magnet is turned to face opposite from all the others inthe stack., so that it alone attracts the swinging magnet. It will have to be held in place to prevent it from flying away from the rest of the stack. I used masking tape for that.
Fig. 1
Now as you push the stack of magnets closer to the hanging magnet you can see how strongly it is repelled by the stack. But when the stack getsclose enough, suddenly the swinging magnet is attracted to the stack. Once you have the swinging magnet stuck to the cardboard stop labeled "A" (which prevents the swinging magnet from touching the "push-pull" magnet) you canslowly pull the stack away. Using 4 magnets in the stack (3/4 inch diam ceramic "craft" magnets, with the red one turned in reverse) when the stack is about 10 or 12 millimeters from the stop the swinging magnet willno longer be attracted, but will suddenly be repelled and will swing awaywith considerable force.
Moving the stack closer again the swinging magnet can be pushed closer tothe stack. Again at 10 to 12 mm away it will suddenly stop being repelledand will be attracted to the stack.
The whole setup can be made with cardboard and white glue. The dimension of the swinging part is shown in Fig. 2. Other parts are scaledaccordingly. The crossbar part of the T-shaped swing sets into V-shaped grooves in the tops of the side supports. Two of the magnets can be attached to the swing by simply putting one on each side of the cardboard strip and letting their mutual attraction hold them there. Or they can also be white-glued to the swing.
Fig. 2.
Using more magnets in the stack (still keeping only one reversed) will resultin a larger repulsive force, but a smaller region of attraction. Fewermagnets will result in weaker repulsion, and a much larger area where attractiveforces predominate.
Food For Thought
Now since it can be shown that there is a region of zero force near the poleof the magnet it should be possible to arrange a way for one magnet to beslid into place very close to the stack, staying always at the zero-forcedistance. Then, if the movable magnet were to be pushed slightly awayfrom the stack it would experience an area of increasing repulsion and thatforce might be used to supply energy to an over-unity motor.
Fig. 3. Force vs distance
emial the original author of this sections
Check out the floating metal bar and a simple experiment that floats a metal disk above a permanent magnet field this web master discovered by accident and detials is at my website page. Floating disk demostration location
This and a another floating bar and magnet design that has beeen around since the 1930's.These details can be found at my website at Floating bar demostration location
This motor was first built and constructed in the 1870's and was reported in Harpers New Monthly magazine magazine March 1879 The following website has the best explanation I have seen yet.
Canadian Patent 10,239 By Gary W. Wesley.
