# Magnetic experiment

1. Feb 28, 2004

### juan avellaneda

Hi all
a few days ago a friend of mine show my this experiment, that i cant explain

he took a rectangular ceramic magnet dim 2" x 2" x 1" and put on a table with north polarity up, next he took a coin shape neodymium magnet with nort polarity down and begin to approach to the big . In the begining , there is a repulsion , but with a little push the coin magnet can be attached to the big

how is it possible, not we were saying, opposites atract and similars repel?

2. Feb 28, 2004

### chroot

Staff Emeritus
The magnetic fields caused by magnets shaped that way are not as simple as the basic bar magnet field you're used to seeing. I'd bet the magnets stuck together a little off-center, right?

- Warren

3. Feb 29, 2004

### juan avellaneda

not only that

and to finish my tale, i'll tell you that when you have the two magnets stucked, if you approach slowly a third magnet of similar power than ceramic, the coin magnet is released to a distance of at least 0.5 feets, like a catapult. Very interesting

4. Mar 1, 2004

### turin

How sure are you that the poles were axial? I had some AlNiCo disk magnets that had poles on the edge of the disk rather than one face N and the other S. Of course, that is not what I wanted, but I only found out about it when I saw how they stuck together.

5. Mar 1, 2004

### juan avellaneda

try it

the coin magnet can only be attached to a little region in the center of the ceramic magnet with dimension similar to the coin. Outside this region the magnet is strongly repeled and is impossible to do that.

why dont try it?Its easy to replicate

thks

6. Mar 1, 2004

### Integral

Staff Emeritus
Two different people have already told you what is happening, no one is doubting what you are seeing. The poles are not the two faces of the plate but the the center and the edge. turn your plate magnet over. What happens now? Should be the same as the other side. Flip you "coin" magnet over? What happens?

Try approaching the edge of the magnet with your "coin", what happens?

7. Mar 1, 2004

### juan avellaneda

turn magnet

when i turn big magnet the "coin" is attracted hardly over all the surface INCLUDING the edge. Does it agree with your idea?