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  #1  
Old 03-21-2008, 01:17 AM
wolf_meister wolf_meister is offline
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Cutting a magnet in half.

If you take a typical magnet:

N           S

and cut it in half, the resulting magnets do not rejoin as you think they should and they actually repel.

You would think the resulting magnets would be like this:

N       S   N       S

However, if that were the case, the magnets would fit back together just as if the original hadn't been cut, but that is not what happens.

So, what are the polarities in the resulting 2 magnets?

Last edited by wolf_meister; 03-21-2008 at 01:17 AM..
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  #2  
Old 03-21-2008, 01:30 AM
Derleth Derleth is offline
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Cite? I'd never heard of this before, and I'd like some details.
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Old 03-21-2008, 02:01 AM
wolf_meister wolf_meister is offline
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Derleth
I do not have a cite. This is done from my own experience. I know it seems weird and just to make sure, I cut a magnet in two before I made that post just to make absolutely sure. I have always done this with ceramic magnets (easier to cut than metal) but I don't see how this would make that much of a difference.

Incidentally, I did search quite a bit on the Interent about this and (obviously) didn't find the answer. Every cite I did find says it happens just the way my diagram says it shoudn't work. I doubt I have made some earth-shattering scientific discovery but it's funny that I can't find anything on this rather weird phenomenon.

For anyone else that is not aware of this, please slice a ceramic magnet in two and see. Yes, I am always very careful to see that I am not flipping or rotating the resulting magnets. For example, for the one I just cut, I drew a line in pen in the middle of the magent. In this way, if one magnet is flipped or rotated, the line would not match up.
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Old 03-21-2008, 02:26 AM
Nametag Nametag is online now
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Are you sure you're not cutting along the axis?
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Old 03-21-2008, 02:33 AM
wolf_meister wolf_meister is offline
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Nametag
By that do you mean (referring to my N           S diagram), am I cutting it on a vertical and not a horizontal axis? I am cutting it on the vertical axis.
Perhaps someone should get a ceramic magnet and discover this for themselves.
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Old 03-21-2008, 02:49 AM
Saltire Saltire is offline
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I think Nametag may be on to something.

I'm not sure there's a way to determine where the poles are with a single magnet by itself. Poles are about how two magnets interact. Try checking how the original works with another magnet. Mark each end, of course. Then cut one magnet and check how each new piece works against the unaltered magnet.

If you cut a magnet through the poles, rather than between them, you'd see what you're seeing. Rather than:
Code:
N                N
   cut to give   S
                 N
S                S
You might have:
Code:
N  cut to give  N N
S               S S
So the like poles are near one another, and you get repulsion.
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Old 03-21-2008, 03:40 AM
wolf_meister wolf_meister is offline
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The only magnets I've ever seen polarized along the edges instead of the ends are guitar pickup magnets. And why? Because the magnetic strength is constant across all 6 strings, otherwise the middle strings would have a serious loss of voulme. Anyway, I have sliced through a lot of ceramic magnets and I find it strange why they would be magnetized along the edges whereas most magnets (the grade school N S type) are magnetized at the ends.
It's late I've got to get some sleep.

Last edited by wolf_meister; 03-21-2008 at 03:41 AM..
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Old 03-21-2008, 05:26 AM
Harmonious Discord Harmonious Discord is offline
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The only thing that makes since is what Nametag said, and Saltire diagrammed.
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  #9  
Old 03-21-2008, 06:39 AM
zut zut is offline
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What happens when you put the original, uncut ends together?

If you cut across the axis, like you think you did, the halves will attract. If you cut across the axis, like Nametag suggests, they will repel (but attract if you flip one half over).
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Old 03-21-2008, 06:49 AM
Napier Napier is offline
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I agree with Nametag, Saltire and Zut. I've cut or broken several magnets and seen that if you cut along with the field or axis, you get two smaller parallel magnets that repel, and if you cut across the field or axis, you get two smaller series magnets that attract.

There are all sorts of arrangements of poles. Some magnets have more than two poles.

The ways I know to look for poles are to use a known magnet as a probe, to make a measurement device out of a Hall effect or other similar field intensity transducer, to move wires around and see what voltages correspond with what movements, and to use iron filings or ferrofluid or other media that show field lines.
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