Are the poles of a broken magnet always the same?

In summary, the magnet broke into two pieces because the poles were different. Each piece had a north pole at the top and a south pole at the bottom.
  • #1
CompuChip
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Hi,

Recently I came across an annular permanent magnet (round magnet with a hole in it) which had fallen and broken in half, effectively forming two horse-shoe magnets. I noticed that the two halves had similar poles:
Code:
|---------- S     S--------
|                         |
|                         |
|                         |
|                         |
|                         |
|---- N         N---------|    

(top view)

Therefore it was impossible to put it back together because the two halves repulsed each other one way, and the way the attracted they didn't fit together anymore because it was - of course - not a perfect cut.

I was wondering whether this is a coincidence. Since these magnets are apparently quite expensive it was a bit unpractical to repeat the experiment, but something tells me that one would get this situation every time although I was unable to explain this theoretically.

Any ideas?
 
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  • #2
Are you sure you did not turn one magnet around? That looks line an unusual field configuration for your description of the magnet.
 
  • #3
Yes, it broke into two uneven pieces. Each of them was about half of the size of the original but the pieces clearly only fitted together in one way.
 
  • #4
What was the field direction (that is, where were the poles) of the ring-shaped magnet before it broke?
 
  • #5
Based on symmetry (and a little intuition) I expect that the field looked like this
antigravitywg145.gif

with a north pole at the top and the south pole at the bottom or vice versa - I don't think which option is relevant.

FWIW, I think it was a neodymium magnet like this one
neodymium-iron-boron-ring-magnet-ndfeb-16882-2518093.jpg


I also tried imagining the magnet is first cut once, giving rise to something like this:
pole.gif

but if you then cut it at the top as well I would expect two halves that attract (ie in the left half a south pole is created at the top) - apparently in the case that I observed the poles of one part got flipped.

I'm also not sure whether such a reasoning would work for a violent event like dropping it from a table.
 
Last edited:
  • #6
It is likely it retained the same polarity after you broke it also viz North pole at the top and South pole at the bottom. So if you bring the broken ends together they would repel (the north at top repelling the north at top of the other one and south at bottom repelling the south at bottom of the other one) but if you flipped one of them over they would attract (north at top of one attracts south at top of other and south at bottom of one attracts north at bottom of the other).
 
  • #7
Hmm, that is an interesting possibility which I didn't consider, physwizard. I would have thought that after breaking the ring in half you would effectively get two horse-shoe magnets.

I guess I could easily find out myself with a piece of paper and some iron filing... maybe I should have done that in the first place :)
 

What are poles of a broken magnet?

The poles of a magnet refer to the two ends of the magnet where its magnetic field is strongest. These poles are known as the north pole and the south pole.

Can a magnet have only one pole if it is broken?

No, a magnet cannot have only one pole if it is broken. Even if a magnet is broken into multiple pieces, each piece will still have two poles, a north pole and a south pole.

What happens to the poles of a magnet when it is broken?

When a magnet is broken, the two pieces will still have the same poles as the original magnet. For example, if the original magnet had a north pole on one end and a south pole on the other end, the two pieces will also have a north pole and a south pole respectively.

Can the poles of a magnet be reversed?

Yes, the poles of a magnet can be reversed by exposing it to a strong magnetic field or by heating it above its Curie temperature. This process is known as magnetization and it can change the orientation of the magnet's domains, resulting in a reversal of the poles.

What happens to the magnetic field of a broken magnet?

The magnetic field of a broken magnet will still exist, but it will be weaker than the original magnet. This is because the magnetic field is strongest at the poles, and when the magnet is broken, the poles are now located on the broken edges, resulting in a weaker magnetic field.

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