Instructables

why there is change in polarity in a bar magnet when it breaks?

a bar magnet when breaks does not attracts but repels from where it has broken ...

  like [N-------S]   is a bar magnet
on breaking it should be like  [ N---S} {N---S ]
but it happens to be  [N----S} {S---N] ..  means there is "repulsion" between them
WHY SO ??

(Pratically seen)

mrmerino1 year ago
If you break a magnet like the diagram you made up there, the new poles will attract each other. mpilchfamily seems to have a good idea, maybe the break was parallel to the poles and not perpendicular.
aporak (author)  mrmerino1 year ago
perpendicular ... like you break a stick from the middle..
aporak (author) 1 year ago
still not satisfied with the answers.. :(
rickharris1 year ago
When a material can be magnetised this is because it's atomic make up allows the internal magnetic domains to be aligned. Thus rather than a random distribution they all / mostly face N - S N - S Thus one end becomes N and one end becomes S.

If you break the magnet it will divide between domains and so you will get a S - N effect to match the other ends. Although to us the break is in a random place I suspect that at the atomic level there is a lot going on before the crystals part.

graphic example

N-S N-S N-S N-S (BREAK) N-S N-S N-S N-S

Wiki ref

http://en.wikipedia.org/wiki/Magnetic_domain
Re-design1 year ago
If the magnet was put under great stress or hit really hard to break it, a magnet can loose its magnetism. So I guess it might suffer a reversal. I've never seen it happen but then I've never broken a bar magnet.
Are you certain the poles are running horizontally across the length of the magnet and not top to bottom or some other orientation?

If your magnet is polarized as you pictured then they wouldn't repeal each other like your seeing. From what you describe it sounds like the top half of the magnet is N--S and the bottom half is S--N. So half the magnet was magnetized vertically one way and the other half was magnetized vertically the other way rather then a single north and south through the horizontal plain. Such as the multi pole magnet sown in the below link.

http://www.magnaworkstechnology.com/magnet_orientation.shtml