Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: thedoc on 02/08/2013 03:30:02

Title: Does a bar magnet lose magnetism if broken?
Post by: thedoc on 02/08/2013 03:30:02
Wilson asked the Naked Scientists:
   
Would a bar magnet lose some of its magnetism if it is bent and broken into two?

What do you think?
Title: Re: Does a bar magnet lose magnetism if broken?
Post by: CliffordK on 02/08/2013 05:42:48
Breaking a large magnet in half should create two half-magnets, each with half the strength of the original. 

Is any magnitism lost?  Perhaps a little along the edge, or anything lost with the cut. 

The strength of the magnet will depend on the orientation of the parts.

The two magnets should be more or less equivalent.
N --- S
NS NS

Orienting the magnets next to each other may make the magnet slightly stronger.
NS
NS

However, the magnets won't like being oriented in the same direction, and may spontaneously reverse, which would create a weaker field.
NS
SN
Title: Re: Does a bar magnet lose magnetism if broken?
Post by: tecvia on 02/08/2013 23:28:00
I agree w/ all except some of the domains will lose alignment because of the trauma and field density will suffer.   The side by side poles is very destructive of the normal flux path in returning to continue the cycles of charged particles into flux into charged particles, into flux etc., etc.   What you cannot do w/ permanent magnets is interfere w/ both or either of these two primal forces completing its cycle.  The fields will decay significantly.   Reverses will not occur unless the smaller domains is driving to zero flux, while some restarting flux still resides in the other, although of opposite polarity, and restarts the zero in the other direction.  Tecvia