Why the poles parts of the magnet are stronger then the other parts of the magnet?

1. Sep 4, 2007

stmartin

Are the force around the poles compressed, so it makes the poles of the magnet stronger than the other parts? Thanks.

2. Sep 4, 2007

genneth

There is no "force" around a magnet. There is a field. The field affects things with magnetic charge -- in the case of magnetisms, magnetic dipoles. The field looks roughly like that pattern you get when you sprinkle iron filings about the magnet. The force exerted on a dipole due to a field is proportional to the strength of the dipole (obviously -- we actually define strength of dipoles this way) and the rate at which the field falls off. Note that all dipoles will experience a torque that tries to align them to the field (which is why the field is shown by iron filings -- they're miniature dipoles), but only a non-uniform field causes a linear force, displacing the dipoles. If you study the field lines about a bar magnet, you will notice that the field lines "come together" to end at the pole -- this signals the fact that the field is strongly varying there, because you go from very few lines crossing per area to many lines crossing per area. Thus a dipole placed there feels a much greater force.

3. Sep 4, 2007

stmartin

Ok, thank you very much.