Combined bar Magnets
Most recent answer: 07/27/2015
- Martin P Joseph (age 26)
Your suspicion that the combination won't have a North or South pole is correct. The symmetry tells you that, since each end is an equal combination of North and South.
You started out with two dipole magnets and combined them so that their dipoles canceled. Now what you're left with is a quadrupole. Say that each magnet was, for simplicity, a 2x1 rectangle so that the combined magnet is a square. Although either magnet by itself changed the signs of its fields when rotated 180°, for the combination rotating 180° just brings it back to an equivalent position. Rotating by 90° approximately just changes the sign of the fields. (For a pure quadrupole, that would be exact, but in this case there are octupole etc. moments too.)
There are other types of magnets that have no North or South pole. For example, a toroidal magnet has none.
(published on 07/27/2015)