Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: DoctorBeaver on 23/07/2008 18:53:34
-
If you take 2 identical bar magnets and place 1 on top of the other with the north pole of 1 adjacent to the south pole of the other, what happens to the magnetic field?
-
If you take 2 identical bar magnets and place 1 on top of the other with the north pole of 1 adjacent to the south pole of the other, what happens to the magnetic field?
You want to make it disappear, isnt'it? It's not possible; to achieve that, you should make the sources coincide exactly, that is you should overlap the two (equal) magnet; but that's impossible: the space occupied by one cannot simultaneously be occupied by the other.
At a very large distance (with respect to the bar's dimensions), however, the field goes to zero very fast, that is, you're less and less able to determine that there are two magnets, instead of no ones.
-
lightarrow - no, I wasn't thinking about making it disappear. I was wondering whether something made from, say, iron would be more attracted to them as a result. The iron wouldn't care if the north or south pole were nearer. So would having the 2 magnets together increase the strength of the magnetic field or would it stay the same?
-
If an N and S pole are brought close together, in pictorial terms, the field lines tend to concentrate between the poles, making the local field much stronger but the external field less. That is why, I think, all old magnets were made in a horseshoe shape so that you at least got one area of relatively strong field from a relatively weak magnet.
Think of field lies as unbroken loops. They go into a magnet* and come out 'the other end' then launch off into the surrounding space, only to return. A field line may go through a number of media (other permanent magnets or bits of iron - temporary magnets). The 'concentration' of lines corresponds to the field strength and is increased in or near regions of high permeability.
*Or the coils of an electromagnet.