Rigorous definition of magnetic poles?

  • #1
443
28
Hi.

Since there haven't been observed magnetic monopoles so far, what exactly do we mean when we talk about the north/south pole of a magnet? Is it something like "north is where the field lines exit a solid body" and "south is where they enter" or is there a more rigorous definition?
 

Answers and Replies

  • #2
35,806
12,532
You can find the main axis (given by the dipole moment), but assigning points like "exactly here is the pole" doesn't make sense. Typically one half of the magnet is called south pole and the other half is called north pole, but that doesn't work for more complex magnet shapes where the definitions get a bit arbitrary.
 
  • #3
Vanadium 50
Staff Emeritus
Science Advisor
Education Advisor
2021 Award
27,691
11,972
There is a rigorous definition, but not at the B level. It involves vector calculus, and the idea is that if you have a volume where you have more flux lines going in than out it contains a pole. Magnetic fields do not do this, so the best you can do is point to some non-enclosed region and say "this region is pole-like".
 

Related Threads on Rigorous definition of magnetic poles?

  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
9
Views
14K
  • Last Post
2
Replies
31
Views
6K
  • Last Post
Replies
3
Views
1K
Replies
10
Views
26K
  • Last Post
Replies
6
Views
5K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
4
Views
9K
  • Last Post
Replies
6
Views
12K
Top