# was magnets in HDs

```Original poster: "David Huffman by way of Terry Fritz <twftesla-at-qwest-dot-net>" <huffman-at-fnal.gov>

Please view in Courier fixed font.

Magnet puzzle.
If you take a bar magnet as shown in a) and cut it vertically you will get two
magnets with like poles.
In this case the two will certainly not go back to their original position. If
you cut the magnet horizontally as in c) the poles will be N-S and the two
pieces will go back to their original position. In both cases the poles have
remained the same yet the perception might be that it has.
Now take case d) which is what you get with those brittle ceramic magnets. The
field off the broken piece will have a skew since the South pole is misshaped
and the field line tend to come out of the surface at right angles. The piece
is most like example b) and will want to turn 180 degs.
It is interesting to note that the magnetized material is trying to come apart
radially along the pole axis while it is coming together longitudinally.
Take a look at the field here
<http://www.tbcnet-dot-com/~huffman/output.pdf>http://www.tbcnet-dot-com/~huffman/ou
tput.pdf   The North pole is to the right.
Dave

a)
|NNNNNNNNNN|
|          |
|          |
|          |
|          |
|          |
|          |
|          |
|          |
|SSSSSSSSSS|

b)
|NNNNN|NNNNN|
|     |     |
|     |     |
|     |     |
|     |     |
|     |     |
|     |     |
|     |     |
|     |     |
|SSSSS|SSSSS|

c)
|NNNNNNNNNN|
|          |
|          |
|          |
|SSSSSSSSSS|
----------
|NNNNNNNNNN|
|          |
|          |
|          |
|SSSSSSSSSS|

d)
|NNNN/NNNNN|
|   /      |
|  /       |
| /        |
|/         |
|          |
|          |
|          |
|          |
|SSSSSSSSSS|

```