Re: why does a magnet repel after it breakes? ===|===

Whether the broken magnet attracts or repels each other depends on what its
poles look like.

If the original magnet looks like
  +-----------------------------+
N |                             | S
  +-----------------------------+
After it's broken, it becomes
  +-----------+   +---------------+
N |           |S N|               | S
  +-----------+   +---------------+
So the two parts will attract each other.

However, if the original magnet looks like
                N
  +--------------------------------+
  |                                |
  +--------------------------------+
                S

After it's broken, it becomes


         N                    N
  +---------------+   +-----------------+
  |               |   |                 |
  +---------------+   +-----------------+
         S                    S

Therefore the two parts will repel each other.

Of course, these two cases are only two simple cases. In reality, the poles
of a magnet can be more complicated. This just illustrates how the poles
affect behavior of magnets.