# Magnetic field

1. Feb 7, 2012

There are two hemispheric magnets, both of them have S on the outer surface and N on the inner surface. If I put them together to form a hollow ball, assuming they are so close that no empty space in the interface, what happens to the magnetic field (inside and outside)?

Since magnetic field lines must start from N and end at S, what I think is that the field line will not "come out" from the inner surface any more as it cannot connect to the outer surface of the magnet. So this ball is not longer a magnet, is it right?

2. Feb 7, 2012

### clem

That arrangement will have a complicated magnetic field. While no net field leaves the ball, there will be field lines leaving at some points and entering at others.

3. Feb 7, 2012

### Skaperen

There will also be "magnetic pressure" trying to push the hollow ball apart (as would be felt while trying to push the two halves together). So it will still be a magnet. I'd love to be able to try this.

4. Feb 7, 2012