Take a magnet. Punch it flat so you now have a foil with a north side and a south side. Bend into a tube, so north is outside and south is inside. Finally bend the tube into a doughnut.
Will the doughnut behave like a magnetic monopole? If not: Why not?
You start the entire process with a magnet that has no net flux of magnetic field through a closed surface that surrounds it. The net flux of magnetic field through a closed surface, much like the net flux of an electric field, is independent of the shape of a source of the field inside the surface. That is, punching the magnet flat, rolling it up, and even twisting the magnet around cannot change the net amount of magnetic field flowing through an arbitrary closed surface around the magnet, which happens to be zero for a magnetic dipole. For it to become a magnetic monopole, the amount of magnetic field through an arbitrary surface must change spontaneously from zero to some non-zero amount. Since nothing is added to what is inside the surface, then the divergence theorem would ensure that there cannot be a difference in the flux before and after we have contorted the magnet. Since a magnetic monopole has non-zero flux and a regular magnet has zero flux, thus it cannot be reshaped into a monopole.
I guess this is the same question as "If you have two bar magnets and were able to somehow fuse the two south ends together, would you then have a magnetic monopole" or something. Magnetism on a molecular level works by the particular alignment of particles. Those particles are not locked in place and can be realigned. That's why something that isn't magnetic can be magnetized, demagnetized, and remagnetized.
