Magnetic Force field

[MikeCasssidy]

So you stick paper over a magnet and then pour iron filings on the paper and force field lines appear.
So are these force field lines real or an aberration of where the first iron filings touched; would they appear in exactly the same places? and is the magnetic field weaker between the lines or the same strength??

[ShinAce]

So you stick paper over a magnet and then pour iron filings on the paper and force field lines appear.
So are these force field lines real or an aberration of where the first iron filings touched; would they appear in exactly the same places? and is the magnetic field weaker between the lines or the same strength??

That's just a clumping effect. The 'lines' would not appear in the same place everytime, but they would have the same overall 'lobing' shape. The magnetic field is the same strength between the 'lines' as it is on the lines. Of course, if we didn't have this clumping, it wouldn't be as dramatic. It would be quite boring.

Luckily, there is a case where true lines form. This happens to superconductors(type 2). Superconductors have this interesting property that magnetic fields cannot penetrate them. The magnetic field must bend around the superconductor. That would be true for type 1 superconductors. Type 2 superconductors allow 'filaments' of magnetic fields to pass through, but they are confined to the filaments, or tubes.