# Does eletron spin cause magnetic field?

1. Apr 13, 2013

### brianhurren

I read somewhere that a magnetic field is caused by the spin of a charge particle, in most cases the electron. So, I take it then that the electrons in the eddy currents in a bar magnet are all spinning in the same direction?
Also, do those eddy currents induce currents in the virtual electrons in the space surrounding the bar magnet, thus extending the field beyond the bar magnet?

if one field encounterd another field with particles of same energy level and spin, would Pauli exclusion principle cause them to repeal?

2. Apr 13, 2013

### Staff: Mentor

Which eddy currents do you mean?
The (or most) electron spins in a bar magnet are aligned.
Virtual electrons are not real. That approach will not lead to anything but confusion.
The field does not need electrons to be there - the field of the bar magnet just extends beyond the bar magnet according to Maxwell's laws.
I don't think this question makes sense.

3. Dec 3, 2014

### oflittleuse

I am questioning the use of a theory or law to physically define something. Sure, Maxwell mathematically defined electrical phenomenon, but what is a magnetic field? It is a force, associated with magnets and electric current, but what physical properties/matter is it made of.? Please use permanent magnet soz I can understand...:)

4. Dec 3, 2014

### Khashishi

The electrons do have a magnetic field which has to do with their "spin". This has nothing to do with eddy currents, which refer to induced currents by a changing magnetic field. Sometimes the magnetic field outside the magnet is said to be composed of virtual photons, not virtual electrons. But this is just one way of modeling it, and you shouldn't think of this picture as gospel.
You are confusing fields with particles. Pauli exclusion principle will prevent two identical fermions (of which electrons qualify) of the same energy and spin from occupying the same space. Fields are algebraic structures which don't 'encounter' one another. There's just one electromagnetic field, everywhere; and there is a value of the field at any point in space-time. There's also an electron field in quantum field theory. It doesn't make sense to talk about fields repelling each other in the way you would talk about particles. The particles, on the other hand, do repel each other in a way. See electron degeneracy pressure.

5. Dec 3, 2014

### Staff: Mentor

This is a question for philosophy, not for physics. In physics, "magnetic field" is a way to describe experiments related to things called "magnets", "electric current" and so on. And apparently that description (via the Maxwell equations) works very well.