On 11 mai, 12:36, PCB wrote:
On May 11, 6:02 pm, Tom Roberts wrote:



PCB wrote:
I read somewhere that only electric currents generate magnetic fields.

That is incorrect. The intrinsic spins of elementary particles also
produce magnetic fields.

Where is the electric current in a permanent magnet?

There is none.

Is a permanent magnet a frozen electric current in matter?

No.

It seems that the electric current in a magnet would like to flow, but
it cant.

No. Iron is conductive, as are most other permanent magnets.

The bulk magnetization of a permanent magnet is due to the alignment of
spins in the constituent atoms. This cannot be understood classically,
QM is required.

Tom Roberts

But sir, QM is false, never makes accurate predictions.

QM only probably will make a prediction, but probably not. I learned
that if a theory does not always make a predicted prediction, always,
than that theory is false, or at best useless.

So the question still remains untouched, and I have a permanent magnet
which is not a conductor at all.

No electrical conduction is required. Ceramic magnets for example
are not conductive.

You will find all the particular of what interests you here in the
CRC handbook of Chemistry & Physics, p 12-117

What alignment of spins? You mean synchronization of electron spins?

In all atoms, each orbital becomes complete when two electrons
associate by inverse parallel spin. Electrons behave like small
magnets having two magnetic poles. The magnetic pole duality
is named spin (a strange misnomer cooked up before spin was
clearly identified as being the magnetic aspect of electrons.)

To put it simply, in some atoms, some layers close to the
outermost do not get filled completely and contain isolated
electrons that are partially free to rotate locally.

When circumstance allow (typically an external strong magnetic
field will force a lot of these electrons to align contrary
to the direction of the external field. When the external
field is removed, local electromagnetic equilibrium will
tend to keep them align parellel which will cause their
fields to add up to make up the macroscopically detectable
field that we can use.

This has been understood for more than 80 years, even though
QM trained physicists tend not to learn about it since this
observed fact is in contradiction with QM.

Because the atoms are still round in a permanent magnet, you cant
align somthing which is round.

You need something to be elongated in order to align them.

Am I wrong? Where?

Atoms are not really "balls" you know. They are mostly
vacuum with the electrons captive at certain locations
in the volume detemined by the whole atom. Electrons
keep their individual characteristics, including their
spin orientation, which can only be anti-parallel for
orbital filling and for covalent bound (between atoms)

Only electrons isolated alone on their orbital can
be part of a larger magnetic field. See the CRC ref
I mentioned for the complete story.

André Michaud