Hi.

If all magnets and electromagnets form/have N and S poles, and field 'lines' go from one to the other. As I was told.

An electromagnet rod core has the pole areas as :

A ferrite or iron toroid, windings on it :

Where are the magnetic poles located ? 🤨 Yes, direct current applied.

In the case of the toroid, the field is circular, so there is a symmetry that’s not there for the bar magnet. There’s also no transition from outside to inside the material, where the field is more concentrated. Labeling anything N or S would be arbitrary, like the starting point of a circle

Thanks. Can it be said there is no poles in these ?

-Images borrowed from the web-

In classical electrodynamics there are no magnetic monopoles. Mathematically, the divergence of the magnetic field is zero. This means that at all locations, there is no source of the magnetic field (unlike the case of the electric field for which the source at a given location is the charge density at that location). Equivalently, this also means that for every hypothetical closed surface, the net flux of the magnetic field through the surface is zero (unlike the case of the electric field for which the net flux through the surface is the total charge enclosed by the surface). A magnetic pole exists where there is a surface through which the net flux of the magnetic field is in one particular direction. But because there are no magnetic monopoles, there is always a balance of north and south magnetic poles on any closed surface.

Edited May 16May 16 by KJW

Two points.

1) Whilst it is true there are no poles as such, the magnetic field lines still point in the appropriate directions as shown by the arrows.

2) You have a ferrite core. The core material is important as it gathers in or concentrates the field into itself. ferrite is about the most efficient at this.
Note also that Direct Current will not produce much field in a ferrite as the ferrites are meant for high frequency operation.
This means that they are very good at creating a fast magnetic pulse from a step current at switch on/off, which accounts for their use in very old fashioned computer memories.

Thanks, studiot. Forget the ferrite. being plain iron; the field lines are also there.

9 hours ago, Externet said:

A ferrite or iron toroid

3 hours ago, studiot said:

...Whilst it is true there are no poles as such...

Yeeeeeah ! Did I 'invent' the zeropole concept ? Should it be more valuable than a monopole ? 🙄 An iron magnet with no poles. Wow ! What would it be good for ?

8 hours ago, Externet said:

Thanks. Can it be said there is no poles in these ?

-Images borrowed from the web-

This one is a dipole. Similar to a disk magnet

https://cod.pressbooks.pub/physics1100/chapter/magnetism/