I remember reading in a book that the theory of electrons moving in a current carrying conductor is only partially correct.
According to the book, and if I recall correctly, the conductor acts as a waveguide that channels the electromagnetic field and the movement of electrons is just a secondary effect of that.
I’ve searched the internet but couldn’t find that theory and I don’t remember the name of the book.
Read the section on Drift Speed in Wikipedia - Electric Current
I think it explains it very well. I quote " Typically, electric charges in solids flow slowly. For example, in a copper wire of cross-section 0.5 mm2, carrying a current of 5 A, the drift velocity of the electrons is on the order of a millimetre per second. To take a different example, in the near-vacuum inside a cathode ray tube, the electrons travel in near-straight lines at about a tenth of the speed of light.
Any accelerating electric charge, and therefore any changing electric current, gives rise to an electromagnetic wave that propagates at very high speed outside the surface of the conductor. This speed is usually a significant fraction of the speed of light, as can be deduced from Maxwell’s Equations, and is therefore many times faster than the drift velocity of the electrons. For example, in AC power lines, the waves of electromagnetic energy propagate through the space between the wires, moving from a source to a distant load, even though the electrons in the wires only move back and forth over a tiny distance."
There is arguably a chicken and egg question here.
If you get a solid and put an electrical potential across it, if the electrons are able to move, they will, and you get an electromagnetic field produced. If the electrons can’t easily move, you don’t and such materials are called insulators.
If you accelerate a stream of charged particles, such as the sun ejecting a mass of protons and spray them through space, you get an electromagnetic field, so pure moving charge is clearly directly creating a field too.
However, in a vacuum, the electromagnetic field moves at C, not at the speed of the moving charge. Even when not in a vacuum, it is still a large fraction of C.