3.2. Microscopic theories:

        The relationship cause(dqe)-effect(dF) in the expression 3.6 -- together with the operational indetermination of dqe -- increases theorization. So let us admit that the ids current element belongs to an ohmic conductive current i and that we can vary the current but keeping the ds element constant. The immediate consequences are given by 3.2: dF is proportional to i. If dF varies with i, then vd and/or dqe -- according to equation 3.6 -- should also vary. There are three theoretical possibilities:

a) dqe is constant and dF depends exclusively on vd;
b) vd is constant and dF depends exclusively on dqe;
c) dqe and vd vary with i.

        We will discuss just the first possibility since it represents the basis of Drude’s (1900) and Lorentz’s (1909) theory concerning electric conduction, based on the free electrons model, or incompressible electric fluids model [18].

        According to the incompressible electric fluids model in a conductor there exists a gas of electrons that does not by itself affect the intensity of the electromagnetic field for the negative charges are compensated by the positive ones. The mobile charges would be should be dragged by the electric field, and the speed of this movement (vd) would be the only one to play some part in the genesis of the magnetic field. The dqe factor in the expression 3.6. affect the modulation of dF exclusively in terms of the characterization of the structure of the conductive material. According to Tipler [19]:

This model successfully foretells Ohm’s law and it relates conductivity and resistance to the movement of the free electrons in a conductor. This classic theory is useful to the understanding of conduction, although it has been substituted for a more modern theory based on Quantum Mechanics.

        In other words, the theory failed because it needed some ad hoc corrections that could make it compatible with the experimental discoveries; and whatever interpretation Quantum Mechanics might offer to the physical phenomenon, the truth is that the (a) possibility has not been experimentally confirmed.

        So we leave this topic with a certainty which is backed by experiments: the magnetic field of a current element depends on the dqe electrolytic charge contained in this element and consequently on the number of electrons that determine it. This fact -- together with the cylindrical symmetry of the field -- takes us to the following corollary:

C-6: Corollary 6

In an electric current electrons flow with their polar axes which on the average coincide with the current direction.         a