the E-field (force per point-coulomb of charged mass) in the vacuum, when there are no point-coulombs of charged mass there!
Mass Is an Internal Component of Force
It is easy to show that mass is always a component of force: We will simply define force precisely. We first insist that no equation can be used as a definition; an equation simply states that the magnitude of one of its sides and the magnitude of the other side are equal. (The length of a board and the length of a human may be equal, but writing that as an equation has absolutely nothing to do with the definition of either a board or a human). So we will insist that any true definition must be an identity.
We define force F as Fd/dt(mv), whereupon mass is a component of force a priori. It follows that, if we define the E-field E as the force per coulomb, we are defining it as the force existing at a point and having a point-coulomb of charged mass as one of its major components. We may accurately now define E as E-[(Ø)(q)]/|q|, where the absolute value symbol in the denominator is essential, q/|q| being one point-coulomb. [We leave as an exercise for the reader the further reduction of this definition by treating q as (Øm)].
At any rate, with the new and correct definition of the E-field, one can see that the flow of displacement current (dØ/dt) upon a collector such as a rigid capacitor, containing a fixed charge (Øm), will result in the formation of an excess Ø upon those restrained charges in the capacitor plate, so that there is created an E-[( Ø)(q)]/|q|. Since the conventional theory considers the antigradient of the potential as an E-field, then one can now see the exact mechanism that creates this E-field that grows upon the capacitor (across its plates) as it charges. In fact, the q/|q| cannot change in a capacitor if its plates and dielectric are immovable. Instead, in that case, the Ø portion of the trapped (q) changes, producing the ( Ø) change. Since the ( Ø) component is coupled to the mass component of the fixed q as (Ø+ Ø)m, then an E-field is created and exists as E-[( Ø)(q)]/|q|.
An Ideal Capacitor Is an Electron Current Blocker
We point out that, if the capacitor's components are ideal, completely rigid, and do not physically move, then the capacitor is a "dm/dt blocker." If the charges really were frozen in place, then the potential would flow across the plates at the speed of light, via the flow of excess massless displacement current dØ/dt. In that case, an ammeter would not show the classical "exponential fall-off" of the current with time; the electron current dq/dt would occur as a single-point Dirac delta function at t=0, and would be zero thereafter. And no electrons would be able to move in zero time. The voltage would show an instantaneous adjustment to the charged value with a single step-function, and the capacitor would charge up fully, instantly, with no work (energy loss) whatsoever being done. And this charge-up of the capacitor would not dissipate in the slightest the source furnishing the voltage; there would be no electron current dq/dt through the back EMF of the source, hence no work inside it to deplete its separation of charges.
Problems With Ordinary Capacitors
However, most ordinary capacitors are much more than just an ideal capacitor. The plates move, the dielectric moves, etc. due to the forces created upon them by the E-fields created upon the trapped charges in them. The spatial translation of the resulting force moving the plates constitutes work; i.e., it dissipates some of the flowing dØ/dt energy. Each movement of the plates and/or dielectric carries with it all its internally trapped charges. The movement of those charges constitutes a substantial longitudinal electron current dq/dt, when compared to the longitudinal "drift" electron current in normal circuits. [Electrons spend most of their time moving radially in a wire, not down it.] This "moving plate and its transported charges" make an electron current, which pumps the inert electrons in the ground return line back through the back EMF of the source,