  Application of the generalized continuity equation reveals that the drift
current in conductors is equivalent to a negative diffusion current. A
phenomenological model of conductivity is developed using the generalized
continuity equations. Consequently, a limiting conductivity is obtained that
amounts to $1.09\times \,10^9\,\Omega^{-1}m^{-1}$. A magnetomotive force
(current) is hypothesized to exist, which is exhibited when a voltage changes
with time. Magnetic charges and currents are found to be related to
displacement current.
