A note on the quasi-static approach in teaching electromagnetics

It is argued that in teaching electromagnetics, the classical electrostatic introduction can be bypassed if one admits the existence of time harmonic fields at the outset where the frequency is sufficiently low that propagation effects can be neglected. Thus, one still deals with Laplace's equation and, for convenience, can characterize the medium in terms of its admittivity. Electrostatics are then recovered later as a special case by letting the conductivity vanish. Then on applying Ohm's law, it is simple to deduce in expression for the radial electric field E/sub r/. It is now possible to treat concrete physical problems such as deducing the quasi-static electric fields of a linear-current-carrying wire for any conductivity and permittivity in the ambient medium. By using image theory the student is also introduced to simple boundary-value problems where the effect of a ground plane, for example, can be handled.<
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