Maxwell's theory needs the field concept. The theory says and electric force can not be present without an electric field.
If we follow Maxwell's theory to the letter, it says there will be no electric field outside a current carrying wire. Consequently, the theory leads one to expect an electric force is absent as well. Weber's theory is not built on the field concept, so this curious expectation does not arise. My analysis is based on reading of this preface to the book suggested by Taylor J. Smith. http://www.ifi.unicamp.br/~assis/Preface-Webers-Electrodynamics.pdf Harry ----- Original Message ----- From: "Stephen A. Lawrence" <[email protected]> Date: Monday, September 14, 2009 6:18 pm Subject: Re: [Vo]:The Electric Field Outside a Stationary Resistive Wire Carrying a Constant Current > > > Harry Veeder wrote: > > fyi Harry > > > > Foundations of Physics © Plenum Publishing Corporation 1999 > > 10.1023/A:1018874523513 > > > > The Electric Field Outside a Stationary Resistive Wire Carrying a > > Constant Current > > > > A. K. T. Assis, W. A. Rodrigues Jr. and A. J. Mania > > > > Abstract We present the opinion of some authors who believe > there is > > no force between a stationary charge and a stationary resistive wire > > carrying a constant current. > > That's stated a lot, but it's just sloppiness. Anyone who knows > electronics realizes it's not really true. > > A good conductor carrying small current has *nearly* zero voltage drop > along any small length, and calling the drop "zero" is usually "good > enough". But really the voltage drop along any segment is equal to > I*Rwhere R is the resistance of that segment. > > When the voltage drop along a (resistive) wire is nonzero, then *any* > path which leads from a higher voltage point on the wire to a lower > voltage point on the same wire must traverse the same exact potential > change, which means that there must be an electric field *outside* the > wire, running parallel to the wire. > > This is well known but, as I said, usually neglected, because it's > usually too small to matter in real-world problems. > > The fact that there's an "image charge" induced in the wire as well, > which consequently must be having its effect on the charge sitting > outside the wire, is certainly the case and could even be called > "obvious", but it's not something I ever thought of until I saw it > mentioned in the abstract. :-) > > > > We show that this force is different > > from zero and present its main components: the force due to the > > charges induced in the wire by the test charge and a force > > proportional to the current in the resistive wire. We also discuss > > briefly a component of the force proportional to the square of the > > current which should exist according to some models and another > > component due to the acceleration of the conduction electrons in a > > curved wire carrying a dc current (centripetal acceleration). > > Finally, we analyze experiments showing the existence of the > electric> field proportional to the current in resistive wires. > > > > complete paper available here: > > http://www.springerlink.com/content/q6634pp556m08500/fulltext.html > > > > > >
