sci.physics.electromag

On Aug 21, 1:36 pm, Benj wrote:
> Szczepan Bia=B3ek wrote:
>
> > The above are commonly known. The hydraulic analogy is good enough for
> > steady currents. But for oscillating no. To adopt the hydraulic equatio=
ns
> > for oscillating currents the displacement current was added. At that ti=
me
> > "gas equations" did not exist.
>
> Note that no less an authority than Maxwell points out (Treatise on
> Electricity and Magnetism Chapter IV) That these analogies ESPECIALLY
> the hydraulic one is actually NOT correct or "good enough". His
> reasoning was that in the hydraulic case (and to a lesser degree in
> the "gas" case) the failure has to do with the fact that the observed
> actions in hydraulics are INDEPENDENT of the shape of the hose. In an
> electric wire, induction for example, is VERY dependent upon the wire
> shape or even if a piece of iron is nearby. Maxwell therefore
> correctly concludes that a model for electric current in a wire is NOT
> the hydraulic one and must be some kind of FIELD model with energy and
> effects arising in the space OUTSIDE the wires!
>
> Benj

You (& Maxwell) are demonstrating a classic error in logic: if A & B
form a complete set then B =3D !A but if the set consists of A, B, C
(=2E..) then B <> !A. Thus because the interactions between charged
particles are velocity sensitive (a vector) then the shape of the
motion constraining envelope (the wire) will have an effect on their
total interactions; so yes, the hydraulic model is wrong but no, the
field model is not the only alternative theory.