I will be happy to give up if somebody can demonstrate that the picture
described below (with field lines LOCALLY perpendicular to each metallic
disk) is not compatible with an accepted law or principle. Perhaps there is
a law which prevents lines from "bending and unbending" but I do not recall
it. In the same spirit I wander if Maxwell's laws can be used to demonstrate,
somehow, that each static line must be confined to a single plane. Call such
rules "Faraday's no-bending and no-twisting principle", if you wish. This
is not a call for a demonstration; only for an honest statement that it
exists, or can be performed.
> I was originally thinking about lines, semi-quantitatively, without
> imposing any line crossings. The center line is along the axis but all
> lines originating at r=R/8, for example, bend and are captured by the
> other plate at r=R/2, ..... etc.
Sorry for being a nuisance; I know we are no longer dealing with the
original problem. Where else can such silly questions be asked by a busy
physics professor?
Ludwik Kowalski