Re: I need help.

[kowalskil <kowalskil@MAIL.MONTCLAIR.EDU>]

Joseph Bellina wrote:

> Since the flow lines all lie in the plane of the paper, it seems to me
> that the situation is a 2 dimensional one.
> Let me describe an experiment I did some time ago which supports this
> claim.
> Construct a ring of conducting paint, and put a dot of conducting paint
> in the center.  Measure the potential as a function of distance from the
> center, plot the curve, differentiate it by drawing some tangent lines,
> and then plot the slopes as a function of distance on log-log paper.  Of
> course now you would do it with a computer.  The slope of the resulting
> line is -1, so the electric field falls off as 1/r, which is the
> characteristic of an infinite rod.   In this sense the paper can be
> seen as a perpendicular cut in the space around a charged rod.

And, consequently, you would expect the theoretical curve (b) to
match the experimental line. But this did not happen. Why?
Ludwik Kowalski