Re: Current in a wire

[Joel Rauber <Joel_Rauber@SDSTATE.EDU>]

Tom,
Is this a response to my posting regarding the appearance of excess charge
on the surface and a fundamental reason as to why it can not appear to the
interior?

If not, to quote the famous Emily Latella; "Never Mind".

If so, then

The superconducting situation is irrelevant.

 From what? do we deduce that the excess charge exclusively resides on the
surfaces of the conductor.  Remembering that we are in a situation where the
electric field is not zero to the interior of the conductor, and the normal
use of Gauss' law to show excess charges resides on  the surfaces of a
conductor in electro-static situations does not apply as that arguement
typically utilizes the fact that E=0 to the interior of a bulk conductor.

I just realized I think I have a partial answer.

Joel Rauber



> -----Original Message-----
> From: phys-l@lists.nau.edu: Forum for Physics Educators
> [mailto:PHYS-L@lists.nau.edu]On Behalf Of THOMAS SANDIN
> Sent: Thursday, March 23, 2000 11:31 AM
> To: PHYS-L@lists.nau.edu
> Subject: Re: Current in a wire
>
>
>         In a normal metal, the current is uniformly
> distributed across the
> cross section of the wire for dc and low frequency ac.
>         (In contrast, all the current is on the surface if the wire is
> superconducting (Type 1). This distribution occurs because of the
> Meissner effect--there is no magnetic flux within the bulk of such a
> superconductor.)
>         Excess charge appears on the surface at bends of a normal
> wire--required to bend the electric field along the axis of the wire.
>                                                 Tom Sandin