Re: Confused by a derivation.

[John Mallinckrodt <ajmallinckro@CSUPOMONA.EDU>]

On Sun, 3 Feb 2002, Ludwik Kowalski wrote:

> ... two layers of sigma in a capacitor reside on metallic
> plates and each plate produces E"=sigma/eps_o.

No.  Gauss' law shows that each layer produces sigma/(2*eps_o) on
each side of the layer.  The result from the + layer looks like
this:

          ^ ^ ^ ^ ^ ^ ^ ^ ^
          | | | | | | | | |
          ++++++++++++++++++
           | | | | | | | | |
           v v v v v v v v v

When the effect of the - layer is included we find that the field
between the plates is sigma/eps_o and elsewhere it is 0.

John Mallinckrodt      mailto:ajm@csupomona.edu
Cal Poly Pomona          http://www.csupomona.edu/~ajm