Re: [Phys-l] defn of capacitance

["Bob Sciamanda" <trebor@winbeam.com>]

The texts require at the outset that the charged objects are conductors.
----- Original Message ----- 
From: "John Denker" <jsd@av8n.com>
To: "Forum for Physics Educators" <phys-l@carnot.physics.buffalo.edu>
Sent: Monday, February 11, 2008 4:07 PM
Subject: Re: [Phys-l] defn of capacitance


> On 02/11/2008 01:38 PM, Bob Sciamanda wrote:
> > Textbook treatments of this subject include a proof that the Cij's are a
> > function only of geometry.  This is an important part of the usefulness 
> > of
> > this model.  Your treatment does not seem to include this point.
>
> Proof???  I think it's an assumption requiring an
> approximation ... not a proof.
>
> It's bad luck to prove things that aren't true.
>
> For example, the assumption does not hold if
> varactors or other lightly-doped semiconductors
> are involved.
>
> Thanks for pointing out this gap in the logic;  I
> just now added a paragraph documenting the required
> assumption.
> _______________________________________________
> Forum for Physics Educators
> Phys-l@carnot.physics.buffalo.edu
> https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l