Re: capacitance of a disk

[Ludwik Kowalski <KowalskiL@MAIL.MONTCLAIR.EDU>]

The field is always normal at the surface of a conductor.
You only need to know the field at the surface to
calculate C. Once the sigma distribution of the disk is
determined we can calculate C=Q/V, where V is the
assumed constant V of the disk (with respect to V=0
at infinity) and Q is the sum of dQ=sigma*dS over the
entire disk surface for that value of V.
Ludwik Kowalski

Eugene Mosca wrote:
> However, it seems to me it is not correct for a uniformly
> charged disk of finite radius. The electric field of such a
> disk is not normal it's the surface, except on the axis.