you will always have some leakage current across a capacitor. It can be
peripheral surface current on the edges of the capacitor. Even the bulk
dielectric can have current so-called space-charge-limited current
proportional to (voltage)^2. This is a steady-state DC current but is very
low at low applied voltage. You can check out this paper for details:

A. Rose, "Space-Charge-Limited Currents in Solids," Physical Review,
vol.97, no.6, pp.1538 (1955).


Yours sincerely,

Isaac Chan

Ph.D. Candidate
Dept. Electrical & Computer Engineering
University of Waterloo
200 University Ave. W
Waterloo, Ontario, Canada
N2L 3G1
Tel: (519) 888-4567, ext. 6014
Fax: (519) 746-6321
[email protected]
http://www.ece.uwaterloo.ca/~a-sidic


On Fri, 15 Oct 2004, allwyn allwyn wrote:

> Dear members,
> I am modelling a fluidic systems by means of simulating it as an
> equivalent electrical circuit. I have a few doubts and please help me
> in solving it
>
> I am modelling a fluidic capacitance which consists of a membrane
> deflected by means of pressure diffrence. hence there is no fluid flow
> across the membrane.here I have some doubts.
>
> 1. In electrical capacitance , is there is a flow of charge through
> the capacitor.
>    because physically the capacitance has a dielectric or an insulator
> which cannot pass charges in it.
>
> 2. so when I am measuring current across the capacitor what exactly I
> am measuring ? . Is it the charge difference between the two plates.
>
> 3. where can I learn more about capacitance. because as an electrical
> engineer I always think about alternating current flowing through the
> capacitor
>
> Thank you
>
> Allwyn
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