Re: Conserving Q/Faraday

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

William Beaty wrote:

> Another thought: an electret would create a huge external field, since
> the trapped flux extends out of the surface of the material.  A
> capacitor would be different, since the field lines end upon the surface
> charges, and the flux would only be inside the dielectric.  A "charge
> injected" plastic slab would not be an electret, it would be a plate-less
> capacitor. ... Does my reasoning on this seem sensible?

I think that positive and negative space charges deposited evenly over
two surfaces of a dielectric slab (for example, by bombarding it with
electrons and protons) would create nearly the same external field as
a capacitor, not a huge field outside. Yes, it will be a plate-less
capacitor where fields due to + and - charges interfere constructively
between the layers and destructively outside.

I suppose that the "huge field" description would be appropriate for a
single layer of a net charge. In that case the field outside the
dielectric would be larger than inside, according to the epsilon_rel.
An effective dust collector for clean rooms in labs and hospitals?
What else could such electrified slabs be useful for?
Ludwik Kowalski