Re: Electrostatic Questions

Tesla List wrote:
> >From rwall-at-ix-dot-netcom-dot-comSat Aug 24 22:08:35 1996
> Date: Sat, 24 Aug 1996 07:01:30 -0700
> From: Richard Wayne Wall <rwall-at-ix-dot-netcom-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Electrostatic Questions
> 8/24/96
> I have a couple of questions regarding electrostatics.
> In the metal pail capacitor experiment where the cap is charged and the
> pails are removed and grounded and then later replaced, it is obvious
> that the charge resides on the dielectric rather than the metal plates.
> Question 1: If a gas (air) or liquid dielectric cap is charged and the
> liquid is drained or the air is blown away from the plates what happens
> to the charge on the cap?

In air and a vacuum, it goes bye-bye!  Charge is distributed over larger 
area. (it is never lost-conservation laws-)  But, for us real people who 
put on the real charge, with real energy, it is REALLY- just gone!!!  
Liquids can be charged and transported, though.  There are many mysteries 
involving the study of non-standard, non-bulk, dielectrics which are 
subtle.  The answers to these questions are, often, just not known by 
many physicists if questioned in a situation where they can't research 
the matter! I have caught several off guard.  There is just no money in 
trivia knowledge of old dead subjects like electrostatics and some 
physicists just dodge or avoid definitive answers (Good thing too as 
there are few definitive answers available for some phenoena!)
This may sound bad for them, but these tenured icons of science are just 
like you and me only vastly more practised is narrow areas.
> R.Hull

> I am very interested in DC properties of TCs.  I have devised various
> schemes to add DC bias to the coil so that the TC discharge will also
> exhibit a DC bias  - sort of pulsating DC from the toroid.
> Incredibible DC voltage and current may be developed with only a small
> to moderate TC.
> One way to introduce this DC bias is with a main capacitor that
> selectively charges during the AC waveform, ie., charges easier
> positively or negatively or vise versa.  Note this is not an
> electrolytic or any other polarized cap.  Since most caps are
> essentially two metalic plates on either side of a dielectric,
> selective charging would ordinarily be unusual.
> Question 2:  Has anyone made a cap by placing the metal plates on an
> electret dielectric?  Seems to reason that an "electret cap" would
> selectively charge/discharge.  The big question is can ordinary
> polymers such as polyethelene be made (converted) into an electret?
> Richard H. or Kim G?

I have only limited experience with electrets.  They seem magical, but 
are really just special dielectrics with properties which let them 
continually facilitate charging.  This is key to remember.  The charging 
of plates from electrets still require some triboelectric action (input 
energy) and charge separation through motion!  (separating the plate to 
be charged from the electret.)  Electrets can be discharged forever 
without proper electrostatic shielding.  Weak electrets require frequent 
recharging.  The classic electret of bygone ages is a mix of Beeswax and 
Carnauba wax.  Modern electrets include some forms of specially prepared 
teflon.  Oleg Jefimenko and R.A. Ford have books which discuss electrets.
Richard Hull, TCBOR