Re: Capacitor charge, were is it?

To: tesla-at-pupman-dot-com
Subject: Re: Capacitor charge, were is it?
From: "Robert W. Stephens" <rwstephens-at-ptbo.igs-dot-net>
Date: Sat, 2 Nov 1996 00:10:54 -0500
>Date:          Thu, 31 Oct 1996 22:25:16 -0700
>From:          Tesla List <tesla-at-poodle.pupman-dot-com>
>To:            Tesla-list-subscribers-at-poodle.pupman-dot-com
>Subject:       Re: Capacitor charge, were is it?
>Reply-to:      tesla-at-pupman-dot-com
>
>>> Subject: Re: Capacitor charge, were is it?
>
>>From pgantt-at-ix-dot-netcom-dot-comThu Oct 31 21:48:51 1996
>Date: Thu, 31 Oct 1996 02:11:50 -0800
>From: pgantt-at-ix-dot-netcom-dot-com
>To: tesla-at-poodle.pupman-dot-com
>Subject: Re: Capacitor charge, were is it?
>
>On 10/28/96 22:25:36 you wrote:
>>
>>> Subject: Re: Capacitor charge, were is it?
>><MASSIVE SNIP>
>>
>>Good post Bert,
>>
>>You've put into similar words what I just wrote in reply!  (I was away 
>>for the weekend.)  The charge resides in the dielectric because that is 
>>where the work was done.  In solid dielectrics it is referred to as 
>>polarization (molecular gig goin' on here).  In space, (no molecules) the 
>>purity of the charge retention by space itself is amazingly deceptive.  
>>Another point you noted is that the solid dielectric/air junction is a 
>>surface value or feature!  This is significant and bear back to the 
>>original post I made regarding interfacial points of differing dielectric 
>>constants.  To have a capacitor, at least one metal or conductive surface 
>>must be present at all times, somewhere.  The capacitors we are used to 
>>involve soild dielectrics and two separate plates.  Charge spearation can 
>>even occur between two different dielectrics.  Charges and electrostatic 
>>goings on are a dielectic related thing.  To make them do work we need 
>>the metal stuff to collect them and transport them.
>>
>>I noted one post making a little jab at what would certainly be me 
>>regarding to much theoretical concerns here.  Man this is where theory 
>>shines and fails.  It seems its all theory and real hard to grasp 
>>intuitively.  Frankly, I think a lot of thoughts on this area are just 
>>that!  There is only one true physical reality but lots of thoughts and 
>>intellectual wind gusts.  I'm not so sure science has the grip on this 
>>subject to the degree they would like.  We got equations up the wazoo 
>>which when solved yield solutions to real work problems but the little 
>>minutia and quatum goes on at the gut level are still just a crap shoot 
>>in our understanding.  No one really knows more than a broad overview. 
>>(more than sufficient for real world apps)
>>
>>Richard Hull, TCBOR
>>
>
>Just to throw in my two cents worth, I agree with Richard.  The matter of 
>dielectrics is an interesting one.  Having worked with some pretty novel 
>stuff in my professional history, I have had ample opportunity to develop 
>some interesting capacitor applications based on dielectric properties.  One 
>of these devices was a capacitance hydrophone that worked using water as a 
>dielectric.
>
>Water as a dielectric has one particularly interesting property and that is 
>that the relative dielectric constant is about 80!  This means that you can 
>obtain a relatively high value of capacitance with smaller area.  Have you 
>ever heard on anyone using a water based capacitor?  I suppose one would 
>have to use degassed, deionized water, and I might expect that the breakdown 
>voltage would be relatively high if the water had no contaminants.
>
>Any comments?
>
>Phil
>
>Phil Gantt (pgantt-at-ix-dot-netcom-dot-com)
>http://www-dot-netcom-dot-com/~pgantt/intro.html

Phil,

I've looked at this idea and concluded that I would be unable to 
obtain the necessary purity of the containment vessel and electrodes 
to prevent contamination of the ultra-high pure water required.  I also suspect 
that most commonly available metals which are necessary as the 
electrodes and plates will leach too many metal ions 
into the water through electrolysis that unless you use gold or 
platinum electrodes you will have a short lived capacitor.  This is 
one case where I sure hope that I am wrong.  This could make a  _very_ 
compact high voltage capacitor!  I don't know if the dissipation of 
water as a dielectric would be too useful at the low Tesla coil RF frequencies
though, just probably good only for big DC storage wells.  If water had low
dielectric dissipation at RF, microwave ovens would not work.

rwstephens