> Measuring relative surface potentials between two > electrodes simply doesn't tell you if there are excess surface > electrons on one or both or neither. It still seems pretty obvious > to me.
You can say that three times it won't make it true, whatever Lewis Carroll says ;-) Come on, what you describe is a capacitor, there are excess electrons on the surface of the most negative electrode facing the most positive one, of a very predictable total charge given by: C*Delta_V = C*(potential of most positive electrode - potential of most negative electrode) Elementary EE stuff. Only potential differences matter I tell you! Michel ----- Original Message ----- From: "Horace Heffner" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Monday, August 13, 2007 6:06 AM Subject: Re: [Vo]:Re: Only potential differences matter > > On Aug 12, 2007, at 5:03 PM, Michel Jullian wrote: > >> >> ----- Original Message ----- >> From: "Horace Heffner" <[EMAIL PROTECTED]> >> To: <[email protected]> >> Sent: Sunday, August 12, 2007 9:03 PM >> Subject: Re: [Vo]:Re: Only potential differences matter >> >> >>> >>> On Aug 12, 2007, at 6:49 AM, Michel Jullian wrote: >>> >>>> >>>> ----- Original Message ----- >>>> From: "Horace Heffner" <[EMAIL PROTECTED]> >>>> To: <[email protected]> >>>> Sent: Sunday, August 12, 2007 7:55 AM >>>> Subject: Re: [Vo]:Re: Only potential differences matter (was Re: >>>> Deflation Fusion) >>>> >>>> >>>> ... >>>>>> Your argument below is flawed because >>>>>> >>>>>> E = grad (V) >>>>>> >>>>>> is the definition of V as much as it is the definition of E, so p1 >>>>>> and p2 cannot be fixed, as you imagined, independently of the real >>>>>> charges which determine the field: once you (the power supply) >>>>>> will >>>>>> have removed all N electrons from B1 and transferred them to B2, >>>>>> then the voltage difference will be as determined by the field >>>>>> created by the real charges. What would be idealized would be to >>>>>> imagine that a power supply can impose a given voltage difference >>>>>> across two bodies, regardless of the electrons those bodies can >>>>>> shed. >>>>> >>>>> >>>>> Guess what Michel, you are certainly right about the above. >>>> <snip> >>>> >>>> The above refers to voltage differences, so you now agree that only >>>> potential differences matter? >>> >>> Absolutely not. I'll repeat the part you deleted above: >>> >>> This brings us back to the main side issue, about which I still feel >>> the same. >>> >>> The veracity your subject statement under some conditions, or lack >>> of same, is irrelevant. It is well known that classical >>> electromagnetism is a gauge theory. However, it is unreasonable and >>> irrelevant to repeatedly note that fact when a gauge has been >>> specified. >> >> I never suggested changing the gauge. > > > I never said you did. *I* set the gauge. What I am complaining > about is your arguing outside that context. You in effect keep > arguing that EM is gauge free after I have set the gauge within the > context of the problem. > > >> >>> Within the context of the deflation fusion topic, the >>> context in which you criticized changes to Figure 1, when gauge is >>> specified as I did, then *absolute* surface potential is an indicator >>> of electron fugacity. >>> I say once again that to suggest this effect >>> can be created by relative potentials and not absolute potentials >>> where potential is defined within the constraints I very clearly laid >>> out, is to miss the point entirely. It leads to nonsensical designs >>> and to the inability to understand why CF conditions may be so >>> difficult to achieve reliably. >> >> This is exactly what I dispute and call nonsensical myself. Only >> *relative* potentials of the cathode wrt the two anodes will >> determine the total excess negative charge on the cathode, and >> therefore the average excess electron density. >> Since total cathode charge is an important parameter for your >> scheme you will probably measure it in both versions, hopefully >> finding the same value will achieve what I failed to do: convince you. >> >> The fact of the subject line is well known to even first year EE >> students BTW, I don't know how versed you are in EE but have you >> ever seen a dependence on absolute voltage in the current or charge >> vs voltage laws of resistors, inductors or capacitors? > > > We've been over that many times. Once again you chose to argue out of > context. Everybody knows EM is gauge free. Once you set a gauge for > potential, however, it is not. I set that gauge a long time ago. If > you want to discuss this further please try to do it within the > context of the problem and not continue to state the obvious but > irrelevant. > > When measuring experimental values we are (at least I am) pretty much > stuck with measuring volts and amps. Surface potentials at points on > electrodes measured within a grounded Faraday cage, with the inside > of that cage acting as zero potential, should provide good > correlations with excess electrons at those points. That sets the > gauge. Excess electrons is an absolute measure, and it can now, for > experimental purposes, using that definition, be correlated with an > absolute potential. One way to set an electrostatic potential gauge > is to zero at infinity, because the universe is likely made up of > equal or very nearly equal numbers of positive and negative charges. > For brevity call this the universal gauge. Given that, the earth > should not be far enough off that zero potential to make a > significant difference in charge balance on the inside of a Faraday > cage. Charge distribution inside a grounded faraday cage where all > conductors are grounded to the Faraday cage, and no dielectrics are > included, should have very close to a 50-50 positive and negative > charge balance everywhere. If true, we then know that, inside the > cage, negative surfaces have excess electrons, positive ones do not. > We can apply our instruments to the problem in a meaningful way. > This is important. Measuring relative surface potentials between two > electrodes simply doesn't tell you if there are excess surface > electrons on one or both or neither. It still seems pretty obvious > to me. The technique is not only convenient, it is necessary to the > problem. Maybe I'm missing something. > > It could be I am missing the effect of a field applied from outside > the Faraday cage, like the typical 100 V/m atmospheric field. My > understanding of this is that the surface charges of the faraday cage > shift around to negate that field. There is no field induced > (remaining) inside the cage and no redistribution of charge on the > inside surface of the cage by that field, because it is fully negated > by surface charge movement. > > It is certainly true that if the Faraday cage were at high a enough > universal potential on the outside, with respect to the universal > zero potential that is, then this would indeed affect the charge > ratio on the inside surface of the cage. However, at any kind of > universal potential we are likely to see on the earth's surface, > including millions of volts, there probably won't be a significant > change in charge ratio inside the Faraday cage. As I noted earlier, > removing just the top layer of electrons would produce a surface > potential change of 2x10^11 volts. Using a grounded Faraday cage for > reference sounds to me like not only a good idea, but an essential > idea, to have even a clue as to what the absolute surface charge > balance is on anything within the cage. > > >> >> In any case I wish you good luck with your interesting designs. > > Thanks. This discussion has actually helped me, believe it or not, > even though we haven't made much progress of late due to digression. > > Horace Heffner > http://www.mtaonline.net/~hheffner/ > > >
