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Re: TC Electrostatics (fwd)
Tesla List wrote:
>
> > Subject: Re: TC Electrostatics (fwd)
>
> Subscriber: harris-at-parkave-dot-net Wed Jan 1 21:51:17 1997
> Date: Mon, 21 Oct 1996 23:59:51 -0400
> From: Ed Harris <harris-at-parkave-dot-net>
> To: tesla-at-pupman-dot-com
> Subject: Re: TC Electrostatics (fwd)
>
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> > Subscriber: hullr-at-whitlock-dot-com Tue Dec 31 22:31:30 1996
> > Date: Tue, 31 Dec 1996 11:40:38 -0800
> > From: Richard Hull <hullr-at-whitlock-dot-com>
> > To: tesla-at-pupman-dot-com
> > Cc: caydsi-at-aol-dot-com
> > Subject: Re: TC Electrostatics (fwd)
> >
> snip a bunch
>
> > I have come to understand there is a vast difference between true
> > POTENTIAL (electrostatic only), static charge and forces as compared to
> > the voltage "pressure" found in a dynamic battery within a circuit. Also
>
> > the coulomb of the AMpere definition has no relation (not even the most
> > tenuous) to the coulomb of electrostatic charge!! The difference is one
> > of current flow and magnetic field generation and the two seem unrelated
> > in spite of attempts to link them. Yet, the temptation to link them
> > remains even in my mind. I can find no electric field about a current
> > carryng wire.
>
> Hi Richard,
>
> There seems to be some fundamental difference in our perspectives.
> Everything
> you have reported about your experiments seems to be ok. But our
> interpertations is completely different. Your results are perfectly
> consistent with
> my "old fashioned" understanding of electromagnetism.
>
> 1 ampere of current though a wire will generate a magnetic field outside of
> that wire, but any electric fields will only be parallel to the axis of the
> wire
> (since the chareges follow the electric field by ohms law). Now Richard is
> asking why does this 1 coulomb per second of charge NOT generate a
> perceptible electric field around and perpendiclar to the wire axis just
> as an "electrostatic" charge would. Is does not in this case because no
> NET charge is gained by the wire as in the electrostaic case. 1 coulomb per
> second goes into the wire as 1 coulomb per second leaves the wire.
> Therefore there is no NET charge on the wire.
>
> When the circuit is disconnected so that no current flows, the charges
> can build up on opposite sides of the power supply just like if you
> were charging a capacitor. An electric field will also appear (just
> as in the capacitor) between the oppositely charged wires.
>
> In both of these cases, the charges are just ordinary electrons. In one
> cae the electrons move but the number of electrons in the wire
> is exactly balanced by the number of stationary copper ions so there
> is not net external electric field - -- in the other case the chargind
> current
> of electrons is transient and simply leaves an excess of electrons as
> compared to the copper ions in the (-) conductor and a deficit of electrons
> on the (+) conductor. The final static condition has an electric field
> directed from the + to - charges.
>
> Bottom line is: A coulomb is a coulomb no matter if its moving
> or not.
>
> You are correct that there is subtle difference in types of "voltmeters".
> A "perfect" electrometer does not depend on a continuous transfer of
> charge (infinite imperdance) so it can actually measure a voltage or
> electric potential such as the built-in voltage across a diode. But
> ordinary
> DMMs for instance are really measuring what we physics types call
> "chemical-potential-difference" which requires charge transfer. This
> kind of voltmeter has finite impedance and cannot measure a diode's
> built-in potential difference. Of course, the are different degrees of
> voltmeter impedance so the line is a bit blurred as the impedances
> go toward 10^15 ohm say.
>
> -Ed Harris
Ed,
Thoughtful post, I must cogitate on it a bit. I will note a nice
experiment just performed over the Xmas holidays.
I took my gaussmeter (FW BEll 700) and my Keithley electrometer and set
up a 10 foot loop of wire (broken in the center) and connected it to a
150 watt 10kv DC supply. With a 1 megohm resistor in the middle of the
loop. I noted only about .1 guass mag field (near the limit of
discernment with the meter). The E-field near the wires was very weak
too (~1^10-11 coulomb). Next I took a ten meg resistor and the mag field
effectively went away. The E filed tripled around the wires. finally I
installed a 300 megohm resistor and the e field was every where - 10^-5
coulomb near the wire- (nearly an open). Needless to say the mag field
was just at a vanishing point.
It would appear that a macroscopic mag field capable of doing real
pondermotive work and a macroscopic E field capable of doing pondermotive
things are 100% mutually exclusive to conductive circuiry. They just are
not friendly to one another and will only be mutually present in tiny
amounts if equally potent. (whatever equally potent will mean to the
pensive mind). It seems that current, the producer of mag fields and
voltage the producer of E fields are not normally found in a wire
together.
When massive amounts of coulombs of charge are flowing in a wire to a
load (amps) they are locked down. Their work is totally magnetic in
nature. When potential exists on a wire with little or now coulombic
flow. the entire system, becomes a virtual "equipotential conductor" and
the coulombs due to potential are available to do ES things and work.
Your noting the coulombs being stuffed in the wire and pouring out as
they go in is a good anaology for the zero E field result. It must be
remembered, though, that if the electron is the only bearer of charge
then those electrons are not really in motion! It is just the perception
of their motion that is the coulomb flowing. I don't believe for one
minute that the physical particles are in motion from point A to point B
just the effective charge shuttling without the mass being in motion at
all. This leaves the question of disembodied charge open. Charge seems
to be able to be shuttle about in matter without the attendent motion of
the matter that bears that charge. I believe that only in the electron
tubes do we see electrons and their locked down charge in motion.
Richard Hull, TCBOR