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Re: TC Electrosattics Revisited II


From: 	John Berry[SMTP:antigrav-at-ihug.co.nz]
Sent: 	Thursday, September 11, 1997 7:12 PM
To: 	Tesla List
Subject: 	Re: TC Electrosattics Revisited II

Does this help?

>From : Essentials of electromagnetism

The proportionality constants km and ke in the laws expressed by (1.1) and
(1.2) can be fixed only when a unit of electric charge is decided upon. It
would be quite natural to choose a unit of charge that makes ke equal to one.
Since electric charge and electric current are directly related, no choice
remains for the proportionality constant km. In the early history of
electromagnetism this connection between the electric and magnetic forces was
not appreciated. A confusing duplication of unit systems then developed by
assigning values to both ke and km independently. The electric units for charge
and current, based on (1.1), were then different from the corresponding
magnetic units based on (1.2). Further confusion arose by the use of other
practical units, having a size considered more suitable for measurement
purposes.
 This confusion of electromagnetic units was a powerful impetus to the
development of modern SI units based on the use of metres, kilogrammes and
seconds rather than centimetres, grammes and seconds as in earlier systems. In
SI units, electric charge is regarded as a new basic physical entity whose unit
is the coulomb (C). Electric current is then measured in the unit of the ampere
(A), which is equal to the passage of one coulomb per second. In practical
situations, electric current can be measured much more accurately than electric
charge. For this reason the choice has now been made to define the constant km,
leaving ke to be determined empirically. By international agreement:

"A constant current of one ampere maintained in two parallel, infinitely long,
straight conductors of negligible cross-section separated by one metre in
vacuum, produces a force between these conductors of 2 x lO-7 newtons per metre
of length."

 After fixing the value of km in this way, it is usual in SI units to express
(1.2) as

If anyone wants to hear the rest please reply.


Tesla List wrote:

> From:   Greg Leyh[SMTP:lod-at-pacbell-dot-net]
> Sent:   Wednesday, September 10, 1997 3:43 PM
> To:     Tesla List
> Subject:        Re: TC Electrosattics Revisited II
>
> Richard Hull wrote:
>
> [snip]
> > It is important to note that the electrostatic coulomb and the
> > electrodynamic coulomb (as defining current) are different beasts.  The
> > 1 ampere coulomb for electrodynamics is the "effective passage of
> > relative charges" and not the real passage of electrons.  The coulomb
> > of static electricity is real held charge represented by static charge
> > units.
> >
> > One coulomb of electrostatic charge has the potential for vastly more
> > effective work than one ampere flowing in a circuit.
>
> Surely that depends upon the L's and C's involved!!! Consider this example:
>
> For inductors,  E = 1/2 LI^2
> For capacitors, E = 1/2 CV^2
>
> Since V = Q/C, E = 1/2 Q^2/C for capacitors as well.
>
> Compare the energy stored in a 10 Farad capcitor with 1 coulomb of charge,
> vs. the energy stored in a 10 Henry inductor with 1 Ampere of current.
> >From the above equations:
>
> Ecap = 0.05 Joules.
> Eind = 5.00 Joules.
>
> > The electrostatic
> > unit concerns itself with scalar potential or voltage, while the other
> > value links the coulomb to current in metallic circuits only with no
> > voltage equivalence.
> >
> > Richard Hull, TCBOR
>
> This whole 'coulomb equivalence' thing is starting to sound like
> 'urban lore', as I have not met anyone _outside_of_this_List_ who
> has ever heard of such a thing.  Are you guys funnin' with me?
>
> -GL