On Fri, 27 Jun 2008 06:35:23 -0700 (PDT), blackhead
<larryharson@[EMAIL PROTECTED]
> wrote:
>On 26 Jun, 03:25, John C. Polasek <jpola...@[EMAIL PROTECTED]
> wrote:
>> On Wed, 25 Jun 2008 18:32:46 GMT, "Bill Miller"
>>
>> <billmillerkt...@[EMAIL PROTECTED]
> wrote:
>>
>> >"Timo A. Nieminen" <t...@[EMAIL PROTECTED]
> wrote in message
>> >news:Pine.WNT.4.64.0806240535450.1160@[EMAIL PROTECTED]
>> >> On Mon, 23 Jun 2008, Bill Miller wrote:
>>
>> >That leaves hordes of non PG students still believing this rubbish.
And it
>> >begs the question of why, in UG cl*****, the instructors don't say
>> >*something* about how theses two parameters don't cause each other,
but that
>> >they always appear simultaneously. I suspect its because the
instructors
>> >don't know it!
>>
>> I fervently hope you're not teaching anyone. You're too ignorant to be
>> in the business of physics which is that of discerning cause and
>> effect. Instead of denying cause and effect, you should be analyzing
>> for the underlying science.
>>
>>
>>
>> >Is there a single UG EM textbook that correctly categorizes the
relation****p
>> >between E and H? Even ONE?
>>
>> Tell us, omniscient one, what exactly what is this precious
>> relation****p, of which you are evidently the exclusive franchisee?
>>
>> Here's how I think it works: Volts applied to a coil build up H
>> ampturns/meter which when multiplied by mu store momentum B in
>> webers/m^2. Upon opening the circuit, momentum B divided by mu
>> generates a sizeable voltage back at the original terminals. The field
>> B is successively the sink and the source. Yes V causes B and B causes
>> V.
>>
>> >Cheers, Bill
>>
>> John Polasek
>
>A charge is the source of E and H which are orthogonal and propagate
>independently from it as given by the Lienard-Wiechert field
>equations. I think that's all Bill is saying which isn't wrong, is it?
You are right; retardation is adequately represented by the
Lienard-Wiechert field, which I also see referenced in my 1962
Panofsky Philips. They are much cleaner and simpler than Jefimenko's
which can be seen in Wiki.
For Lienard, yes, if you postulate a moving charge it will have
complex field effects. But in free space the only current J would be
Ddot and there is no overt charge density to put in Jefimenko's
equation.
This topic is of little practical effect, retardation being a very
slippery item, and there is enough other disinformation going around
to bother with these sophomoric maunderings.
For example, it is unconscionable that there are physicists today
still embedded in cgs, a legacy from their professors with these
consequences:
1. They have given up the coulomb in favor of the esu.
2. It is not possible to assign units to equations e.g.:
D = E please, assign units
3. they gave up capacitance which should be coulomb/volt (or
farads) in favor of
4. capacitance in centimeters, a clue to the naive "peas on a
knife" view of electrostatics.
5. It is not possible in cgs to intelligently discuss a vacuum
capacitor.
Enough. More dismal is the idea that most students do not even know
the difference between cgs and rmks or SI which have assigned the
properties of eps0 and mu0 to the vacuum.
The main idea is that there are forces that can store energy in the
vacuum which energy then turns around and becomes a source itself in a
completely reciprocal fa****on. And this, without the intervention of
charges.
John Polasek
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