alt.sci.physics

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< @ > wrote in message
news: @ ...
> On Sep 10, 1:19 am, "Don Kelly" wrote:
>
>> Magnetic conductor-certainly will have an effect-because it will have an
>> effect on the field in the vicinity of the conductor- I do not know
>> whether
>> this will increase or decrease the force but, as I said, I would expect a
>> miniscule increase. Reason indicates this much. The problem that I expect
>> is
>> that, in most cases, it falls within the margin of errors in
>> experimental
>> work and necessary approximations in theoretical analysis (calculations
>> from
>> theory will require approximations and y numerical field analysis).
>> As to the medium- think- what do you expect?
>>
>> No- I haven't done measurements-presently neither the resources nor the
>> desire. Neither have you. You have set up a number of artificial
>> proposals -why? do you have an alternative theory that gives different
>> results in these cases than conventional theory?
>
> YES. I need (and desire) to do experiments but I have no facilities,
> and
> you hane no idea and no desire to do experiments (being satisfied with
> the
> current theories) and have so facilities!
> My propositions are not baseless. I have an example:
> Some years ago during an article I proposed an experiment on just
> these
> same groups and someone performed the experiment. Let me quote a
> part of the postings here (you can search Google for the full postings
> in this
> respect):
>
> Considering the above-mentioned material it is shown that, contrary
> to the current belief, capacitance of a capacitor does not at all
> depend on the dielectric used in it and depends only on the
> configuration of its conductors.
>
> ....
>
> it is shown that
> contrary to what the current theory predicts, resonance frequency of
> a circuit of RLC will increase by inserting dielectric into the
> capacitor (without any change of the geometry of its conductors).
>
> ....
>
> That actually whether or not the resonance frequency of the circuit
> increases with inserting dielectric between the plates of the
> capacitor (without any change in the plates' configuration) is a
> quite practical test for establishing the validity of the theory
> presented in this article and invalidity of the current belief in
> this respect, or vice versa. Recently this experiment has been
> performed with a briliant success for the theory presented in this
> article showing specifically increase of the resonance frequency when
> inserting the dielectric. Here is the report of an electronics
> engineer who could not believe the result of his experiments in
> this respect:
>
> | Oh, yes, indeed the resonant frequencies do change as
> | drastically as you suggest if you put a dielectric with high
> | dielectric constant between the parallel plates of a capacitor.
> | I've put an example at the end of this posting.
> |
> | Example of capacitor with high-K dielectric...
> | You can buy "disc ceramic" capacitors with about capacitance.
> | These are nominally 1cm diameter, with nominally plate
> | separation, with dielectric only between the conductive plates.
> | The dielectric has a very high dielectric constant. If you resonant
> | such a capacitor with, say, a 5mH inductor, you will find its
> | resonant frequency will be about 70kHz. You can replace that
> | capacitor with one with the same plate size and spacing but air
> | dielectric, resulting in roughly capacitance. Then you will
> | find that the measured resonant frequency depends on the self-
> | resonance of the inductor, because you will be very hard-pressed to
> | make a 5mH inductor with self-capacitance as low as . If you
> | choose an inductor of, say, 1uH, properly constructed, then you
> | might reasonably see the effects of , but now you will be
> | dealing with much more awkward (especially if you have limited
> | access to good test equipment) resonant frequencies in the hundreds
> | of MHz. You will indeed find that the resonant frequency of that
> | inductor with the nominal ceramic-dielectric capacitor will
> | be on the order of 5MHz. The Q in each case should be high enough
> | (with a well-constructed inductor) to give an easily measured
> | resonant frequency. I _could_ do the experiment to specifically
> | demonstrate the _dramatic_ shift in resonance, and even use other
> | dielectrics less extreme, but I feel no need to: as I told you
> | before, I _routinely_ design resonant circuits and filters, even
> | taking into account the effects of stray capacitance and inductance
> | and the resistances of things like circuit board traces where
> | appropriate, and within my understanding of the tolerances of the
> | parts and the effects of the strays, I'm never surprised. I am
> | CERTAINLY never surprised by a resonance shifting higher as I
> | increase capacitance, so long as I'm within the practical range of
> | the parts I'm using.
> |
> | Note on 1uH coil: If you make a coil with #18AWG wire, which is
> | about diameter, and make that coil with uniformly spaced
> | turns, about diameter turns, spaced out total coil
> | length, it will have an inductance about , and its first
> | parallel self-resonance at about 190MHz. That implies about
> | effective self-capacitance. Adding an external capacitance
> | would drop the resonant frequency to about 145MHz.
>
>
> Regards,
> Hamid V. Ansari
----------------------
The quoted material indicates a higher frequency with a smaller
capacitor-look at the numbers- (resonance shifting higher as capacitance
increased is probably either a typo or a factor due to the coil internal
capacitance )-guess what- that doesn't contradict present theory.
May I also point out the the relation of capacitance to the dielectric
material was established from experiments carried out over the last 100 or
so years. It's been tested. In fact putting a dielectric in a parallel
plate capacitor and measuring the change in capacitance is one way to
measure relative permittivity.

So -what's your point.?
Over and out.

--

Don Kelly dhky@
remove the X to answer

>