# RE: Variable Capacitance and Inductance

```Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Dave,

At 08:31 AM 5/25/2002 -0500, you wrote:
>
>The reason for using the classic formula as a reference point is because
>inductance is defined in that equation.  In the classic inductance equation
>inductance is defined as a specific set of physical characteristics of a
>physical coil with regard to permeability of free space.  Obviously the
>classic formula is not accurate because there is some other force acting on
>the inductance of the coil.  Wheeler's formula empirically accounts for this
>force, but does not define it.  Since science is about finding out all the
>details of how our universe works, it would be good to identify this force
>that deviates the coil's actual inductance from the formula that defines
>inductance.

"Modern" equtions and methods account for the errors in that often cited
formula.  Trying to use it today is of no value other than teaching student
how to apply Maxwell's equation to a coil.  It is really a bad example, but
a good example would be too complex for the purpose.  That old formala has
nothing to do with the definition of inductance but it is just a poor
example of how to use the difinitions.

>
>It may be this was tried before, but folks weren't aware of the EMF effect
>that you and Paul have identified and quantified.  Undoubtedly there are
>numerous minor forces that affect coil inductance, but after the EMF, earth
>proximity must be the largest factor.  Wheeler's formula, while it does
>yield a close approximation of the inductance of a coil, does not define
>inductance per se.  Besides proving a definition of coil inductance,
>identifying a constant of inductive reactance imparted by the earth would
>have significant scientific usefulness.  It could get you a science prize,
>as the knowledge could be put to commercial use.

But the modern equations work perfectly fine without the Earth's effects.
Indeed, since those equations work so well, it shows how trivial other
effects are.  There are well known ground plane effects and all that, but
nothing new there...  Jim mentioned relativistic effects but that is
getting too weird...  We can also calculate the electrostsic effects
between a fly an Earth and a fly in a far off galexy...  But that is
getting silly...

>
>
>The distances Tesla raised the ball from the earth were in something like 20
>feet increments.  Twenty feet is a lot of extra space and a lot of extra
>influences can get between the ground and ball.  These extra influences are
>likely from stray magnetic flux from various sources.  This needs to be
>proved, but it is a real possibility.  The fact that Tesla measured the
>capacitance variations that he did is reason enough to look into stray
>magnetic flux or other possible increases in the dielectric field strength.

So Tesla's tests could have a lot of interfeerence error :-(  Atmospheric
electrity, AC hum, sun spots...   That stuff is not the raised sphere's
problem.  That's the exact problem with Tesla's old data, one does not know
what in the world he was really measuring and we can't query him to
determine the details.  Other than being an interesting account, the "data"
cannot be trusted to support any facts drawn from it.  It would have to be
reproduced today with trusted equipment where the details are known or
could be determined.  Then the results could be beleived and trusted.

>
>Excellent point, Terry.  Just as we stand on the shoulders of geniuses, we
>can also step on the backs of those who fall. (sounds sick but it's true.)

They don't really fall.  Like TV shows there back again nest week...

>
>
>>We like a good fight :o)))  And it makes winning sweeter ;-))  However,
>watch your back since every champion has a challenger...
>
>Is this Fight Club?  Sounds like fun.

Fun for the winner...  I see Paul just delivered a good knockout punch  =:o<

>
>
>>We cannot trust Tesla's original data for sphere elevation vs. capacitance
>
>>The tables like on pages 209/210 would evoke wild laughter from the
>audience as they carried our beaten carcasses out :o))
>
>I'm ready to look at this with you.  What in particular do you have a
>problem with?  I think it is very insightful as to how he carried out his
>experiment.

What would be needed is a clear table for values of the 30 inch sphear's
elevation vs. capacitance with the wire there.  Like this:

Elevation (feet)	Capacitance (pF)
5			2.3
10			3.4
15			4.5
20			5.6
.			.
.			.
.			.

This should show a smoothly increasing capacitance (jitter in the data
could be used to estimate error).  Such a simple plain table of Tesla's
data is basic and could be tested, experimentally reproduced, and proved or
disproved...  It could easily be looked at to determine if something
unexpected were occuring and if it could be reproduced today or would have
to be discounted as expreimental error in the original test.  This is the
most simple, basic, and needed data Tesla would have to provide today to
support his observation.  Without it, we have nothing but arguments over
data that does not exist...

Cheers,

Terry

```