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isolated conductors

Subject: isolated conductors
  Date: Wed, 28 May 97 09:39:43 EDT
  From: person-at-ggone.ENET.dec-dot-com
    To: tesla-at-pupman-dot-com
        

>> I have always found that any isolated capacitance when considered
>>as a capacitive device and connected to or near enough to another
>>capacitive isolated device forms a simple series capacitive circuit
>>(with reference to gorund).  This makes the large device appear to
>>possess less than its full isotropic capacitance with reference to
>>ground, which is where we always reference most isolated isotropic
>>capacitive measurements on earth.
        [hand wrapped to foil the line chop bug.]

>Now I'm really confused. As a sphere is moved away from ground its
>capacitance goes up?
        Don't see that that was said.

>As a second sphere is brought closer to one being measured, the
>capacitance goes down?
        Specific case cited (paraphasing):
        "...they form a SERIES CIRCUIT...",
        in which case the capcitance would decrease.  {I'm not so sure
        that it alwasy happens, I'd expect it to depend on the
        physical arrangments of the two conductors.)

>Even a series circuit to the second capacitor is in parallel
        Seems to me this depends on the physical arrangment of the
        conductors.  (The discussion was about conductors (one
        electrode) not capacitors (two electrodes plus dielectrics).

        Once the elements are no longer conductively linked, there are
        not neat, 'circuits' to be in 'series' or 'parallel' as near
        as i can tell.

==============================
>> In the extreme, the experiments could prove fatal.

>I had wanted to tie a weather baloon to a long tether just to let it up
>and anchor it. Youre saying that if the baloon were conductive and the
>tether also you would get a voltage to ground?
        Plan on it.  Expect it.  _don't_ complete the ground path
        thru 'you'  (or any instrument of value).  (Dry rope is a
        fairish insulator.  WET rope, or metal cable isn't....)  Even if
        the ballon is not conductive, the ropes end is at the same
        high altitude, so the bottom can get 'hot' if the 'rope' is
        conductive.

        regards
        dwp