At 09.40 2014.12.14, Sean Breheny wrote:
>I didn't read the entire stackexchange posting but I suspect that the
>threshold and subsequent decreasing voltage has something to do with stray
>capacitance in  the measuring set-up and also possibly capacitance between
>the setup and earth. Your voltmeter/electrometer has some tiny internal
>capacitance plus capacitance between its leads. This is in parallel with
>the test capacitor. As the voltage increases, some of the charge in the
>test capacitor is transferred to the parasitic capacitance. When the test
>capacitance begins to approach the value of the parasitic capacitance, the=
n
>the voltage will no longer be able to increase much because increasing
>voltage would require more charge to be transferred to the parasitic
>capacitance.

By the way, I've read somewhere that the Earth has about 400 uF capacitance=
..

How could I use the Earth capacitance in an experiment?

When I was a kid I tried to see if current flowed when I put a battery pole
on Earth, but I could measure no current.

Yes of course to see a current there must be flow back, but I thought that
the Earth was so almighty and huge that my battery's electrons would try to
travel towards that route, and before they came back to me saying (there's
no flow of current possible) they had to reach the other end of the world. =
:)

Have a nice sunday,
Mario

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