Re: conserving Q ? / Faraday

[Ludwik Kowalski <kowalskiL@MAIL.MONTCLAIR.EDU>]

Brian asked about sizes of lax sheets.
Each lexan sheet is 6 by 7 cm and 0.3 (+/- 0.05) mm thick.

The home-made electrostatic electrometer (see below) works. I just
tried it using 0.13 gram washer suspended by the thread soaked in
the colloidal solution of carbon in alcohol (candle soot would also
work). It was suspended (L=6 cm) between two vertical copper
plates separated by 4.5 cm. One plate was grounded, another was
connected to +3000 V. The washer, initially in the middle, was
displaced by an angle of perhaps 15 degrees when 2000 V was applied
to it via the thread. Grounding the thread brought the washer to the
initial position.

I did not try placing the Faraday cup on the thread-supporting
platform; it was only a "quick and dirty" test of an idea, not a
replacement for the gold leaf electrometer. The sensitivity of the
"voltmeter" did increase at +4000 V between plates, as anticipated.
Ludwik Kowalski

> Instead of a gold leaf electrometer you may consider a "pithball"
> suspended in a uniform electric field by a conducting thread and
> connected to the Faraday cup. This electrostatic voltmeter may be
> more convenient than the gold leaf. No separate measurement of
> polarity will be necessary, the suspended piece will turn left or
right
> from the equilibrium, according to the sign of the charge inside the
> Faraday cup. Knowing the weight (and E) you will be able to calculate
> coulombs from the angle. And sensitivity will be under your control.