Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: Conserving Q ? /Faraday



I forgot to include some details in my last message, in case
somebody does want to verify our data.

1) Material was Lexan. But we know that all smooth dielectrics
display net charges. We no longer use handling threads; they were
very convenient but we decided to eliminate "another possible
contributor" to the irreproducibility. New lexan pieces were cut
with sticking handles.

2) Each measurement was made after 3 minutes at 1000 V. We discharge
the disectable capacitor, remove the top aluminum block and bring
pieces to the electrometer on another table, one after another. The
first sample is in the Faraday cup after about 25 seconds, the second
10 to 15 seconds later. (The rate of loosing charge is very slow, neither

A nor B loose more than 5 % of Q in couple of minutes. Clean the
"cork" of your old electrometer very well to arrive to this)

3) To measure C of the electrometer we first calibrated it in volts, using
our power supply. Then we charged it to V1=1000 V, connected it in
parallel to a known capacitor C2 (initially discharged) and measured
the new d.o.p. It was V2=540 V. Knowing that C2=2.1 pF ( a set of
parallel plates in the air), and assuming no charge was lost, we found
C=2.1*1000/(1000-540)=2.5 pF. This is plus or minus 10% or 20%, like
most data at this stage.

4) Prior to last set of data we had a long series of measurements in which
Q_B was positive and Q_A was negative. And Q_B was about two to
three time larger in magnitude than Q_A. This made us think that
things are more or less reproducible, qualitatively. The polarity was
consistent with the Faraday's model of ions pushing other ions away
from positive and negative electrodes. This may be the main effect
disturbed by other things. But who knows? Time will show.

Happy Thanksgiving to everybody.
Ludwik Kowalski