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Re: How many volts ?

This is not my strong suit (what is?) but let me take a stab since no one
else has responded.

I predict dV (between the plates) of 113 V = 100nC/.885nF. The +100 nC
plate will induce a -100 nC charge on the inside surface of the second
plate. That will leave a +90 nC charge on the outside surface. Between
the plates you can now teminate all the field lines from the positive
charges of Q2 but unlike the simple, equally charged capacitor, you will
have a considerable field outside the plates as the field lines from the
+90nC surface charge will head out towards infinity. That's my 'top of the
head' analysis.

Rick

----------
From: LUDWIK KOWALSKI <kowalskil@alpha.montclair.edu>
To: phys-l@atlantis.cc.uwf.edu
Subject: How many volts ?
Date: Monday, March 24, 1997 8:47 AM

What is a correct reasoning? What is the correct answer?
--------------------------------------------------------
AN ELECTROSTATIC PROBLEM

Two identical metallic plates (A1=A2 = area = 1 meter^2) are far away
from each other. Supported by isolated handles they are charged. The
first plate receives Q1=-10nC while the second receives Q2=+100nC.
Then the plates are moved toward each other and a capacitor is created.
The distance between parallel plates is 0.01 meter. Thus we know that
C=0.885 nF (vacuum). Predict the difference of potential, dV.
......................................................................
If the absolute values of Q1 and Q2 were equal then we would have
dV=Q1/C. But charges are different in this problem. How to calculate dV?
Ludwik Kowalski