# Conceptual problem regarding parallel plate conductors

1. Apr 24, 2012

### kartikeya95

1. The problem statement, all variables and given/known data

if two plates are kept parallel P1 and P2. one has a charge (q)..the outer surface of this plate has a charge lets say (x) thus the inner surface has a charge (q-x)..this (q-x) induces an opposite charge -(q-x) on inner surface of P2. the outer surface of P2 is grounded.

Why are the charges on outer surfaces of both the plates taken to be zero?

3. The attempt at a solution

(q-x) and -(q-x) are bound charges. ∴ the only charge that will be grounded will be the charge existing on the outer surface of P2. since the field between the two conductors has to be zero ∴we can use the expression for field and the following is the result.

x/2εA + q-x/2εA = q-x/2εA + 0/2εA

this gives x=0...therefore both the charges on the outer surface are zero

Last edited: Apr 24, 2012