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The question is like this:
8 charges of magnitude q and different sighs are placed at corners of a cube of side a.
Find the work done in taking them far away from each other.
U = kq_{1}q_{2}/r
W = ΔU
First i found out the potential energy of a +q charge
U = 3kq^{2}/a + 3kq^{2}/√2a  Kq^{2}/√3a
and the same comes out to be for q charge (of course)
So for 1 charge,
W = U_{f}  U_{i}
W = 0  ( 3kq^{2}/a + 3kq^{2}/√2a  Kq^{2}/√3a )
W = 3kq^{2}/a  3kq^{2}/√2a + Kq^{2}/√3a
So work done for 8 charges = 8W ... Right?
But its wrong.
Some help please.
8 charges of magnitude q and different sighs are placed at corners of a cube of side a.
Find the work done in taking them far away from each other.
Homework Equations
U = kq_{1}q_{2}/r
W = ΔU
The Attempt at a Solution
First i found out the potential energy of a +q charge
U = 3kq^{2}/a + 3kq^{2}/√2a  Kq^{2}/√3a
and the same comes out to be for q charge (of course)
So for 1 charge,
W = U_{f}  U_{i}
W = 0  ( 3kq^{2}/a + 3kq^{2}/√2a  Kq^{2}/√3a )
W = 3kq^{2}/a  3kq^{2}/√2a + Kq^{2}/√3a
So work done for 8 charges = 8W ... Right?
But its wrong.
Some help please.
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