**Electric Potential Energy Due to Multiple
Charges:**

**A Numerical Example**

**That's all there is to it. Now let's try an example.**

**These charges are already in place:**

**How much work is required to bring in an additional charge
q? This additional charge q is located at x = 0.2 m, y = 0.1 m.
How much work is required to move this charge q in from infinity
to this location?**

**That is, What is the PE of charge q because the other Q's
are there?**

**Find the PE for the new charge q and each other charge Q;
then add up the sum (ordinary, scalar addition).**

**Electric Potential Engergy** -- like **any** form
of Potential Energy or **any** form of Energy or **any** form of work
-- is a **scalar**. There is do direction associated with work or energy.
The sum of the Potential Energy terms involves just an ordinary **scalar
equation**. That's easy; make use of it.

(c) Doug Davis, 2000; all rights reserved