- #1

Seung Tai Kang

## Homework Statement

Two point charges Q1= +5.00 nC and Q2 = -3.00 nC are separated by 35.0cm. What is the electric potential at a point midway between the charges?

## Homework Equations

V = Ke(q/r), PE = Vq[/B]

## The Attempt at a Solution

This question is from Serway textbook. The answer is 103J/C. I understand the answer was obtained by Ke(5 nC- 3 nC)/ 17.5cm. But I wonder why do we subtract the two? Shouldn't we add them? For example, if +1charge were put at the mid point, the charge would feel both repelled and attracted by positive and negative charges, hence the summative force of the two. But the answer tells that the charge would have the potential energy that is partially canceled out.

Last edited by a moderator: