# Electrostatics: Moving Charge (comprehension problem)

I already know what the answer to this problem should be, however I do not understand why that is the case.

## Homework Statement

The negative charge (= -1 micro Coulombs) in the figure below goes from y = -5 to y = 5 and is made to follow the dashed line in the vicinity of two equal positive charges (= +5C). What is the work required to move the negative charge along the dashed line?

## Homework Equations

Vb - Va = Wab/q0
V = kq/r
F = qE
E = kq/r2
W = Fd cosine theta

## The Attempt at a Solution

Below is a representation of the arrangement of the charges. The horizontal dashes (-) are just space fillers and can be ignored, the vertical ones represent the negative charge's path.

------------y=5
-------------|
-------------|
-------------|
----+5C----y=0----+5C
-------------|
-------------|
-------------|
------------y=-5

I tried solving it on my own by taking the net displacement as 10 and coming to the conclusion that there would be work. Then I checked the answer and it said there is no net work because the force changes as the charge passes the origin. I don't understand why that is and was hoping someone could explain it to me. The only thing I could think of was that as the charge approaches the origin it is moving toward the positive charges (natural attraction) and as it moves past them it is moving away from the positive charges (against attraction).