Electric field at origin, zero or nonzero?

[rcmango]

Homework Statement

Point charges +q and -q are placed at +50 cm and -50 cm on the x-axis, respectively. Is the electric field at the origin (halfway between the charges) zero or nonzero? If nonzero, which direction does it point?

Homework Equations

The Attempt at a Solution

If they were like charges, both positive, then I would say the electric field would be 0. I'm not sure because they are opposite polarities. Please help.

 

[antibrane]

Try to think of the electric field lines; if you drew them what would they look like?

 

[Winzer]

What would happen if I were to place a charge of -q at the origin?
How about +q? Would you agree that they would move? What does
this say?