What is the magnitude and direction of the electric field

[schern42]

What is the magnitude and direction of the electric field at a point midway between a -7.0 µC and a +6.0 µC charge 2.5 cm apart? Assume no other charges are nearby.

I thought I was approaching the problem correctly, but I'm not getting the right answer. I used the equation:
E = k(Q1 + Q2)/L^2

 

[Dick]

Hard to say what went wrong. What's L?

 

[schern42]

L is 2.5 cm

 

[Dick]

How far is the point midway between the charges from each charge? That's what should go into your E expression.

 

[rootX]

drawin it all might help, as it always does =P

 

[hage567]

Make sure all your units are consistent too.

 

[Dick]

It's better than plugging numbers randomly into formulas just because they happen to be stated in the problem.