Magnitude of Electric field at point P

[sambooby123]

Homework Statement

If Q=80nC, a=3.0m , and b=4.0m in the figure, what is the magnitude of the electric field at point P?

Homework Equations

EF=k*Q1*Q2 / R^2

The Attempt at a Solution

I'm not sure how to go about solving this problem. Do I use the above equation? I don't have the answer to the problem so I'm kinda in the dark about this. Thanks.

My answer is 46.78

 

[Delphi51]

Welcome to PF, Sambooby.
That formula you have is for force. You need to look up the one for electric field. You will have to use it three times to find the E field at P due to each of the charges. These fields will be in different directions, so you will have to add the vectors to find their total.