You have a semicircle of radius R and charge Q. We also have available a test charge +qo.
Find the Magnitude and direction of the electric field at the origin.
F = k (Q * qo)/(R^2)
E = F/qo = kQ/R^2
The Attempt at a Solution
I'm not sure how to solve this, I assumed it would be kQ/R^2 but I am mistaken. Can someone please explain? I'm looking for an explanation on line but not having any luck