1. The problem statement, all variables and given/known data Charge Q is uniformly distributed around the perimeter of a semicircle of radius R. What is the electric field at the circle's center? 2. Relevant equations E=kQ/R^2 3. The attempt at a solution λ=Q/(∏R) ∫(kλ)/R^2 dθ from 0 to pi and get the answer to be (kQ)/R^3 or is it ∫(kλ)θR/R^2 dθ from 0 to pi and get (kλ∏^2)/2R The second one I was trying to put the arc length in, but I'm not sure if you need to or not.