1. The problem statement, all variables and given/known data Positive charge Q is uniformly distributed around a semicircle of radius a. Find the magnitude of the electric field at the center of curvature P. Express your answer in terms of the given quantities and appropriate constants. 2. Relevant equations 3. The attempt at a solution So here is my thinking. The charge per unit length of the circle would be Q/(a*pi) because a*pi is the arc length of the semi-circle. Next I assumed that the x-component is zero due to symmetry so I only need to calculate the force in the y direction. Therefore the magnitude of the electric field created by each point on the circle at the origin would be kQ/(a^2 * pi * a). The y-component of that electric field would be sin(theta)kQ/(a^3 * pi). I integrated this from theta = 0 to pi and the answer was 2kQ/(a^3 * pi). Where did I go wrong?