1. The problem statement, all variables and given/known data I have to find a electric field vector and a potential of the point in the origin of the x0y coordinate system (0,0) due to a longitudinal charge placed on a half circle as shown in the picture, with radius a. 2. Relevant equations Coulombs law. 3. The attempt at a solution Using Coulombs law: Vector E has two components: Which means E=Ey. Since dQ=Q'dl=Q'adθ If someone notices any mistakes up here, please point it out, since i haven't noticed any. Now, for potential: dl=dy because E has only y component, now when i integrate this i have V=∞, which seems wrong to me, so if someone knows how to solve this please post solution here.