The central charge for the Seiberg-Witten low-energy effective Action is computed using Noether supercharges. A reliable method to construct supersymmetric Noether currents is presented. PACS numbers: 11.30.Pb , 11.30.-j , 12.60.Jv , 11.10.Ef The electromagnetic duality of Seiberg-Witten [1] relies heavily on the BPS mass-formula M = |Z| where Z = (nea+ nmaD) (1) is the topological central char...