2.5 Electric potential Let a charge Q be in a given electric field e. We want to move Q by a displacement dl. Then the work required against the electric force qe is QE Remember:-Q'E is the external force If the path is closed the total work done is ∮QE.dl First consider the field e generated by a point charge Q, e Qr1/4T Eor, then QQ W=-4T∈