The electrostatic potential or voltage between two points is defined as the energy (work) required to move a small charge through an electric field between the two points, divided by the size of the charge. If there is an electric field directed from point formula_1 to point formula_2 then it will exert a force on a charge moving from formula_2 to formula_1. Work will have to be done on the charge by a force to make it move to formula_1 against the opposing force of the electric field. Thus the electrostatic potential energy of the charge will increase. So the potential at point formula_1 is higher than at point formula_2. The electric field formula_8 at any point formula_9 is the gradient (rate of change) of the electrostatic potential formula_10 :