Work done in E field

pic taken from sparkNotes, showing W = qV where V=Ed
Consider two points A and B , distance d apart along the E direction. Place a positive charge Q at A , if the force is towards B , then in moving from A to B , the charge will increase in velocity and we say the electric field does work on the charge. Work done QV= increase in KE . If the charge is moved to A from B, the force on the charge is still the same and work has to be done against this electric force. The formula remains very much the same, QV = increase in EPE = decrease in KE. Analogy: A stone falls from a height , workdone by the g field and the stone increase in ke. If you want the stone to rise up , there is loss in ke and this work done against weight is stored as gravitational potential energy. To handle a negative charge , be always aware of the force acting on it. The force on a negative charge is opposite to the E field vector. The force on a positive charge is in the same direction as the E field vector.