Figure 10: Three charged particles.Recall that the potential is related to the potential energy in the same way that the electricfield is related to the electric force. That is, we simply need to multiply the potential by the chargeto get the potential energy. If we choose infinity as our reference point for the potential (V∞= 0),then the potential of each of the point charges is:V=kqrFurthermore, since the electric force is a conservative force, the change in energy from infinityto the final location does not depend on the path taken. Since we chooseV∞= 0,U∞=q V∞= 0also. Hence, the final potential energy of the point charge gives the work done to get it there. Thepotential of of chargesq1andq2at the location ofQis:Vfin=khq12d+q2di= 0The final potential energy of chargeQis therefore:Ufin=Q Vfin= 0The total work done in moving the charge in from infinity to its current position is therefore 0.
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