For instance, if the work done by the electrostatic force due to a system of charges in bringing a charge of 10 C from some reference point B to a point A is 100 J, does this always imply that potential of point A is -10 V? I mean I could do the same amount of work (100 J) to bring the same charge from a point at 20 V to a point at 30 V, right? So, if the potential of a point is basically the change in P.E. (-WD by E.F.) per unit charge then the potential becomes independent of the reference point but that means bringing a charge from 20 V to 30 V, would make the potential of the final point as 10 V? Clearly, 30 V != 10 V. I am really getting confused here. Where am I wrong?


1 Answer 1


The best you can do is to find the potential difference between position $A$ and position $B$ ie the potential of position $A$ relative to the potential at position $B$.

The potential difference between position $A$ and position $B$ is independent of the position which you have chosen to have a potential equal to zero which you might call the reference position.

The potential at $A$ does depend on the position which you have chosen to have a potential equal to zero.

  • $\begingroup$ So you are saying I cant find potential of point A from the given variables? $\endgroup$ Sep 11, 2017 at 19:10
  • $\begingroup$ @AmyanshuJenamani If you say that the potential at a point is $+10\,\rm V$ that means that the potential at the point is $+10\,\rm V$ different from a point which has been defined as having a potential of $0\,\rm V$. $\endgroup$
    – Farcher
    Sep 11, 2017 at 19:16
  • $\begingroup$ So its all relative. I can assume any value of potential as long as the difference is constant and no definite potential of the reference point is given, right? $\endgroup$ Sep 11, 2017 at 19:21
  • $\begingroup$ @AmyanshuJenamani Yes potential is relative. $\endgroup$
    – Farcher
    Sep 11, 2017 at 19:24

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