A semiquantitative treatment of surface charges in DC circuits

Surface charges play a major role in DC circuits because they help generate the electric field and potential distributions necessary to move the charges around the circuit. Unfortunately, it is generally regarded as a difficult task to determine the surface charge distribution for all but the simplest geometries. In this paper, we develop a graphical method for the approximate construction of surface charge distributions in DC circuits. This method allows us to determine (approximately) the location and the amount of surface charge for almost any circuit geometry. The accuracy of this semi-quantitative method is limited only by one's ability to draw equipotential lines. We illustrate the method with several examples. (C) 2012 American Association of Physics Teachers. [http://dx.doi.org/10.1119/1.4731722]