A famous example of the method of image charges is a point charge above an infinite grounded plate. Can we use the method if the plate is not grounded?

My thoughts: The conductor's surface is equipotential otherwise the current starts to flow. And at the infinity we assume that potential must be zero. It means that an infinite not-grounded plate always have zero potential (with respect to a point at infinity)

  • $\begingroup$ "And at the infinity we assume that potential must be zero." - careful; for this, we ordinarily assume the system is bounded so that one can get arbitrarily far away. Consider, for example, the potential for an infinitely long wire with non-zero charge. $\endgroup$ Dec 3, 2016 at 2:24
  • $\begingroup$ no, the potential of the plate is non zero for any finite distance of the charge. $\endgroup$
    – Lelouch
    Dec 3, 2016 at 3:11
  • $\begingroup$ @Lelouch, non zero comparing to which point? $\endgroup$
    – Kirill
    Dec 3, 2016 at 10:56


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