# a point charge above an infnite not-grounded plate

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)

• "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. Dec 3, 2016 at 2:24
• no, the potential of the plate is non zero for any finite distance of the charge. Dec 3, 2016 at 3:11
• @Lelouch, non zero comparing to which point? Dec 3, 2016 at 10:56