A lower bound for electrostatic capacity in the plane
Ludwig Edward Fraenkel · Proceedings of the Royal Society of Edinburgh Section A Mathematics · 1981
Synopsis This note presents a lower bound, in terms of the diameter ratio of the inner and outer conductors, for the electrostatic capacity of certain two-dimensional condensers. We use double Steiner symmetrization to prove that the minimizing condenser consists of a line segment placed symmetrically within a circle; the capacity of this condenser is known explicitly.