A metallic circular plate with radius r is fixed to a tabletop. An identical circular plate supported from above by a cable is fixed in place a distance dd above the first plate. Assume that dd is much smaller than r. The two plates are attached by wires to a battery that supplies voltage V. What is the tension in the cable? Neglect the weight of the plate. Express your answer in terms of the variables d, r, V, and constants ϵ0, pi. F=