Determine the capacitance of: (a) a 1-ft length of 35B/U coaxial cable, which has an inner conductor 0.1045 in in diameter, a polyethylene dielectric (ER = 2.26 from Table C.1), and an outer conductor which has an inner diameter of 0.680 in; (b) a conducting sphere of radius 2.5 mm, covered with a polyethylene layer 2 mm thick, surrounded by a conducting sphere of radius 4.5 mm; (c) two rectangular conducting plates, 1 cm by 4 cm, with negligible thickness, between which are three sheets of dielec- tric, each 1 cm by 4 cm, and 0.1 mm thick, having dielectric constants of 1.5, 2.5, and 6.