College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 61

Consider a plane parallel-plate capacitor made of two strips of aluminum foil separated by a layer of paraffincoated paper. Each strip of foil and paper is 7.00 cm wide. The foil is 0.004 00 mm thick, and the paper is 0.025 0 mm thick and has a dielectric constant of 3.70. What length should the strips be if a capacitance of 9.50 × 10 8 F is desired (If, after this plane capacitor is formed, a second paper strip can be added below the foil-paper-foil stack and the resulting assembly rolled into a cylindrical form-similar to that shown in Figure 16.26-the capacitance can be doubled because both surfaces of each foil strip would then store charge. Without the second strip of paper, however, rolling the layers would result in a short circuit.)