Physics Book Solutions

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Unformatted text preview: es add; Ceq # C1 0 C2 0 % C # (b) From Figure 24.57c, Qtot # CeqV # (2.19 "10!6 F)(12.0 V) # 2.63"10!5 C. From Figure 24.57b, Qtot # 2.63 "10!5 C. Q4.8 2.63 " 10!5 C # # 5.48 V . U 4.8 # 1 CV 2 # 1 (4.80 " 10!6 F)(5.48 V)2 # 7.21" 10!5 J # 72.1 \$ J 2 2 C4.8 4.80 " 10!6 F This one capacitor stores nearly half the total stored energy. Q2 EVALUATE:! U # . For capacitors in series the capacitor with the smallest C stores the greatest amount of 2C energy. V4.8 # Figure 24.57 24.58. IDENTIFY:! Apply the rules for combining capacitors in series and parallel. For capacitors in series the voltages add and in parallel the voltages are the same. SET UP:! When a capacitor is a moderately good conductor it can be replaced by a wire and the potential across it is zero. EXECUTE:! (a) A network that has the desired properties is sketched in Figure 24.58a. Ceq # C 0 C # C . The total 22 capacitance is the same as each individual capacitor, and the voltage is spilt over each so that V # 480 V. (b) If one capacitor is a moderately good conductor, then it can be treated as a “short” and thus removed from the circuit, and one capacitor will have greater than 600 V across it. EVALUATE:! An alternative solution is two in parallel in series with two in parallel, as sketched in Figure 24.58b. Figure 24.58 24-16 Chapter 24 24.59. (a) IDENTIFY:! Replace series and parallel combinations of capacitors by their equivalents. SET UP:! The network is sketched in Figure 24.59a. C1 # C5 # 8.4 \$ F C2 # C3 # C4 # 4.2 \$ F Figure 24.59a EXECUTE:! Simplify the circuit by replacing the capacitor combinations by their equivalents: C3 and C4 are in series and can be replaced by C34 (Figure 24.59b): 1 1 1 # 0 C34 C3 C4 1 C 0 C4 #3 C34 C3C4 Figure 24.59b C34 # C3C4 . 4.2 \$ F /. 4.2 \$ F / # 2.1 \$ F # 4.2 \$ F 0 4.2 \$ F C3 0 C4 C2 and C34 are in parallel and can be replaced by their equivalent (Figure 24.59c): C234 # C2 0 C34 C234 # 4.2 \$ F 0 2.1 \$ F C234 # 6.3 \$ F Figure 24.5...
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This document was uploaded on 03/11/2014 for the course PHYSICS 240 at University of Michigan.

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