819_Physics ProblemsTechnical Physics

# 819_Physics - Chapter 28 P28.75 The total resistance between points b and c is 2.00 k 3.00 k R= = 1 20 k 2.00 k 3.00 k The total capacitance

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Chapter 28 159 P28.75 The total resistance between points b and c is: R = + = 200 300 120 .. . k k k k ΩΩ af . The total capacitance between points d and e is: C =+= 500 ... F F µµµ . The potential difference between point d and e in this series RC circuit at any time is: Ve e tRC t =− = −− ε 11 2 0 0 1 1000 6 . V . Therefore, the charge on each capacitor between points d and e is: + - a bc d e f S 120 V 2.00 k 3.00 k C 1 = 2.00 µ F C 2 = 3.00 µ F FIG. P28.75 qCV e e tt 1200 1 240 1 == = V C µµ bg and e e 22 1 360 1 = V C . *P28.76 (a) Let i represent the current in the battery and i c the current charging the capacitor. Then ii c is the current in the voltmeter. The loop rule applied to the inner loop is +− − = iR q C 0. The loop rule for the outer perimeter is −−− = iR i i r c 0. With i dq dt c = , this becomes −−+ = iR ir dq dt r 0. Between the two loop equations we eliminate i R q RC by substitution to obtain εε −+ F H G I K J += + + + + ++ + = Rr R q RC dq dt r R RC q dq dt r r q C Rr dq dt 0 0 0 This is the differential equation required. (b) To solve we follow the same steps as on page 875. dq dt R RrC q RrC
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## This note was uploaded on 12/14/2011 for the course PHY 203 taught by Professor Staff during the Fall '11 term at Indiana State University .

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