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PROBLEM # 7.34 a) Use component values fromAppendix H to create a first-order RL circuit (see Fig. 7.16) with a time constant of 8 μs. Use a single inductor and a network of resistors, if necessary. Draw your circuit. R L R L L 1mH 1103 R 125 8 106 For a 125 Ω resistor, use a 100 Ω, a 15 Ω, and a 10Ω resistor in series. J1 V1 12 V R1 R2 R3 100Ω 15Ω 10Ω Key = Space L1 1mH b) Suppose an inductor you chose in part (a) has no iitial stored energy. At t = 0, a switch connects a voltage source with a value of 25 V in series with the inductor and equivalent resistance. Write an epression for the current through the inductor for t >= 0. J1 R1 R2 R3 100Ω 15Ω 10Ω Key = Space L1 1mH V1 25 V i (t ) i () [i (0) i()]e i (0) 0 25 i ( ) 0.2 A 125 i (t ) 0.2 [0 0.2]e 125 t 0.001 R t L 0.2 0.2e 125000t i (t ) 0.2 1 e 125000t A, t 0 c) Using your result from part (b), calculate the time at which the current through the inductor reaches 75 % of its final value. i (t1 ) (0.75)(0.2) 0.2(1 e 125000t1 ) 0.75 1 e 125000t1 0.25 e125000t1 ln(0.25) 125000t1 1.38629 125000t1 t1 1.38629 11 s 125000