17_Ch 20 College Physics ProblemCH20 Induced Voltages and Inductance

17_Ch 20 College Physics ProblemCH20 Induced Voltages and Inductance

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Induced Voltages and Inductance 191 20.44 The current in the RL circuit at time t is ( 1 t Ie R ) τ ε =− . The potential difference across the resistor is ( ) 1 t R VR I e ∆== − , and from Kirchhoff’s loop rule, the potential difference across the inductor is ( ) 11 tt LR VV ee εε −−  ∆=− ∆= =  (a) At 0 t = , ( ) () 0 1 R Ve 0 − = −= (b) At t = , ( ) ( ) 1 1 6.0 V 1 0.368 3.8 V R − = = (c) At 0 t = , 0 6.0 V L == (d) At t = , 1 6.0 V 0.368 2.2 V L = = 20.45 From ( ) max 1 t e II , max 1 t I e I If max 0.900 I I = at , then 3.00 s t = 3.00 s e 0.100 = or 3.00 s 1.30 s ln 0.100 Since the time constant of an RL circuit is = , the resistance is 2.50 H 1.9 1.30 s = 2
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This note was uploaded on 12/09/2011 for the course PHYS 2020 taught by Professor Staff during the Fall '10 term at FIU.

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