An 8.0-mH inductor and a 2.0- $\Omega$ resistor are wired in series to a 20-V ideal battery.A switch in the circuit is closed at time t = 0, at which time the current is zero.Immediately after the switch is thrown the potential differences across the inductor and resistor are:
A)0 V, 20 V
B)20 V, 0 V
C)10 V, 10 V
D)16 V, 4 V
E)unknown since the rate of change of the current is not given

Question

Quizplus · Accepted Answer

Immediately after the switch is thrown, there is no current flowing in the circuit. Therefore, there is no voltage drop across the resistor (Ohm's Law: V = IR), and the entire voltage of the battery (20 V) is applied across the inductor. Therefore, the potential differences across the inductor and resistor are 20 V and 0 V, respectively, making choice B the correct answer.

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