LR circuits: Which of the following statements about inductors are correct? There may be more than one correct choice.
A) When it is connected in a circuit, an inductor always resists having current flow through it.
B) Inductors store energy by building up charge.
C) When an inductor and a resistor are connected in series with a DC battery, the current in the circuit is reduced to zero in one time constant.
D) An inductor always resists any change in the current through it.
E) When an inductor and a resistor are connected in series with a DC battery, the current in the circuit is zero after a very long time.

Question

Quizplus · Accepted Answer

Statement A is incorrect because an inductor resists changes in current flow, but once the current is established, it allows the current to flow through it without resistance.
Statement B is incorrect because inductors store energy in a magnetic field, not by building up charge.
Statement C is incorrect because the time constant for an LR circuit is L/R, and the current is reduced to 1/e (about 37%) of its initial value after one time constant, not reduced to zero.
Statement D is correct because an inductor opposes any change in current flow through it, whether increasing, decreasing, or reversing. This is due to the induced voltage that opposes the applied voltage.
Statement E is incorrect because the current in the circuit approaches, but does not quite reach, zero after a very long time. In the limit as time approaches infinity, the current approaches zero but never quite reaches it.

LR Circuits: Which of the Following Statements About Inductors Are