A question

The diagram above shows part of a circuit consisting of an inductor, a resistor, and a capacitor in series.
At the instant shown the current in the circuit is 2 A, and it is decreasing at the rate of 0.2 A/s. The capacitor voltage is 5 volts, with the positive plate on the right.
The inductor has an inductance of L = 5 H, and negligible resistance.
The resistor has a resistance of R = 2 W.

What is the magnitude of the potential difference across this series combination at this instant?

  1. 0 V
  2. 2 V
  3. 8 V
  4. 10 V
  5. None of the above















The voltage across the inductor is 1 V, and that has the same polarity as the capacitor voltage, so those two combine to 6 volts. The voltage across the resistor is 4 V, with the opposite polarity, so the net potential difference has a magnitude of 6 - 4 = 2 V.