Inductors & DC Transients (Mixed)
In the circuits (a) and (b) switches S1 and S2 are closed at t = 0 and are kept closed for a long time. The variation of currents in the two circuits for t 0 are roughly shown by (figures are schematic and not drawn to scale):

Show answer and solution
Answer: (a)
- Circuit (a), R-C: the uncharged capacitor acts as a short at , so at first and then decays as to zero.
- Circuit (b), L-R: the inductor stops a sudden current, so at and then grows as to .
- So the answer is (a): curve (a) decays from , curve (b) rises to .