Two identical capacitors A and B are charged to the same potential V and are connected in two circuits at t = 0 as shown in figure. The charges on the capacitors at a time t = CR are, respectively,

Question

Philoid · Accepted Answer

The p side of the p-n junction diode is at higher potential than the n side and hence the diode is forward biased in figure (a). Assuming ideal diode case, the diode is treated as short circuit. The figure (a) network thus becomes a series source free RC circuit. The voltage equation in source free series RC circuit is given by

At t=0,

At t=RC,

Since, the charge is given by.

At t=RC, the charge is

The diode in the figure (b) is reverse biased since its p side is at low potential than its n side. Assuming ideal diode case, the diode is treated as open circuit in figure (b). Thus the charge on the capacitor at all times is

Therefore, the correct answer is option B.