Solutions 275across the capacitor does not change. Hence current
does not flow, and UcD is zero. Finally, during
the time interval from 3t 0 to 5t 0 , the capacitor is
discharged, the current through the resistor is
negative and constant, and its magnitude is halfUCB(^54) 5to t
to 2t 0
Fig. 221
the value of the current during the time interval
from t 0 to 2t 0.
3.43. Before switching the key K, the charge on
the capacitor is
41 =
the positive charge being on the lower plate, and
the negative charge, on the upper plate.
After switching the key K, as a result of re-
charging, the upper plate will acquire a positive
charge, and the lower plate a negative charge equal
to
43 = W2C.
Thus, the current source of emf W 2 will do the
workW 2 (q 1 q 2 ). The required amount of heat
liberated thereby in the resistor is
Q= (41+ q2)-
4i 1 C (el ± W2) 2
— 2C J 2 •
3.44. Let us determine the current passing through
the current source in the circuit:
/ — (Ri + R2)
r RiR2/(Ri+ R2) r (R1-F-Rz)-F Rifiz
18*