Page 174 - Schaum's Outline of Theory and Problems of Signals and Systems

CHAP. 31 LAPLACE TRANSFORM AND CONTINUOUS-TIME LTI SYSTEMS

(b)
Fig. 3-19

3.61. Consider the RC circuit in Fig. 3-20. The switch is closed at t = 0. The capacitor voltage before
the switch closing is u,. Find the capacitor voltage for t 2 0.
Ans. u,(t)=~,e-'/~~, 120

3.62. Consider the RC circuit in Fig. 3-21. The switch is closed at t = 0. Before the switch closing,
the capacitor C, is charged to u, V and the capacitor C, is not charged.
(a) Assuming c, = c, = c, find the current i(t) for t 2 0.
(b) Find the total energy E dissipated by the resistor R and show that E is independent of R
and is equal to half of the initial energy stored in C,.

Fig. 3-20 RC circuit.