Problem 1.15 The plot in Fig. P1.15 displays the cumulative amount of charge q(t ) that has entered a certain device up to time t . What is the current at (a) t = 1 s (b) t = 3 s (c) t = 6 s
t 6s 8s
Figure P1.15: q(t ) for Problem 1.15
Determine currents I1 to I4 in the circuit of Fig. P2.17.
I1 2 I2 4 6A I3 2 I4 4
Figure P2.17: Circuit for Problem 2.17.
Solution: The same voltage exists across all four resistors. Hence, 2I1 = 4I2 = 2I3 = 4I4 . Also, KCL mandates that I1 +
Apply nodal analysis to determine Vx in the circuit of Fig. P3.2.
2 1 V 3A 2 + 4 Vx _
Figure P3.2: Circuit for Problem 3.2.
Solution: At node V , application of KCL gives V V 3+ = 0, 2+1 2+4 which leads to V = 6 V. By voltage division, Vx = V
Problem 2.34 Solution:
Find Req at terminals (c, d ) in the circuit of Fig. P2.33.
3 3 6
5 12 6 5
c Req d
5 4 5
c Req d
Req = 4 + 5 + 5 = 14 .
Problem 2.35 Simplify the circuit to the right of terminals (a, b) in Fig. P2.35 to nd Req , and