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210 ⏐⏐⏐ PARALLEL CIRCUITS
I = 10 A
60 mA
I1 12 V
I 1
I 2
I 1
I 2
I 3
I 4
1 �
10 �
1 k�
100 k�
FIG. 6.90
Problem 24.
I
FIG. 6.92
Problem 26.
I 2
2.2 k�
12 V
R
FIG. 6.94
Problem 28.
2 �
6 �
(a)
I 1
1 A
8 � 56 �
I 2
FIG. 6.91
Problem 25.
*24. Parts (a), (b), and (c) of this problem should be done by
inspection—that is, mentally. The intent is to obtain a
solution without a lengthy series of calculations. For the
network of Fig. 6.90:
a. What is the approximate value of I1 considering the
magnitude of the parallel elements?
b. What are the ratios I1/I2 and I3/I4? c. What are the ratios I2/I3 and I1/I4? d. Calculate the current I1, and compare it to the result of
part (a).
e. Determine the current I4 and calculate the ratio I1/I4. How does the ratio compare to the result of part (c)?
25. Find the unknown quantities using the information provided
for the networks of Fig. 6.91.
I = 6 mA
I 1
I 2
2 mA
9 �
R
9 �
(b)
*26. For the network of Fig. 6.92, calculate the resistor R that
will ensure the current I1 � 3I2. *27. Design the network of Fig. 6.93 such that I2 � 4I1 and
I3 � 3I2. 68 mA
E 24 V
16 V
I 3
I 1 I 2 I 3
R 1 R 2 R 3
FIG. 6.93
Problem 27.
SECTION 6.7 Voltage Sources in Parallel
28. Assuming identical supplies, determine the currents I1 and I2 for the network of Fig. 6.94.
29. Assuming identical supplies, determine the current I and
resistance R for the parallel network of Fig. 6.95.
I
5 A
5 A
R 8 � 16 V
FIG. 6.95
Problem 29.
P