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162 ⏐⏐⏐ SERIES CIRCUITS S
I = 5 mA
E
– +
+ –
20 V
(a)
5 k�
R
P = 100 mW
FIG. 5.76
Problem 6.
+
16 V 2 k�
–
+ +
2 V
–
+
–
+
20 V
+
10 V
3 V
60 V
–
–
–
–
10 V
+
+
10 V
–
b a
V ab
(a) (b)
+ 6 V –
+
V 2
(a)
–
+
V1 –
FIG. 5.77
Problem 7.
24 V
FIG. 5.78
Problem 8.
*6. Find the unknown voltage source and resistor for the networks
of Fig. 5.76. Also indicate the direction of the
resulting current.
6 V
– + – 12 V +
– +
E
(b)
R
R
a
V ab
b
R2 = 5.6 k�
10 V 6 V
+
V 2
+ –
V1 R1 –
(b)
2.2 k�
Open
circuit
–
8 V
+
SECTION 5.4 Kirchhoff’s Voltage Law
7. Find Vab with polarity for the circuits of Fig. 5.77. Each
box can contain a load or a power supply, or a combination
of both.
8. Although the networks of Fig. 5.78 are not simply series
circuits, determine the unknown voltages using Kirchhoff’s
voltage law.