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PROBLEMS
SECTION 15.2 Impedance and the Phasor Diagram
1. Express the impedances of Fig. 15.113 in both polar and
rectangular forms.
L = 2 H
R = 6.8 Ω
ω = 377 rad/s
(a) (b) (c)
ω = 377 rad/s
f = 10 kHz
(d) (e) (f)
L = 0.05 H
f = 50 Hz
C = 10 µ F
C = 0.05 µ F
R = 200 Ω
2. Find the current i for the elements of Fig. 15.114 using
complex algebra. Sketch the waveforms for v and i on the
same set of axes.
i
i
R = 5.1 k�
R
+
3 �
–
v = 21 sin(qt + 10°)
(a)
v = 4 � 10 –3 +
sin(qt – 120°)
–
(d)
i
i
X L
L = 0.1 H
3. Find the voltage v for the elements of Fig. 15.115 using
complex algebra. Sketch the waveforms of v and i on the
same set of axes.
i = 4 � 10 –3 sin qt
R 22 �
(a)
+
v
–
FIG. 15.113
Problem 1.
+
7 � v = 49 sin(qt + 70°)
–
+
(b)
v = 16 sin(377t + 60°)
–
(e)
FIG. 15.114
Problem 2.
i = 1.5 sin(377t + 60°)
L
(b)
FIG. 15.115
Problem 3.
+
0.016 H v
–
ω = 157 rad/s
i
i
X C
C = 2 mF
PROBLEMS ⏐⏐⏐ 695
+
100 �
–
(c)
+
v = 120 sin qt
–
(f)
i = 0.02 sin(157t + 40°)
C 0.05 mF
(c)
v = 25 sin(qt – 20°)
+
v
–
f = 5 kHz