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700 ⏐⏐⏐ SERIES AND PARALLEL ac CIRCUITS
e = 7.07 sin qt
E = 5 V ∠ 0°
E = 120 V ∠0°
+
–
+
e = �2(10) sin qt
–
I
Z T
Z T
R
+ VR –
R
1 k�
FIG. 15.131
Problem 21.
+ VR –
R
100 �
FIG. 15.132
Problem 22.
Z T C
L
1 k� 20 mH
FIG. 15.133
Problem 23.
+
E = 120 V ∠ 0°
–
I = 3 A ∠ v
+
L 20 mH V L
–
+
C 0.5 mF V C
–
2 �
FIG. 15.130
Problem 20.
+
8 nF VC –
a c
*20. Find the series element or elements that must be in the
enclosed container of Fig. 15.130 to satisfy the following
conditions:
a. Average power to circuit � 300 W.
b. Circuit has a lagging power factor.
?
SECTION 15.5 Frequency Response of the
R-C Circuit
*21. For the circuit of Fig. 15.131:
a. Plot ZT and vT versus frequency for a frequency range
of zero to 20 kHz.
b. Plot VL versus frequency for the frequency range of
part (a).
c. Plot vL versus frequency for the frequency range of
part (a).
d. Plot VR versus frequency for the frequency range of
part (a).
*22. For the circuit of Fig. 15.132:
a. Plot Z T and v T versus frequency for a frequency range
of zero to 10 kHz.
b. Plot V C versus frequency for the frequency range of
part (a).
c. Plot v C versus frequency for the frequency range of
part (a).
d. Plot V R versus frequency for the frequency range of
part (a).
*23. For the series R-L-C circuit of Fig. 15.133:
a. Plot Z T and v T versus frequency for a frequency range
of zero to 20 kHz in increments of 1 kHz.
b. Plot V C (magnitude only) versus frequency for the
same frequency range of part (a).
c. Plot I (magnitude only) versus frequency for the same
frequency range of part (a).