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1120 ⏐⏐⏐ PULSE WAVEFORMS AND THE R-C RESPONSE
vi 20 V
T 2
T
–20 V
v i
20 V
f = 500 Hz
0 T T
t
2
FIG. 24.61
Problem 22.
SECTION 24.6 R-C Response to
Square-Wave Inputs
20. Sketch the voltage vC for the network of Fig. 24.60 due
to the square-wave input of the same figure with a frequency
of
a. 500 Hz.
b. 100 Hz.
c. 5000 Hz.
+
v i
–
R
5 k�
FIG. 24.60
Problems 20, 21, 23, 24, 27, and 28.
t
i c
+
C 0.04 mF vc –
21. Sketch the current iC for each frequency of Problem 20.
22. Sketch the response vC of the network of Fig. 24.60 to
the square-wave input of Fig. 24.61.
23. If the capacitor of Fig. 24.60 is initially charged to 20 V,
sketch the response vC to the same input signal (of Fig.
24.60) at a frequency of 500 Hz.
24. Repeat Problem 23 if the capacitor is initially charged to
�10 V.
SECTION 24.7 Oscilloscope Attenuator and
Compensating Probe
25. Given the network of Fig. 24.42 with Rp � 9M�and Rs �
1 M�, find Vscope in polar form if Cp � 3 pF, Cs � 18 pF,
Cc � 9 pF, and vi � �2�(100) sin 2p10,000t. That is,
determine Zs and Zp, substitute into Eq. (24.8), and compare
the results obtained with Eq. (24.10). Is it verified
that the phase angle of Zs and Zp is the same under the
condition RpCp � RsCs? 26. Repeat Problem 25 at q � 10 5 rad/s.
SECTION 24.9 Computer Analysis
PSpice or Electronics Workbench
27. Using schematics, obtain the waveforms for vC and iC for
the network of Fig. 24.60 for a frequency of 1 kHz.
*28. Using schematics, place the waveforms of vi, vC, and iC on the same printout for the network of Fig. 24.60 at a
frequency of 2 kHz.
*29. Using schematics, obtain the waveform appearing on the
scope of Fig. 24.37 with a 20-V pulse input at a frequency
of 5 kHz.
*30. Place a capacitor in parallel with Rp in Fig. 24.37 that
will establish an in-phase relationship between vscope and
vi. Using schematics, obtain the waveform appearing on
the scope of Fig. 24.37 with a 20-V pulse input at a frequency
of 5 kHz.