30
Figure 4B.
Bridge rectifier.
IN ANSWERING QUESTIONS 4-18 AND
4-19, REFER TO FIGURE 4-B.
4-18. When the voltage across the secondary of
the transformer has the polarity shown,
which of the diodes will conduct?
1. D1 and D3
2. D2 and D4
3. D1 and D2
4. D3 and D4
4-19. When the polarity reverses, which of the
diodes will conduct?
1. D3 and D1
2. D4 and D2
3. D2 and D1
4. D4 and D3
4-20. In filter circuits, inductors are used as
what type of impedance(s)?
1. Shunt impedance to oppose changes
in current
2. Shunt impedances to oppose changes
in voltage
3. Series impedances to oppose changes
in current
4. Series impedances to oppose changes
in voltage
4-21. To retain its charge, the capacitor in a
simple capacitor filter must have a long
charge time constant and a short
discharge time constant.
1. True
2. False
4-22. If you increase the value of a capacitor,
the XC will increase.
1. True
2. False
4-23. To obtain a steady dc output in a simple
capacitor circuit, the capacitor must
charge almost instantaneously to the
value of the applied voltage.
1. True
2. False
4-24. Which of the following factors, if any,
determines the rate of discharge of the
capacitor in a filter circuit?
1. The value of the load resistance
2. The amount of voltage
3. The type of capacitor
4. None of the above
4-25. A half-wave rectifier has an output
frequency of 60 hertz, a filter capacitor
value of 40 microfarads, and a load
resistance of 10 kilohms. What is the
value of XC?
1. 133.3 ohms
2. 26.5 ohms
3. 66.3 ohms
4. 40.0 ohms
