Regulated D.C. Power Supply

21. If the input a.c. voltage to regulated or ordinary power supply increases by 5% what will be the approximate change in d.c. output voltage?

1. 10%
2. 20%
3. 15%
4. 5%

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22. If the load current drawn by unregulated power supply increases, the d.c. output voltage __________

1. Increases
2. Decreases
3. Stays the same
4. None of the above

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23. If the load resistance decreases in a Zener regulator, then Zener current __________

1. Decreases
2. Stays the same
3. Increases
4. None of the above

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24. In a 15 V Zener diode , the breakdown mechanism will occur by __________

1. Avalanche mechanism
2. Zener mechanism
3. Both Zener and avalanche mechanism
4. None of the above

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25. In a loaded Zener regulator, which is the largest Zener current?

1. Series current
2. Zener current
3. Load current
4. None of the above

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26. In a regulated power supply, two similar 15 V zeners are connected in series. The input voltage is 45 V d.c. If each Zener has a maximum current rating of 300 mA, what should be the value of the series resistance?

1. 10 O
2. 50 O
3. 25 O
4. 40 O

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27. In a Zener voltage regulator, the changes in load current produce changes in __________

1. Zener current
2. Zener voltage
3. Zener voltage as well as Zener current
4. None of the above

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28. In an unregulated power supply, if input a.c. voltage increases, the output voltage __________

1. Increases
2. Decreases
3. Remains the same
4. None of the above

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29. In an unregulated power supply, if load current increases, the output voltage __________

1. Remains the same
2. Decreases
3. Increases
4. None of the above

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30. The current in a Zener diode is limited by …__________

1. External resistance
2. Power dissipation
3. Both (1) and (2)
4. None of the above

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