Power Supplies - Gibilisco MCQs in Electronics

MCQs in Power Supplies from the book Teach Yourself Electricity and Electronics, 5th edition by Stan Gibilisco.

Multiple choice questions in Power Supplies

This is the Multiple Choice Questions (MCQs) in Chapter 21: Power Supplies from the book Teach Yourself Electricity and Electronics, 5th edition by Stan Gibilisco. If you are looking for a reviewer in Electronics Engineering this will definitely help you before taking the Board Exam.

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1. The output of a rectifier is:

  • A. 60-Hz ac.
  • B. Smooth dc.
  • C. Pulsating dc.
  • D. 120-Hz ac.

2. Which of the following might not be needed in a power supply?

  • A. The transformer.
  • B. The filter.
  • C. The rectifier.
  • D. All of the above are generally needed.

3. Of the following appliances, which would need the biggest transformer?

  • A. A clock radio.
  • B. A TV broadcast transmitter.
  • C. A shortwave radio receiver.
  • D. A home TV set.

4. An advantage of full-wave bridge rectification is:

  • A. It uses the whole transformer secondary for the entire ac input cycle.
  • B. It costs less than other rectifier types.
  • C. It cuts off half of the ac wave cycle.
  • D. It never needs a regulator.

5. In. a supply designed to provide high power at low voltage, the best rectifier design would probably be:

  • A. Half-wave.
  • B. Full-wave, center-tap.
  • C. Bridge.
  • D. Voltage multiplier.

6. The part of a power supply immediately preceding the regulator is:

  • A. The transformer.
  • B. The rectifier.
  • C. The filter.
  • D. The ac input.

7. If a half-wave rectifier is used with 117-V rms ac (house mains), the average dc output voltage is about:

  • A. 52.7 V.
  • B. 105 V.
  • C. 117 V.
  • D. 328 V.

8. If a full-wave bridge circuit is used with a transformer whose secondary provides 50 V rms, the PIV across the diodes is about:

  • A. 50 V.
  • B. 70 V.
  • C. 100 V.
  • D. 140 V.

9. The principal disadvantage of a voltage multiplier is:

  • A. Excessive current.
  • B. Excessive voltage.
  • C. Insufficient rectification.
  • D. Poor regulation.

10. A transformer secondary provides 10 V rms to a voltage-doubler circuit. The dc output voltage is about:

  • A. 14 V.
  • B. 20 V.
  • C. 28 V.
  • D. 36 V.

11. The ripple frequency from a full-wave rectifier is:

  • A. Twice that from a half-wave circuit.
  • B. The same as that from a half-wave circuit.
  • C. Half that from a half-wave circuit.
  • D. One-fourth that from a half-wave circuit.

12. Which of the following would make the best filter for a power supply?

  • A. A capacitor in series.
  • B. A choke in series.
  • C. A capacitor in series and a choke in parallel.
  • D. A capacitor in parallel and a choke in series.

13. If you needed exceptionally good ripple filtering for a power supply, the best approach would be to:

  • A. Connect several capacitors in parallel.
  • B. Use a choke-input filter.
  • C. Connect several chokes in series.
  • D. Use two capacitor/choke sections one after the other.

14. Voltage regulation can be accomplished by a Zener diode connected in:

  • A. Parallel with the filter output, forward-biased.
  • B. Parallel with the filter output, reverse-biased.
  • C. Series with the filter output, forward-biased.
  • D. Series with the filter output, reverse-biased.

15. A current surge takes place when a power supply is first turned on because:

  • A. The transformer core is suddenly magnetized.
  • B. The diodes suddenly start to conduct.
  • C. The filter capacitor(s) must be initially charged.
  • D. Arcing takes place in the power switch.

16. Transient suppression minimizes the chance of:

  • A. Diode failure.
  • B. Transformer failure.
  • C. Filter capacitor failure.
  • D. Poor voltage regulation.

17. If a fuse blows, and it is replaced with one having a lower current rating, there’s a good chance that:

  • A. The power supply will be severely damaged.
  • B. The diodes will not rectify.
  • C. The fuse will blow out right away.
  • D. Transient suppressors won’t work.

18. A fuse with nothing but a straight wire inside is probably:

  • A. A slow-blow type.
  • B. A quick-break type.
  • C. Of a low current rating.
  • D. Of a high current rating.

19. Bleeder resistors are:

  • A. Connected in parallel with filter capacitors.
  • B. Of low ohmic value.
  • C. Effective for transient suppression.
  • D. Effective for surge suppression.

20. To service a power supply with which you are not completely familiar, you should:

  • A. Install bleeder resistors.
  • B. Use proper fusing.
  • C. Leave it alone and have a professional work on it.
  • D. Use a voltage regulator.

Complete List of Multiple Choice Questions from this Book

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