This is the Multiple Choice Questions (MCQs) in Chapter 2: Electrical Units 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.
Topic Outline for the Chapter 2 MCQs
- The Volt
- The Ampere
- Resistance and the Ohm
- Conductance and the Siemens
- Power and the Watt
- A Word about Notation/li>
- Energy and the Watt-Hour
- Alternating Current and the Hertz
- Safety Considerations in Electrical Work
- Magnetism
- Magnetic Units
- Other Energy Units
start Practice Exam Test Questions
1. A positive electric pole:
- A. Has a deficiency of electrons.
- B. Has fewer electrons than the negative pole.
- C. Has an excess of electrons.
- D. Has more electrons than the negative pole
2. An EMF of one volt:
- A. Cannot drive much current through a circuit.
- B. Represents a low resistance.
- C. Can sometimes produce a large current.
- D. Drops to zero in a short time.
3. A potentially lethal electric current is on the order of:
- A. 0.01 mA.
- B. 0.1 mA.
- C. 1 mA.
- D. 0.1 A.
4. A current of 25 A is most likely drawn by:
- A. A flashlight bulb.
- B. A typical household.
- C. A power plant.
- D. A clock radio.
5. A piece of wire has a conductance of 20 siemens. Its resistance is:
- A. 20 Ω.
- B. 0.5 Ω.
- C. 0.05 Ω.
- D. 0.02 Ω.
6. A resistor has a value of 300 ohms. Its conductance is:
- A. 3.33 millisiemens.
- B. 33.3 millisiemens.
- C. 333 microsiemens.
- D. 0.333 siemens.
7. A mile of wire has a conductance of 0.6 siemens. Then three miles of the same wire has a conductance of:
- A. 1.8 siemens.
- B. 1.8 Ω.
- C. 0.2 siemens.
- D. Not enough information has been given to answer this.
8. A 2-kW generator will deliver approximately how much current, reliably, at 117 V?
- A. 17 mA.
- B. 234 mA.
- C. 17 A.
- D. 234 A.
9. A circuit breaker is rated for 15 A at 117 V. This represents approximately how many kilowatts?
- A. 1.76.
- B. 1760.
- C. 7.8.
- D. 0.0078.
10. You are told that a certain air conditioner is rated at 500 Btu. What is this in kWh?
- A. 147.
- B. 14.7.
- C. 1.47.
- D. 0.147.
11. Of the following energy units, the one most often used to define electrical energy is:
- A. The Btu.
- B. The erg.
- C. The foot pound.
- D. The kilowatt hour.
12. The frequency of common household ac in the U.S. is:
- A. 60 Hz.
- B. 120 Hz.
- C. 50 Hz.
- D. 100 Hz.
13. Half-wave rectification means that:
- A. Half of the ac wave is inverted.
- B. Half of the ac wave is chopped off.
- C. The whole wave is inverted.
- D. The effective value is half the peak value.
14. In the output of a half-wave rectifier:
- A. Half of the wave is inverted.
- B. The effective value is less than that of the original ac wave.
- C. The effective value is the same as that of the original ac wave.
- D. The effective value is more than that of the original ac wave.
15. In the output of a full-wave rectifier:
- A. The whole wave is inverted.
- B. The effective value is less than that of the original ac wave.
- C. The effective value is the same as that of the original ac wave.
- D. The effective value is more than that of the original ac wave.
16. A low voltage, such as 12 V:
- A. Is never dangerous.
- B. Is always dangerous.
- C. Is dangerous if it is ac, but not if it is dc.
- D. Can be dangerous under certain conditions.
17. Which of these can represent magnetomotive force?
- A. The volt-turn.
- B. The ampere-turn.
- C. The gauss.
- D. The gauss-turn.
18. Which of the following units can represent magnetic flux density?
- A. The volt-turn.
- B. The ampere-turn.
- C. The gauss.
- D. The gauss-turn.
19. A ferromagnetic material:
- A. Concentrates magnetic flux lines within itself.
- B. Increases the total magnetomotive force around a current-carrying wire.
- C. Causes an increase in the current in a wire.
- D. Increases the number of ampere-turns in a wire.
20. A coil has 500 turns and carries 75 mA of current. The magnetomotive force will be:
- A. 37,500 At.
- B. 375 At.
- C. 37.5 At.
- D. 3.75 At.
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