 Alternating Current Basics – Gibilisco MCQs in Electronics

(Last Updated On: December 8, 2017) This is the Multiple Choice Questions (MCQs) in Chapter 9: Alternating Current Basics 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.

Start Practice Exam Test Questions

1. Which of the following can vary with ac, but not with dc?

• A. Power.
• B. Voltage.
• C. Frequency.
• D. Magnitude.

2. The length of time between a point in one cycle and the same point in the next cycle of an ac wave is the:

• A. Frequency.
• B. Magnitude.
• C. Period.
• D. Polarity.

3. On a spectrum analyzer, a pure ac signal, having just one frequency component, would look like:

• A. A single pip.
• B. A perfect sine wave.
• C. A square wave.
• D. A sawtooth wave.

4. The period of an ac wave is:

• A. The same as the frequency.
• B. Not related to the frequency.
• C. Equal to 1 divided by the frequency.
• D. Equal to the amplitude divided by the frequency.

5. The sixth harmonic of an ac wave whose period is 0.001 second has a frequency of

• A. 0.006 Hz.
• B. 167 Hz.
• C. 7 kHz.
• D. 6 kHz.

6. A degree of phase represents:

• A. 6.28 cycles.
• B. 57.3 cycles.
• C. 1/6.28 cycle.
• D. 1/360 cycle.

7. Two waves have the same frequency but differ in phase by 1/20 cycle. The phase difference in degrees is:

• A. 18.
• B. 20.
• C. 36.
• D. 5.73.

8. A signal has a frequency of 1770 Hz. The angular frequency is:

• A. 1770 radians per second.
• B. 11,120 radians per second.
• C. 282 radians per second.
• D. Impossible to determine from the data given.

9. A triangular wave:

• A. Has a fast rise time and a slow decay time.
• B. Has a slow rise time and a fast decay time.
• C. Has equal rise and decay rates.
• D. Rises and falls abruptly.

10. Three-phase ac:

• A. Has waves that add up to three times the originals.
• B. Has three waves, all of the same magnitude.
• C. Is what you get at a common wall outlet.
• D. Is of interest only to physicists.

11. If two waves have the same frequency and the same amplitude, but opposite phase, the composite wave is:

• A. Twice the amplitude of either wave alone.
• B. Half the amplitude of either wave alone.
• C. A complex waveform, but with the same frequency as the originals.
• D. Zero.

12. If two waves have the same frequency and the same phase, the composite wave:

• A. Has a magnitude equal to the difference between the two originals.
• B. Has a magnitude equal to the sum of the two originals.
• C. Is complex, with the same frequency as the originals.
• D. Is zero.

13. In a 117-V utility circuit, the peak voltage is:

• A. 82.7 V.
• B. 165 V.
• C. 234 V.
• D. 331 V.

14. In a 117-V utility circuit, the pk-pk voltage is:

• A. 82.7 V.
• B. 165 V.
• C. 234 V.
• D. 331 V.

15. In a perfect sine wave, the pk-pk value is:

• A. Half the peak value.
• B. The same as the peak value.
• C. 1.414 times the peak value.
• D. Twice the peak value.

NOTE: For questions 16 see Fig. 9-15. 16. If a 45-Vdc battery is connected in series with the 117-V utility mains as shown in Fig. 9-15, the peak voltages will be:

• A. + 210 V and – 120 V.
• B. + 162 V and – 72 V.
• C. + 396 V and – 286 V.
• D. Both equal to 117 V.

17. In the situation of question 16, the pk-pk voltage will be:

• A. 117 V.
• B. 210 V.
• C. 331 V.
• D. 396 V.

18. Which one of the following does not affect the power output available from a particular ac generator?

• A. The strength of the magnet.
• B. The number of turns in the coil.
• C. The type of natural energy source used.
• D. The speed of rotation of the coil or magnet.

19. If a 175-V dc source were connected in series with the utility mains from a standard wall outlet, the result would be:

• A. Smooth dc.
• B. Smooth ac.
• C. Ac with one peak greater than the other.
• D. Pulsating dc.

20. An advantage of ac over dc in utility applications is:

• A. Ac is easier to transform from one voltage to another.
• B. Ac is transmitted with lower loss in wires.
• C. Ac can be easily gotten from dc generators.
• D. Ac can be generated with less dangerous by-products.