Chapter 9 : Alternating Current Basics (Gibilisco)

20 Questions | Total Attempts: 289

SettingsSettingsSettings
Please wait...
Chapter 9 : Alternating Current Basics (Gibilisco)

.


Questions and Answers
  • 1. 
    Which of the following can vary with ac, but not with dc?
    • A. 

      Power

    • B. 

      Voltage

    • C. 

      Frequency

    • D. 

      Magnitude

  • 2. 
    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

  • 3. 
    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

  • 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 amplitude divided by the frequency

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

      0.006Hz

    • B. 

      167 Hz

    • C. 

      7kHz

    • D. 

      6kHz

  • 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 triangular frequency:
    • A. 

      Has a fast rise time and slow decay time

    • B. 

      Has a slow rise time and fast decay time

    • C. 

      Has equal rise and decay rates

    • D. 

      Rises and falls abruply

  • 9. 
    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

  • 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 of the amplitude of either wave alone

    • C. 

      A xomplex 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 117V utility circuit, the peak voltage is:
    • A. 

      82.7V

    • B. 

      165V

    • C. 

      234V

    • D. 

      331V

  • 14. 
    In a 117V utility circuits, the peak-to-peak voltage is:
    • A. 

      82.7V

    • B. 

      165V

    • C. 

      234V

    • D. 

      331V

  • 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

  • 16. 
    If a 45Vdc battery is connected in series with the 117V utility mains as shown in Fig. 9-15, the peak voltage will be:
    • A. 

      + 210V and - 120V

    • B. 

      + 162V and - 72V

    • C. 

      + 396V and - 286V

    • D. 

      Both equal to 117V

  • 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 the fact that:
    • A. 

      Ac is easier to transform one voltage to another.

    • B. 

      Ac is transmitted with loss in wires

    • C. 

      Ac can be easily gotten from dc generators

    • D. 

      Ac can be generated with less dangerous by products