Gibilisco - Alternating-current Basics

18 Questions | Total Attempts: 738

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Alternating Current Quizzes & Trivia

Questions and Answers
  • 1. 
    Which of the following can vary with ac, but never with dc?
    • A. 

      Power

    • B. 

      Voltage

    • C. 

      Frequency

    • D. 

      Amplitude

  • 2. 
    The length of time between a point in one cycle and the same point in the next cycle of an acwave is the
    • A. 

      Frequency.

    • B. 

      Magnitude.

    • C. 

      Period.

    • D. 

      Polarity.

  • 3. 
    On a spectrum analyzer, an ac signal having only one frequency component looks like
    • A. 

      A single pip.

    • B. 

      A sine wave.

    • C. 

      A square wave.

    • D. 

      A sawtooth wave.

  • 4. 
    The period of an ac wave, in seconds, is
    • A. 

      The same as the frequency in hertz.

    • B. 

      Not related to the frequency in any way.

    • C. 

      Equal to 1 divided by the frequency in hertz.

    • D. 

      Equal to the peak amplitude in volts divided by the frequency in hertz.

  • 5. 
    The sixth harmonic of an ac wave whose period is 1.000 millisecond (1.000 ms) has afrequency of
    • A. 

      0.006 Hz.

    • B. 

      167.0 Hz.

    • C. 

      7.000 kHz.

    • D. 

      6.000 kHz.

  • 6. 
    A degree of phase represents
    • A. 

      6.28 cycles.

    • B. 

      57.3 cycles.

    • C. 

      1⁄60 of a cycle.

    • D. 

      1⁄360 of a cycle.

  • 7. 
    Suppose that two ac waves have the same frequency but differ in phase by exactly 1⁄20 of a cycle. What is the phase difference between these two waves?
    • A. 

      18°

    • B. 

      20°

    • C. 

      36°

    • D. 

      5.73°

  • 8. 
    Suppose an ac signal has a frequency of 1770 Hz. What is its angular frequency?
    • A. 

      1770 rad/s

    • B. 

      11,120 rad/s

    • C. 

      282 rad/s

    • D. 

      Impossible to determine from the data given

  • 9. 
    A triangular wave exhibits
    • A. 

      An instantaneous rise and a defined decay.

    • B. 

      A defined rise and an instantaneous decay.

    • C. 

      A defined rise and a defined decay, and the two are equal.

    • D. 

      An instantaneous rise and an instantaneous decay.

  • 10. 
    Three-phase ac
    • A. 

      Has sawtooth waves that add together in phase.

    • B. 

      Consists of three sine waves in different phases.

    • C. 

      Is a sine wave with exactly three harmonics.

    • D. 

      Is of interest only to physicists.

  • 11. 
    If two perfect sine waves have the same frequency and the same amplitude, but are inopposite phase, the composite wave
    • A. 

      Has twice the amplitude of either input wave alone.

    • B. 

      Has half the amplitude of either input wave alone.

    • C. 

      Is complex, but has the same frequency as the originals.

    • D. 

      Has zero amplitude (that is, it does not exist), because the two input waves cancel each other out.

  • 12. 
    If two perfect sine waves have the same frequency and the same phase, the composite wave
    • A. 

      Is a sine wave with an amplitude equal to the difference between the amplitudes of the two input waves.

    • B. 

      Is a sine wave with an amplitude equal to the sum of the amplitudes of the two original waves.

    • C. 

      Is not a sine wave, but has the same frequency as the two input waves.

    • D. 

      Has zero amplitude (that is, it does not exist), because the two input waves cancel each other out.

  • 13. 
    In a 117-V rms utility circuit, the positive peak voltage is approximately
    • A. 

      +82.7 V.

    • B. 

      +165 V.

    • C. 

      +234 V.

    • D. 

      +331 V

  • 14. 
    In a 117-V rms utility circuit, the peak-to-peak voltage is approximately
    • A. 

      82.7 V.

    • B. 

      165 V.

    • C. 

      234 V.

    • D. 

      331 V.

  • 15. 
    In a perfect sine wave, the peak-to-peak amplitude is equal to
    • A. 

      Half the peak amplitude.

    • B. 

      The peak amplitude.

    • C. 

      1.414 times the peak amplitude.

    • D. 

      Twice the peak amplitude.

  • 16. 
    Which one of the following does not affect the power output available from a particular acgenerator?
    • 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

  • 17. 
    If a 175-V dc source were connected in series with the utility mains from a standard walloutlet, the result would be
    • A. 

      Smooth dc at a constant voltage.

    • B. 

      Pure ac with equal peak voltages.

    • C. 

      Ac with one peak voltage greater than the other.

    • D. 

      Fluctuating dc.

  • 18. 
    An advantage of ac over dc in utility applications is the fact that
    • 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 obtained from dc generators.

    • D. 

      Ac can be generated with less-dangerous by-products.

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