Gibilisco - Electrical Units

20 ntrebri | Total Attempts: 1660

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Gibilisco - Electrical Units

Questions and Answers
  • 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 1 V
    • 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 utility power plant.

    • D. 

      A small radio set.

  • 5. 
    A piece of wire has a conductance of 20 S. 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 Ω. Its conductance is
    • A. 

      3.33 mS.

    • B. 

      33.3 mS.

    • C. 

      333 µS.

    • D. 

      0.333 S.

  • 7. 
    A span of wire 1 km long has a conductance of 0.6 S. What is the conductance of a span ofthis same wire that is 3 km long?
    • A. 

      1.8 S

    • B. 

      0.6 S

    • C. 

      0.2 S

    • D. 

      More information is necessary to determine this.

  • 8. 
    Approximately how much current can a 2-kW generator reliably deliver 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. Approximately how much power does this represent?
    • A. 

      1.76 kW

    • B. 

      1760 kW

    • C. 

      7.8 kW

    • D. 

      0.0078 kW

  • 10. 
    You are told that an air conditioner has cooled a room by 500 Btu over a certain period oftime. What is this amount of energy in kWh?
    • A. 

      147 kWh

    • B. 

      14.7 kWh

    • C. 

      1.47 kWh

    • D. 

      0.147 kWh

  • 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 United States 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 cut off.

    • C. 

      The whole ac wave is inverted.

    • D. 

      The effective voltage is half the peak voltage.

  • 14. 
    In the output of a half-wave rectifier,
    • A. 

      Half of the ac input wave is inverted.

    • B. 

      The effective voltage is less than that of the ac input wave.

    • C. 

      The effective voltage is the same as that of the ac input wave.

    • D. 

      The effective voltage is more than that of the ac input wave.

  • 15. 
    In the output of a full-wave rectifier,
    • A. 

      Half of the ac input wave is inverted.

    • B. 

      The effective voltage is less than that of the ac input wave.

    • C. 

      The effective voltage is the same as that of the ac input wave.

    • D. 

      The effective voltage is more than that of the ac input 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 the following units 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 is
    • A. 

      37,500 At.

    • B. 

      375 At.

    • C. 

      37.5 At.

    • D. 

      3.75 At.

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