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  • Question
  • What is the number of turns required in the secondary winding for a transformer when 120 volts is applied to a 2400-turn primary to produce 7.5 Vac at the secondary?


  • Options
  • A. 75 turns
  • B. 150 turns
  • C. 900 turns
  • D. 1920 turns

  • Correct Answer
  • 150 turns 


  • Inductors problems


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    • 1. The polarity of induced voltage while a field is collapsing is:

    • Options
    • A. independent of the force creating it
    • B. opposite to the force creating it
    • C. identical to the force creating the field
    • D. present only if the force is stationary
    • Discuss
    • 2. On a schematic, dashed lines between two vertical coils usually mean the transformer has:

    • Options
    • A. an air core
    • B. an iron core
    • C. a nonmetallic core
    • D. a ferrite core
    • Discuss
    • 3. What is the phase angle of a 24 Vac parallel RL circuit when R = 45 ohms and XL = 1100 ohms?

    • Options
    • A. 0.001 degrees
    • B. 2.300 degrees
    • C. 87.600 degrees
    • D. 89.900 degrees
    • Discuss
    • 4. When current in an inductor starts to change, it cannot react instantly due to:

    • Options
    • A. fixed coil resistance
    • B. eddy current generation
    • C. applied emf of the circuit
    • D. the counter emf of the coil
    • Discuss
    • 5. Which transformer turns ratio is needed to match two 16-ohm parallel devices to an output of 22.2 ohms?

    • Options
    • A. 1.38:1
    • B. 1.67:1
    • C. 0.72:1
    • D. 0.60:1
    • Discuss
    • 6. A loaded transformer will achieve mutual induction when:

    • Options
    • A. secondary current increase causes a primary current decrease
    • B. primary current is increased by an increase in secondary current
    • C. primary current is decreased by an increase in secondary current
    • D. secondary current decrease causes a primary current increase
    • Discuss
    • 7. When used as a filter, an inductor is

    • Options
    • A. placed in series with the load and aids any current changes
    • B. placed in parallel with the load and aids any current changes
    • C. placed in parallel with the load and opposes any current changes
    • D. placed in series with the load and opposes any current changes
    • Discuss
    • 8. What term is used to describe the action of magnetic flux from one circuit that cuts across the conductors of another circuit?

    • Options
    • A. self-inductance
    • B. rectification
    • C. mutual inductance
    • D. magnetism
    • Discuss
    • 9. Find VR and VL.


    • Options
    • A. VR = 41.6 V, VL = 78.4 V
    • B. VR = 48 V, VL = 110 V
    • C. VR = 56 V, VL = 106 V
    • D. VR = 60 V, VL = 60 V
    • Discuss
    • 10. Faraday's law states that the:

    • Options
    • A. direction of the induced voltage produces an opposition
    • B. direction of an induced current produces an aiding effect
    • C. emf depends on the rate of cutting flux
    • D. emf is related to the direction of the current
    • Discuss


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