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  • Question
  • The coefficient of coupling between two coils is 0.45. The first coil has an inductance of 75 mH and the second coil has an inductance of 105 mH. What is the mutual inductance between the coils?


  • Options
  • A. 3.54 mH
  • B. 7.88 mH
  • C. 39.9 mH
  • D. 189.3 mH

  • Correct Answer
  • 39.9 mH 


  • Transformers problems


    Search Results


    • 1. Increasing the number of turns of wire on the secondary of a transformer will

    • Options
    • A. increase the secondary current
    • B. decrease the secondary current
    • C. have no effect on the secondary current
    • D. increase the primary current
    • Discuss
    • 2. A transformer has

    • Options
    • A. primary and secondary windings, both of which are considered inputs
    • B. primary and secondary windings, both of which are considered outputs
    • C. a primary winding used as an output and a secondary winding used as an input
    • D. a primary winding used as an input and a secondary winding used as an output
    • Discuss
    • 3. 

      What is the current through the load in the given circuit?


    • Options
    • A. 500 µA
    • B. 10 mA
    • C. 250 mA
    • D. 1.25 A
    • Discuss
    • 4. Which statement about a series RC circuit is true?

    • Options
    • A. The capacitor's voltage drop is in phase with the resistor's voltage drop.
    • B. The current leads the source voltage.
    • C. The current lags the source voltage.
    • D. The resistor voltage lags the current.
    • Discuss
    • 5. 

      What is the current through XC1 in the given circuit?


    • Options
    • A. 32.2 mA
    • B. 16 mA
    • C. 12 mA
    • D. 48 mA
    • Discuss
    • 6. What is the turns ratio of the transformer needed to match a 1 kΩ source resistance to a 160 Ω load?

    • Options
    • A. 2.5:1
    • B. 0.4:1
    • C. 6.25:1
    • D. 16:1
    • Discuss
    • 7. 

      If the load doubled in value in the given circuit, what reflected resistance would the source see?


    • Options
    • A. 80 Ω
    • B. 400 Ω
    • C. 2 kΩ
    • D. 10 kΩ
    • Discuss
    • 8. Mutual induction is dependent on

    • Options
    • A. winding ratios
    • B. output polarities
    • C. dc voltage levels
    • D. current changes
    • Discuss
    • 9. 

      What is the power dissipated in the primary of the transformer in the given circuit?


    • Options
    • A. 25 mW
    • B. 500 mW
    • C. 12.5 W
    • D. 62.5 W
    • Discuss
    • 10. A special transformer used to convert unbalanced signals to balanced signals is the

    • Options
    • A. balun
    • B. autotransformer
    • C. center-tapped transformer
    • D. step-across transformer
    • Discuss


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