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Home Electrical Engineering RL Circuits Comments

  • Question
  • If the frequency is halved and the resistance is doubled, the impedance of a series RL circuit


  • Options
  • A. doubles
  • B. halves
  • C. remains constant
  • D. cannot be determined without values

  • Correct Answer
  • cannot be determined without values 


  • RL Circuits problems


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    • 1. A 140 Ω resistor is in parallel with an inductor having 60 Ω inductive reactance. Both components are across a 12 V ac source. The magnitude of the total impedance is

    • Options
    • A. 5.51 Ω
    • B. 55.15 Ω
    • C. 90 Ω
    • D. 200 Ω
    • Discuss
    • 2. Which of the following power factors results in less energy loss in an RL circuit?

    • Options
    • A. 1
    • B. 0.8
    • C. 0.4
    • D. 0.2
    • Discuss
    • 3. If a load is purely inductive and the reactive power is 12 VAR, the apparent power is

    • Options
    • A. 0 VA
    • B. 12 VA
    • C. 6 VA
    • D. 24 VA
    • Discuss
    • 4. A 1.5 kΩ resistor and a coil with a 2.2 kΩ inductive reactance are in series across an 18 V ac source. The power factor is

    • Options
    • A. 564
    • B. 0.564
    • C. 6.76
    • D. 55.7
    • Discuss
    • 5. To increase the current in a series RL circuit, the frequency

    • Options
    • A. should be increased
    • B. should be decreased
    • C. should be constant
    • D. cannot be determined without values
    • Discuss
    • 6. The voltages in Problem 5 are measured at a certain frequency. To make the resistor voltage less than the inductor voltage, the frequency is

    • Options
    • A. increased
    • B. decreased
    • C. doubled
    • D. not a factor
    • Discuss
    • 7. A 12 kΩ resistor is in series with a 90 mH coil across an 8 kHz ac source. Current flow in the circuit, expressed in polar form, is I = 0.3∠0° mA. The source voltage, expressed in polar form, is

    • Options
    • A. 3.84∠20.6° V
    • B. 12.8∠20.6° V
    • C. 0.3∠20.6° V
    • D. 13.84∠69.4° V
    • Discuss
    • 8. Referring to Problem 18, the circuit impedance is

    • Options
    • A. 458 ∠?76° Ω
    • B. 4.58 ∠?76° Ω
    • C. 458∠76° Ω
    • D. 4.58∠76° Ω
    • Discuss
    • 9. When the frequency of the voltage applied to a series RL circuit is decreased, the impedance

    • Options
    • A. decreases
    • B. increases
    • C. does not change
    • D. cannot be determined without values
    • Discuss
    • 10. A 47 Ω resistor is in series with an inductive reactance of 120 Ω across an ac source. The impedance, expressed in polar form, is

    • Options
    • A. 47∠68.6° Ω
    • B. 120∠68.6° Ω
    • C. 129∠31.4° Ω
    • D. 129∠68.6° Ω
    • Discuss


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