Power and Resonance in AC circuits - Gibilisco MCQs in Electronics

MCQs in Power and Resonance in AC circuits from the book Teach Yourself Electricity and Electronics, 5th edition by Stan Gibilisco.

Multiple choice questions in Power and Resonance in AC circuits

This is the Multiple Choice Questions (MCQs) in Chapter 17: Power and Resonance in AC circuits from the book Teach Yourself Electricity and Electronics, 5th edition by Stan Gibilisco. If you are looking for a reviewer in Electronics Engineering this will definitely help you before taking the Board Exam.

Begin the Test

1. The power in a reactance is:

  • A. Radiated power.
  • B. True power.
  • C. Imaginary power.
  • D. Apparent power.

2. Which of the following is not an example of true power?

  • A. Power that heats a resistor.
  • B. Power radiated from an antenna.
  • C. Power in a capacitor.
  • D. Heat loss in a feed line.

3. The apparent power in a circuit is 100 watts, and the imaginary power is 40 watts. The true power is:

  • A. 92 watts.
  • B. 100 watts.
  • C. 140 watts.
  • D. Not determinable from this information.

4. Power factor is equal to:

  • A. Apparent power divided by true power.
  • B. Imaginary power divided by apparent power.
  • C. Imaginary power divided by true power.
  • D. True power divided by apparent power.

5. A circuit has a resistance of 300 W and an inductance of 13.5 μH in series at 10.0 MHz. What is the power factor?

  • A. 0.334.
  • B. 0.999.
  • C. 0.595.
  • D. It can’t be found from the data given.

6. A series circuit has Z = 88.4 Ω with R = 50.0 Ω What is PF?

  • A. 99.9 percent.
  • B. 56.6 percent.
  • C. 60.5 percent.
  • D. 29.5 percent.

7. A series circuit has R = 53.5 Ω and X = 75.5 Ω. What is PF?

  • A. 70.9 percent.
  • B. 81.6 percent.
  • C. 57.8 percent.
  • D. 63.2 percent.

8. Phase angle is equal to:

  • A. Arctan Z/R.
  • B. Arctan R/Z.
  • C. Arctan R/X.
  • D. Arctan X/R.

9. A wattmeter shows 220 watts of VA power in a circuit. There is a resistance of 50 Ω in series with a capacitive reactance of −20 Ω. What is the true power?

  • A. 237 watts.
  • B. 204 watts.
  • C. 88.0 watts.
  • D. 81.6 watts.

10. A wattmeter shows 57 watts of VA power in a circuit. The resistance is known to be 50 Ω, and the true power is known to be 40 watts. What is the absolute-value impedance?

  • A. 50 Ω
  • B. 57 Ω
  • C. 71 Ω
  • D. It can’t be calculated from this data.

11. Which of the following is the most important consideration in a transmission line?

  • A. The characteristic impedance.
  • B. The resistance.
  • C. Minimizing the loss.
  • D. The VA power.

12. Which of the following does not increase the loss in a transmission line?

  • A. Reducing the power output of the source.
  • B. Increasing the degree of mismatch between the line and the load.
  • C. Reducing the diameter of the line conductors.
  • D. Raising the frequency.

13. A problem that standing waves can cause is:

  • A. Feed line overheating.
  • B. Excessive power loss.
  • C. Inaccuracy in power measurement.
  • D. All of the above.

14. A coil and capacitor are in series. The inductance is 88 mH and the capacitance is 1000 pF. What is the resonant frequency?

  • A. 17 kHz.
  • B. 540 Hz.
  • C. 17 MHz.
  • D. 540 kHz.

15. A coil and capacitor are in parallel, with L = 10.0 μH and C = 10 pF. What is fo?

  • A. 15.9 kHz.
  • B. 5.04 MHz.
  • C. 15.9 MHz.
  • D. 50.4 MHz.

16. A series-resonant circuit is to be made for 14.1 MHz. A coil of 13.5 μH is available. What size capacitor is needed?

  • A. 0.945 μF.
  • B. 9.45 pF.
  • C. 94.5 pF.
  • D. 945 pF.

17. A parallel-resonant circuit is to be made for 21.3 MHz. A capacitor of 22.0 pF is available. What size coil is needed?

  • A. 2.54 mH.
  • B. 254 μH.
  • C. 25.4 μH.
  • D. 2.54 μH.

18. A 1/4-wave line section is made for 21.1 MHz, using cable with a velocity factor of 0.800. How many meters long is it?

  • A. 11.1 m.
  • B. 3.55 m.
  • C. 8.87 m.
  • D. 2.84 m.

19. The fourth harmonic of 800 kHz is:

  • A. 200 kHz.
  • B. 400 kHz.
  • C. 3.20 MHz.
  • D. 4.00 MHz.

20. How long is a 1/2-wave dipole for 3.60 MHz?

  • A. 130 feet.
  • B. 1680 feet.
  • C. 39.7 feet.
  • D. 515 feet.

Complete List of Multiple Choice Questions from this Book

Check your work.


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