Capacitive Reactance - Gibilisco MCQs in Electronics

MCQs in Capacitive Reactance from the book Teach Yourself Electricity and Electronics, 5th edition by Stan Gibilisco.

Multiple choice questions in Capacitive Reactance

This is the Multiple Choice Questions (MCQs) in Chapter 14: Capacitive Reactance 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. As the size of the plates in a capacitor increases, all other things being equal:

  • A. The value of XC increases negatively.
  • B. The value of XC decreases negatively.
  • C. The value of XC does not change.
  • D. You can’t say what happens to XC without more data.

2. If the dielectric material between the plates of a capacitor is changed, all other things being equal:

  • A. The value of XC increases negatively.
  • B. The value of XC decreases negatively.
  • C. The value of XC does not change.
  • D. You can’t say what happens to XC without more data.

3. As the frequency of a wave gets lower, all other things being equal, the value of XC for a capacitor:

  • A. Increases negatively.
  • B. Decreases negatively.
  • C. Does not change.
  • D. Depends on the current.

4. A capacitor has a value of 330 pF. What is its capacitive reactance at a frequency of 800 kHz?

  • A. -1.66 Ω.
  • B. -0.00166 Ω.
  • C. -603 Ω.
  • D. -603 K Ω.

5. A capacitor has a reactance of -4.50 Ω at 377 Hz. What is its capacitance?

  • A. 9.39 μF.
  • B. 93.9 μF.
  • C. 7.42 μF.
  • D. 74.2 μF.

6. A capacitor has a value of 47 μF. Its reactance is -47 Ω. What is the

frequency?

  • A. 72 Hz.
  • B. 7.2 MHz.
  • C. 0.000072 Hz.
  • D. 7.2 Hz.

7. A capacitor has XC = -8800 Ω at f = 830 kHz. What is C?

  • A. 2.18 μF.
  • B. 21.8 pF.
  • C. 0.00218 μF.
  • D. 2.18 pF.

8. A capacitor has C = 166 pF at f = 400 kHz. What is XC?

  • A. -2.4 K Ω.
  • B. -2.4 Ω.
  • C. -2.4 x 10-6 Ω.
  • D. -2.4 M Ω.

9. A capacitor has C = 4700 μF and XC = -33 Ω. What is f?

  • A. 1.0 Hz.
  • B. 10 Hz.
  • C. 1.0 kHz.
  • D. 10 kHz.

10. Each point in the RC plane:

  • A. Corresponds to a unique inductance.
  • B. Corresponds to a unique capacitance.
  • C. Corresponds to a unique combination of resistance and capacitance.
  • D. Corresponds to a unique combination of resistance and reactance.

11 If R increases in an RC circuit, but XC is always zero, then the vector in the RC plane will:

  • A. Rotate clockwise.
  • B. Rotate counterclockwise.
  • C. Always point straight towards the right.
  • D. Always point straight down.

12. If the resistance R increases in an RC circuit, but the capacitance and the frequency are nonzero and constant, then the vector in the RC plane will:

  • A. Get longer and rotate clockwise.
  • B. Get longer and rotate counterclockwise.
  • C. Get shorter and rotate clockwise.
  • D. Get shorter and rotate counterclockwise.

13. Each impedance R - jXC:

  • A. Represents a unique combination of resistance and capacitance.
  • B. Represents a unique combination of resistance and reactance.
  • C. Represents a unique combination of resistance and frequency.
  • D. All of the above.

14. In an RC circuit, as the ratio of capacitive reactance to resistance, -XC/R, gets closer to zero, the phase angle:

  • A. Gets closer to -90 degrees.
  • B. Gets closer to 0 degrees.
  • C. Stays the same.
  • D. Cannot be found.

15. In a purely resistive circuit, the phase angle is:

  • A. Increasing.
  • B. Decreasing.
  • C. 0 degrees.
  • D. -90 degrees.

16. If the ratio of XC/R is 1, the phase angle is:

  • A. 0 degrees.
  • B. -45 degrees.
  • C. -90 degrees.
  • D. Impossible to find; there’s not enough data given.

NOTE: For questions 17 - 18 see Fig.14-13.

Gibilisco MCQs image for CH14 Q17-18

17. In Fig. 14-13, the impedance shown is:

  • A. 8.02 + j323.
  • B. 323 + j8.02.
  • C. 8.02 - j323.
  • D. 323 - j8.02.

18. In Fig. 14-13, note that the R and XC scale divisions are not the same size. The phase angle is

  • A. 1.42 degrees.
  • B. About -60 degrees, from the looks of it.
  • C. -58.9 degrees.
  • D. -88.6 degrees.

19. An RC circuit consists of a 150-pF capacitor and a 330 Ω resistor in series. What is the phase angle at a frequency of 1.34 MHz?

  • A. –67.4 degrees.
  • B. –22.6 degrees.
  • C. –24.4 degrees.
  • D. –65.6 degrees.

20. An RC circuit has a capacitance of 0.015 μF. The resistance is 52 Ω. What is the phase angle at 90 kHz?

  • A. –24 degrees.
  • B. –0.017 degrees.
  • C. –66 degrees.
  • D. None of the above.

Complete List of Multiple Choice Questions from this Book

Check your work.


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