Gibilisco - Capacitive Reactance

18 Questions | Total Attempts: 296

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Gibilisco - Capacitive Reactance

Questions and Answers
  • 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. 

      We cannot say what happens to XC without more data.

  • 2. 
    If the dielectric material between the plates of a capacitor is changed, all other things beingequal,
    • A. 

      The value of XC increases negatively.

    • B. 

      The value of XC decreases negatively.

    • C. 

      The value of XC does not change.

    • D. 

      We cannot 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 acapacitor
    • A. 

      Increases negatively.

    • B. 

      Decreases negatively.

    • C. 

      Does not change.

    • D. 

      Depends on the current.

  • 4. 
    What is the reactance of a 330-pF capacitor at 800 kHz?
    • A. 

      −1.66 Ω

    • B. 

      −0.00166 Ω

    • C. 

      −603 Ω

    • D. 

      −603 kΩ

  • 5. 
    Suppose 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. 
    Suppose a 47-µF capacitor has a reactance of −47 Ω. What is the frequency?
    • A. 

      72 Hz

    • B. 

      7.2 MHz

    • C. 

      0.000072 Hz

    • D. 

      7.2 Hz

  • 7. 
    Suppose 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. 
    Suppose a capacitor has C = 166 pF at f = 400 kHz. What is XC ?
    • A. 

      −2.4 kΩ

    • B. 

      −2.4 Ω

    • C. 

      −2.4 × 10−6 Ω

    • D. 

      −2.4 MΩ

  • 9. 
    Suppose 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, the vector in the RC plane will
    • A. 

      Rotate clockwise.

    • B. 

      Rotate counterclockwise.

    • C. 

      Always point straight toward the right.

    • D. 

      Always point straight down.

  • 12. 
    If the resistance R increases in an RC circuit, but the capacitance and the frequency arenonzero 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 complex impedance value 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 are true.

  • 14. 
    In an RC circuit, as the ratio XC /R approaches zero, the phase angle
    • A. 

      Approaches −90°.

    • B. 

      Approaches 0°.

    • C. 

      Stays the same.

    • D. 

      Cannot be found.

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

      Increasing.

    • B. 

      Decreasing.

    • C. 

      0°.

    • D. 

      −90°.

  • 16. 
    If XC /R =−1, then what is the phase angle?
    • A. 

    • B. 

      −45°

    • C. 

      −90°

    • D. 

      Impossible to find because there’s not enough data given

  • 17. 
    Suppose an RC circuit consists of a 150-pF capacitor and a 330-Ω resistor in series. What isthe phase angle at a frequency of 1.34 MHz?
    • A. 

      −67.4°

    • B. 

      −22.6°

    • C. 

      −24.4°

    • D. 

      −65.6°

  • 18. 
    Suppose an RC circuit has a capacitance of 0.015 µF. The resistance is 52 Ω. What is thephase angle at 90 kHz?
    • A. 

      −24°

    • B. 

      −0.017°

    • C. 

      −66°

    • D. 

      None of the above

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