# Gibilisco - Capacitive Reactance

18 Questions | Total Attempts: 296  Settings  • 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 Back to top