Question 1

Two capacitors, a 20 μ F and a 30 μ F, are connected in parallel to a 400 Hz source. What is the total capacitive reactance?

Accepted Answer

A)  7.96 Ω 
B)  33.16 Ω 
C)  42.04 Ω 
D)  53.05 Ω 
A)  7.96 Ω 
B)  33.16 Ω 
C)  42.04 Ω 
D)  53.05 Ω A

Question 2

A 1 μ F capacitor has 2,652 Ω of reactance at 60 Hz. What is the reactance value at 400 Hz?

Accepted Answer

A)  397.88 Ω 
B)  568.72 Ω 
C)  639.79 Ω 
D)  768.33 Ω 
A)  397.88 Ω 
B)  568.72 Ω 
C)  639.79 Ω 
D)  768.33 Ω A

Question 3

Countervoltage presented by a capacitor is called _____.

Accepted Answer

A)  capacitance 
B)  inductance 
C)  capacitive reactance 
D)  inductive reactance 
A)  capacitance 
B)  inductance 
C)  capacitive reactance 
D)  inductive reactance C

Question 4

A capacitor is connected to a 240 V supply. An ammeter indicates 3 A. What is the capacitive reactance of the capacitor?

Accepted Answer

A)  23 Ω 
B)  30 Ω 
C)  71 Ω 
D)  80 Ω 
A)  23 Ω 
B)  30 Ω 
C)  71 Ω 
D)  80 Ω

Question 5

What is the reactance of a 25 μ F capacitor when the applied frequency is 400 Hz?

Accepted Answer

A)  10.61 Ω 
B)  11.59 Ω 
C)  15.92 Ω 
D)  16.12 Ω 
A)  10.61 Ω 
B)  11.59 Ω 
C)  15.92 Ω 
D)  16.12 Ω

Question 6

A 35 μ F capacitor is connected to a 60-Hz, 120 V supply. What is the XC of the capacitor?

Accepted Answer

A)  75.79 Ω 
B)  80.33 Ω 
C)  83.2 Ω 
D)  93.43 Ω 
A)  75.79 Ω 
B)  80.33 Ω 
C)  83.2 Ω 
D)  93.43 Ω

Question 7

Three capacitors, a 12 μ F, a 20 μ F, and a 30 μ F, are connected in parallel to a 60 Hz source. What is the total XC?

Accepted Answer

A)  6.42 Ω 
B)  42.78 Ω 
C)  442.09 Ω 
D)  566.32 Ω 
A)  6.42 Ω 
B)  42.78 Ω 
C)  442.09 Ω 
D)  566.32 Ω

Question 8

The quality of a capacitor is found by Q = _____.

Accepted Answer

A)  XC/R 
B)  R/XC 
C)  PF 
D)  W/VARs 
A)  XC/R 
B)  R/XC 
C)  PF 
D)  W/VARs

Question 9

In a pure capacitive circuit, the current _____ the applied voltage by _____.

Accepted Answer

A)  leads; 180 ° 
B)  lags; 180 ° 
C)  leads; 90 ° 
D)  lags; 90 ° 
A)  leads; 180 ° 
B)  lags; 180 ° 
C)  leads; 90 ° 
D)  lags; 90 °

Question 10

Three capacitors, a 12 μ F, a 20 μ F, and a 30 μ F, are connected in parallel to a 400 Hz source. What is the total XC?

Accepted Answer

A)  6.42 Ω 
B)  42.78 Ω 
C)  44.09 Ω 
D)  56.32 Ω 
A)  6.42 Ω 
B)  42.78 Ω 
C)  44.09 Ω 
D)  56.32 Ω

Question 11

Two capacitors, a 20 μ F and a 30 μ F, are connected in parallel to a 60 Hz source. What is the total capacitive reactance?

Accepted Answer

A)  7.96 Ω 
B)  23.16 Ω 
C)  42.04 Ω 
D)  53.05 Ω 
A)  7.96 Ω 
B)  23.16 Ω 
C)  42.04 Ω 
D)  53.05 Ω

Question 12

When a capacitor is connected to a(n) _____ circuit, current appears to flow through the capacitor.

Accepted Answer

A)  DC 
B)  AC 
A)  DC 
B)  AC

Question 13

Three capacitors, a 12 ? F, a 20 ? F, and a 30 ? F, are connected in series to a 400 Hz source. What is the total XC ?

Accepted Answer

A)  36.42 ? 
B)  42.78 ? 
C)  52.09 ? 
D)  66.32 ? 
A)  36.42 ? 
B)  42.78 ? 
C)  52.09 ? 
D)  66.32 ?

Question 14

​When the voltage and current have _____ polarities in a pure capacitive circuit, the capacitor is discharging and the energy is returned to the circuit.

Accepted Answer

A)  ​the same 
B)  ​opposite 
A)  ​the same 
B)  ​opposite

Question 15

Two capacitors, a 20 μ F and a 30 μ F, are connected in series to a 400 Hz source. What is the total capacitive reactance?

Accepted Answer

A)  7.96 Ω 
B)  33.16 Ω 
C)  42.04 Ω 
D)  53.05 Ω 
A)  7.96 Ω 
B)  33.16 Ω 
C)  42.04 Ω 
D)  53.05 Ω

Question 16

The power in a capacitor is reactive power. What is the unit for reactive power?

Accepted Answer

A)  W 
B)  VA 
C)  P 
D)  VAR 
A)  W 
B)  VA 
C)  P 
D)  VAR

Question 17

What is the symbol for capacitive reactance?

Accepted Answer

A)  C 
B)  XC 
C)  L 
D)  XL 
A)  C 
B)  XC 
C)  L 
D)  XL

Question 18

In a circuit containing a capacitor, the impressed voltage is _____ with the applied voltage.

Accepted Answer

A)  180 ° out of phase 
B)  90 ° out of phase 
C)  in phase 
D)  270 ° out of phase 
A)  180 ° out of phase 
B)  90 ° out of phase 
C)  in phase 
D)  270 ° out of phase

Question 19

The capacitive reactance of a capacitor is _____ proportional to frequency.

Accepted Answer

A)  directly 
B)  inversely 
A)  directly 
B)  inversely

Question 20

Two capacitors, a 20 μ F and a 30 μ F, are connected in series to a 60 Hz source. What is the total capacitive reactance?

Accepted Answer

A)  117.96 Ω 
B)  221.04 Ω 
C)  253.05 Ω 
D)  333.16 Ω 
A)  117.96 Ω 
B)  221.04 Ω 
C)  253.05 Ω 
D)  333.16 Ω

Exam 21: Capacitance in Ac Circuits

Two capacitors, a 20 μ F and a 30 μ F, are connected in parallel to a 400 Hz source. What is the total capacitive reactance?

A 1 μ F capacitor has 2,652 Ω of reactance at 60 Hz. What is the reactance value at 400 Hz?

Countervoltage presented by a capacitor is called _____.

A capacitor is connected to a 240 V supply. An ammeter indicates 3 A. What is the capacitive reactance of the capacitor?

What is the reactance of a 25 μ F capacitor when the applied frequency is 400 Hz?

A 35 μ F capacitor is connected to a 60-Hz, 120 V supply. What is the XC of the capacitor?

Three capacitors, a 12 μ F, a 20 μ F, and a 30 μ F, are connected in parallel to a 60 Hz source. What is the total XC?

The quality of a capacitor is found by Q = _____.

In a pure capacitive circuit, the current _____ the applied voltage by _____.

Three capacitors, a 12 μ F, a 20 μ F, and a 30 μ F, are connected in parallel to a 400 Hz source. What is the total XC?

Two capacitors, a 20 μ F and a 30 μ F, are connected in parallel to a 60 Hz source. What is the total capacitive reactance?

When a capacitor is connected to a(n) _____ circuit, current appears to flow through the capacitor.

Three capacitors, a 12 ? F, a 20 ? F, and a 30 ? F, are connected in series to a 400 Hz source. What is the total XC ?

​When the voltage and current have _____ polarities in a pure capacitive circuit, the capacitor is discharging and the energy is returned to the circuit.

Two capacitors, a 20 μ F and a 30 μ F, are connected in series to a 400 Hz source. What is the total capacitive reactance?

The power in a capacitor is reactive power. What is the unit for reactive power?

What is the symbol for capacitive reactance?

In a circuit containing a capacitor, the impressed voltage is _____ with the applied voltage.

The capacitive reactance of a capacitor is _____ proportional to frequency.

Two capacitors, a 20 μ F and a 30 μ F, are connected in series to a 60 Hz source. What is the total capacitive reactance?

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A 35 μ F capacitor is connected to a 60-Hz, 120 V supply. What is the X_C of the capacitor?

Three capacitors, a 12 μ F, a 20 μ F, and a 30 μ F, are connected in parallel to a 60 Hz source. What is the total X_C?

In a pure capacitive circuit, the current _ the applied voltage by _.

Three capacitors, a 12 μ F, a 20 μ F, and a 30 μ F, are connected in parallel to a 400 Hz source. What is the total X_C?

When the voltage and current have _____ polarities in a pure capacitive circuit, the capacitor is discharging and the energy is returned to the circuit.