Deck 17: Reactive Circuits and Power Factor

Question 1

Most electrical power used in industry is single-phase AC.

Answer 1

False

Question 2

What is the relationship between current and voltage in a purely resistive circuit?

A) The current lags the voltage by 90 $\degree$ .
B) The current leads the voltage by 90 $\degree$ .
C) The current and voltage are 180 $\degree$ out of phase with each other.
D) The current and voltage are in phase with each other.

Answer 2

The current and voltage are in phase with each other.

Question 3

An inductor with an inductive reactance of 48 $\Omega$ is connected in parallel with a 32 $\Omega$ resistor. What is the total impedance of this circuit?

A) 80 $\Omega$
B) 19.2 $\Omega$
C) 26.6 $\Omega$
D) 57.7 $\Omega$

Answer 3

26.6 $\Omega$

Question 4

What is the relationship of current and voltage in a purely capacitive circuit?

A) The current lags the voltage by 90 $\degree$ .
B) The current leads the voltage by 90 $\degree$ .
C) The current and voltage are 180 $\degree$ out of phase with each other.
D) The current and voltage are in phase with each other.

Question 5

A circuit contains resistance and inductance connected in series. The resistor has a true power of 560 W. The inductor has a reactive power of 430 VARs. What is the power factor of this circuit?

A) 79.3%
C) 60.9%
B) 76.8%
D) 83%

Question 6

What statement could be made concerning the phase angle in a circuit containing a small resistor and a large inductive reactance?

A) The phase angle will be 0 $\degree$ .
B) The phase angle will be greater than 0 $\degree$ but less than 45 $\degree$ .
C) The phase angle will be greater than 45 $\degree$ but less than 90 $\degree$ .
D) The phase angle will be 90 $\degree$ .

Question 7

What is the relationship of current and voltage in a purely inductive circuit?

A) The current lags the voltage by 90 $\degree$ .
B) The current leads the voltage by 90 $\degree$ .
C) The current and voltage are 180 $\degree$ out of phase with each other.
D) The current and voltage are in phase with each other.

Question 8

Two ___________________ in close proximity that are separated by some type of insulating material form a device called a capacitor

Question 9

The phase separation between the three single-phase AC sine waves in three-phase AC is ____.

A) 0°
C) 90°
B) 45°
D) 120°

Question 10

When dealing with capacitors, the insulating material is called a dielectric.

Question 11

What electrical quantity is used to measure inductance?

A) Farad
C) Hertz
B) Coulomb
D) Henry

Question 12

A 100 µF capacitor is connected to a 120 V, 60 Hz power line. What is the capacitive reactance of this circuit?

A) 0.04 $\Omega$
B) 43.7 $\Omega$
C) 26.54 $\Omega$
D) 94.2 $\Omega$

Question 13

When AC is applied across a capacitor, a ____ phase shift exists between the circuit current and capacitor voltage.

A) 45 $\degree$
B) 60 $\degree$
C) 63.2 $\degree$
D) 90 $\degree$

Question 14

The unit of measurement of capacitance is called a(n)____.

A) ohm ( $\Omega$ )
B) farad (F)
C) henry (H)
D) volt (V)

Question 15

Total opposition to current in a circuit that contains a combination of resistance and reactance is called ____.

A) resistance
C) VARs
B) impedance
D) reactance