Question 1

A transformer is used to step up the voltage to a power line. If the stepped-up voltage is 10 times the original value, by how much will the power loss in the line decrease?

Accepted Answer

A)  more than 95% 
B)  between 10% and 20% 
C)  between 20% and 95% 
D)  There will be no change since the power into a transformer equals the power out.

Question 2

A resistor, inductor, and capacitor are connected in series, each with effective (rms) voltage of 65 V, 150 V, and 80 V, respectively. What is the value of the effective (rms) voltage of the applied source in the circuit?

Accepted Answer

A)  295 V 
B)  48 V 
C)  96 V 
D)  88 V

Question 3

The frequency in an AC series circuit is halved. By what factor does this change the capacitive reactance?

Accepted Answer

A)  1/2 
B)  4 
C)  1/4 
D)  2

Question 4

In an AC series circuit, the current in a pure resistor differs in phase with the applied voltage by what angle?

Accepted Answer

A)  180° 
B)  zero 
C)  90° 
D)  45°

Question 5

The primary winding of an electric train transformer has 200 turns, and the secondary has 50. If the input voltage is 120 V(rms), what is the output voltage?

Accepted Answer

A)  30 V 
B)  15 V 
C)  10 V 
D)  480 V

Question 6

In an LCR series circuit the capacitive reactance is 24 $\Omega$. If the AC frequency halves, what will be the resulting capacitive reactance?

Accepted Answer

A)  24 $\Omega$ 
B)  48 $\Omega$ 
C)  12 $\Omega$ 
D)  Additional information is need to find the value.

Question 7

In an AC series circuit the inductive reactance is 150 $\Omega$ and the frequency is 100 Hz. What is the inductance in the circuit?

Accepted Answer

A)  740 mH 
B)  80 mH 
C)  500 mH 
D)  240 mH

Question 8

A resistor, inductor, and capacitor are connected in series, each with an effective (rms) voltage of 65 V, 140 V, and 90 V, respectively. What is the magnitude of the phase angle between the current and applied voltage phasors in this circuit?

Accepted Answer

A)  38° 
B)  28° 
C)  22° 
D)  43°

Question 9

When a 50-$\mu$F capacitor is attached to an AC source, its capacitive reactance is 60 $\Omega$. If instead a 200-$\mu$F capacitor is attached to the same source, what will be its capacitive reactance?

Accepted Answer

A)  80 $\Omega$ 
B)  15 $\Omega$ 
C)  30 $\Omega$ 
D)  120 $\Omega$

Question 10

In an AC series circuit the capacitive reactance is 253 $\Omega$ and frequency is 100 Hz. What is the capacitance?

Accepted Answer

A)  6.29 $\mu$F 
B)  8.0 $\mu$F 
C)  50.0 $\mu$F 
D)  3.2$\mu$F

Question 11

A 400-$\Omega$resistor and a capacitor are connected in parallel across a 300-Hz source. If the amplitude of the current in the resistor is equal to that in the capacitor, what is the value of the capacitance?

Accepted Answer

A)   
B)   
C)   
D)  0.212 F

Question 12

A 17.0-$\mu$F capacitor is connected to an AC source with an rms voltage of 120 V and a frequency of 60.0 Hz. What is the rms current in the capacitor?

Accepted Answer

A)  1.41 A 
B)  0.543 A 
C)  0 A 
D)  0.769 A

Question 13

Which of the following combinations of circuit components can be used to make a tuner for a radio, to select the desired frequency?

Accepted Answer

A)  fixed capacitor, variable resistor 
B)  fixed resistor, variable inductor 
C)  fixed inductor, variable capacitor 
D)  fixed inductor, variable resistor

Question 14

What is the impedance of an AC series circuit that is constructed of a 10.0-$\Omega$ resistor along with 24.0-$\Omega$ inductive reactance and 7.0-$\Omega$ capacitive reactance?

Accepted Answer

A)  19.7 $\Omega$ 
B)  11.2 $\Omega$ 
C)  41.0 $\Omega$ 
D)  27.7 $\Omega$

Question 15

Consider an AC series circuit containing a coil, capacitor, and resistor. Doubling the frequency will change the circuit's impedance by what factor?

Accepted Answer

A)  2.0 
B)  1.0 
C)  1/2 
D)  Information is insufficient to determine answer.

Question 16

In an RL circuit, which of the following is a possible magnitude of a phase angle?

Accepted Answer

A)  45° 
B)  315° 
C)  225° 
D)  135°

Question 17

Consider an AC series circuit containing a coil, capacitor, and resistor. Doubling the frequency will change the capacitive reactance by what factor?

Accepted Answer

A)  1.41 
B)  1.0 
C)  2.0 
D)  1/2

Question 18

An AC series circuit contains a resistor of 20 $\Omega$, an inductor of 50 mH, and a variable capacitor. If the frequency of the applied voltage is 500 Hz, to what setting should the capacitor be set if resonance is achieved?

Accepted Answer

A)  2.4 µF 
B)  3.4 µF 
C)  2.0 µF 
D)  0.8 µF

Question 19

An AC voltage source, with a peak output of 200 V, is connected to a 25-$\Omega$ resistor. What is the effective (or rms) current in the circuit?

Accepted Answer

A)  2.8 A 
B)  5.7 A 
C)  4.0 A 
D)  2.0 A

Question 20

A series circuit has equal values for resistance, capacitive reactance, and inductive reactance. The phase angle for this circuit is:

Accepted Answer

A)  180°. 
B)  -60°. 
C)  60°. 
D)  not given.

Exam 22: Alternating-Current Circuits and Machines

A transformer is used to step up the voltage to a power line. If the stepped-up voltage is 10 times the original value, by how much will the power loss in the line decrease?

A resistor, inductor, and capacitor are connected in series, each with effective (rms) voltage of 65 V, 150 V, and 80 V, respectively. What is the value of the effective (rms) voltage of the applied source in the circuit?

The frequency in an AC series circuit is halved. By what factor does this change the capacitive reactance?

In an AC series circuit, the current in a pure resistor differs in phase with the applied voltage by what angle?

The primary winding of an electric train transformer has 200 turns, and the secondary has 50. If the input voltage is 120 V(rms) , what is the output voltage?

In an LCR series circuit the capacitive reactance is 24 $\Omega$ . If the AC frequency halves, what will be the resulting capacitive reactance?

In an AC series circuit the inductive reactance is 150 $\Omega$ and the frequency is 100 Hz. What is the inductance in the circuit?

A resistor, inductor, and capacitor are connected in series, each with an effective (rms) voltage of 65 V, 140 V, and 90 V, respectively. What is the magnitude of the phase angle between the current and applied voltage phasors in this circuit?

When a 50- $\mu$ F capacitor is attached to an AC source, its capacitive reactance is 60 $\Omega$ . If instead a 200- $\mu$ F capacitor is attached to the same source, what will be its capacitive reactance?

In an AC series circuit the capacitive reactance is 253 $\Omega$ and frequency is 100 Hz. What is the capacitance?

A 400- $\Omega$ resistor and a capacitor are connected in parallel across a 300-Hz source. If the amplitude of the current in the resistor is equal to that in the capacitor, what is the value of the capacitance?

A 17.0- $\mu$ F capacitor is connected to an AC source with an rms voltage of 120 V and a frequency of 60.0 Hz. What is the rms current in the capacitor?

Which of the following combinations of circuit components can be used to make a tuner for a radio, to select the desired frequency?

What is the impedance of an AC series circuit that is constructed of a 10.0- $\Omega$ resistor along with 24.0- $\Omega$ inductive reactance and 7.0- $\Omega$ capacitive reactance?

Consider an AC series circuit containing a coil, capacitor, and resistor. Doubling the frequency will change the circuit's impedance by what factor?

In an RL circuit, which of the following is a possible magnitude of a phase angle?

Consider an AC series circuit containing a coil, capacitor, and resistor. Doubling the frequency will change the capacitive reactance by what factor?

An AC series circuit contains a resistor of 20 $\Omega$ , an inductor of 50 mH, and a variable capacitor. If the frequency of the applied voltage is 500 Hz, to what setting should the capacitor be set if resonance is achieved?

An AC voltage source, with a peak output of 200 V, is connected to a 25- $\Omega$ resistor. What is the effective (or rms) current in the circuit?

A series circuit has equal values for resistance, capacitive reactance, and inductive reactance. The phase angle for this circuit is:

Exam 22: Alternating-Current Circuits and Machines

A transformer is used to step up the voltage to a power line. If the stepped-up voltage is 10 times the original value, by how much will the power loss in the line decrease?

A resistor, inductor, and capacitor are connected in series, each with effective (rms) voltage of 65 V, 150 V, and 80 V, respectively. What is the value of the effective (rms) voltage of the applied source in the circuit?

The frequency in an AC series circuit is halved. By what factor does this change the capacitive reactance?

In an AC series circuit, the current in a pure resistor differs in phase with the applied voltage by what angle?

The primary winding of an electric train transformer has 200 turns, and the secondary has 50. If the input voltage is 120 V(rms) , what is the output voltage?

In an LCR series circuit the capacitive reactance is 24 Ω\OmegaΩ . If the AC frequency halves, what will be the resulting capacitive reactance?

In an AC series circuit the inductive reactance is 150 Ω\OmegaΩ and the frequency is 100 Hz. What is the inductance in the circuit?

A resistor, inductor, and capacitor are connected in series, each with an effective (rms) voltage of 65 V, 140 V, and 90 V, respectively. What is the magnitude of the phase angle between the current and applied voltage phasors in this circuit?

When a 50- μ\muμ F capacitor is attached to an AC source, its capacitive reactance is 60 Ω\OmegaΩ . If instead a 200- μ\muμ F capacitor is attached to the same source, what will be its capacitive reactance?

In an AC series circuit the capacitive reactance is 253 Ω\OmegaΩ and frequency is 100 Hz. What is the capacitance?

A 400- Ω\OmegaΩ resistor and a capacitor are connected in parallel across a 300-Hz source. If the amplitude of the current in the resistor is equal to that in the capacitor, what is the value of the capacitance?

A 17.0- μ\muμ F capacitor is connected to an AC source with an rms voltage of 120 V and a frequency of 60.0 Hz. What is the rms current in the capacitor?

Which of the following combinations of circuit components can be used to make a tuner for a radio, to select the desired frequency?

What is the impedance of an AC series circuit that is constructed of a 10.0- Ω\OmegaΩ resistor along with 24.0- Ω\OmegaΩ inductive reactance and 7.0- Ω\OmegaΩ capacitive reactance?

Consider an AC series circuit containing a coil, capacitor, and resistor. Doubling the frequency will change the circuit's impedance by what factor?

In an RL circuit, which of the following is a possible magnitude of a phase angle?

Consider an AC series circuit containing a coil, capacitor, and resistor. Doubling the frequency will change the capacitive reactance by what factor?

An AC series circuit contains a resistor of 20 Ω\OmegaΩ , an inductor of 50 mH, and a variable capacitor. If the frequency of the applied voltage is 500 Hz, to what setting should the capacitor be set if resonance is achieved?

An AC voltage source, with a peak output of 200 V, is connected to a 25- Ω\OmegaΩ resistor. What is the effective (or rms) current in the circuit?

A series circuit has equal values for resistance, capacitive reactance, and inductive reactance. The phase angle for this circuit is:

In an LCR series circuit the capacitive reactance is 24 $\Omega$ . If the AC frequency halves, what will be the resulting capacitive reactance?

In an AC series circuit the inductive reactance is 150 $\Omega$ and the frequency is 100 Hz. What is the inductance in the circuit?

When a 50- $\mu$ F capacitor is attached to an AC source, its capacitive reactance is 60 $\Omega$ . If instead a 200- $\mu$ F capacitor is attached to the same source, what will be its capacitive reactance?

In an AC series circuit the capacitive reactance is 253 $\Omega$ and frequency is 100 Hz. What is the capacitance?

A 400- $\Omega$ resistor and a capacitor are connected in parallel across a 300-Hz source. If the amplitude of the current in the resistor is equal to that in the capacitor, what is the value of the capacitance?

A 17.0- $\mu$ F capacitor is connected to an AC source with an rms voltage of 120 V and a frequency of 60.0 Hz. What is the rms current in the capacitor?

What is the impedance of an AC series circuit that is constructed of a 10.0- $\Omega$ resistor along with 24.0- $\Omega$ inductive reactance and 7.0- $\Omega$ capacitive reactance?

An AC series circuit contains a resistor of 20 $\Omega$ , an inductor of 50 mH, and a variable capacitor. If the frequency of the applied voltage is 500 Hz, to what setting should the capacitor be set if resonance is achieved?

An AC voltage source, with a peak output of 200 V, is connected to a 25- $\Omega$ resistor. What is the effective (or rms) current in the circuit?