Question 1

Which circuit elements act to oppose changes in the current in an ac circuit?

Accepted Answer

A) resistors only 
B) capacitors only 
C) inductors only 
D) both resistors and inductors 
E) both capacitors and resistors 
A) resistors only 
B) capacitors only 
C) inductors only 
D) both resistors and inductors 
E) both capacitors and resistors

Question 2

An oscillating LC circuit has a resonant frequency of 1.2 × 10S1U1P16 S1S1P0Hz. The diagram shows the system at t = 0 s when there is no charge on the capacitor and the current is in the direction shown. At this time, the energy stored in the inductor is 2.5 × 10S1U1P1-S1S1P0S1U1P17 S1S1P0J.  
-Determine the value of the current at the instant shown in the drawing.

Accepted Answer

A) 0.02 A 
B) 0.03 A 
C) 0.05 A 
D) 0.09 A 
E) 0.12 A 
A) 0.02 A 
B) 0.03 A 
C) 0.05 A 
D) 0.09 A 
E) 0.12 A

Question 3

The graph shows the impedance as a function of frequency for a series RCL circuit. At what frequency does the capacitor make the largest contribution?

Accepted Answer

A) f1 
B) f2 
C) f3 
D) f1 or f3 
E) f1 or f2 or f3 
A) f1 
B) f2 
C) f3 
D) f1 or f3 
E) f1 or f2 or f3

Question 4

A variable capacitor is connected to an ac source. What effect does decreasing the capacitance have on the reactance and current in this circuit?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 5

Use the information given in the figure for the series RCL circuit to determine its total impedance.

Accepted Answer

A) 300 $\varOmega$ 
B) 500 $\varOmega$ 
C) 1500 $\varOmega$ 
D) 1700 $\varOmega$ 
E) 1900 $\varOmega$ 
A) 300 $\varOmega$ 
B) 500 $\varOmega$ 
C) 1500 $\varOmega$ 
D) 1700 $\varOmega$ 
E) 1900 $\varOmega$

Question 6

For which one of the following circuit arrangements will the power factor be non-zero?

Accepted Answer

A) a capacitor in series with an ac generator 
B) an inductor in series with an ac generator 
C) two capacitors in series with an ac generator 
D) a capacitor and resistor in series with an ac generator 
E) a capacitor and inductor in series with an ac generator 
A) a capacitor in series with an ac generator 
B) an inductor in series with an ac generator 
C) two capacitors in series with an ac generator 
D) a capacitor and resistor in series with an ac generator 
E) a capacitor and inductor in series with an ac generator

Question 7

An oscillating LC circuit has a resonant frequency of 1.2 × 10S1U1P16 S1S1P0Hz. The diagram shows the system at t = 0 s when there is no charge on the capacitor and the current is in the direction shown. At this time, the energy stored in the inductor is 2.5 × 10S1U1P1-S1S1P0S1U1P17 S1S1P0J.  
-Determine the numerical value of the capacitance.

Accepted Answer

A) 2.4 × 10-11 F 
B) 3.6 × 10-11 F 
C) 4.4 × 10-11 F 
D) 6.8 × 10-11 F 
E) 8.8 × 10-11 F 
A) 2.4 × 10-11 F 
B) 3.6 × 10-11 F 
C) 4.4 × 10-11 F 
D) 6.8 × 10-11 F 
E) 8.8 × 10-11 F

Question 8

Use the information given in the figure for the series RCL circuit to determine the phase angle between the current and the voltage.

Accepted Answer

A) zero degrees 
B) +5.3° 
C) -9.6° 
D) -84° 
E) +90° 
A) zero degrees 
B) +5.3° 
C) -9.6° 
D) -84° 
E) +90°

Question 9

What is the inductance of the inductor in a series RCL circuit with a resonant frequency of 640 Hz if the only other element in the circuit is a 1.2-µF capacitor?

Accepted Answer

A) 52 mH 
B) 74 mH 
C) 0.12 H 
D) 2.1 H 
E) 13 H 
A) 52 mH 
B) 74 mH 
C) 0.12 H 
D) 2.1 H 
E) 13 H

Question 10

The following table gives the reactance and rms voltage across the elements of a series RCL circuit:  
-Determine the peak (not rms) voltage of the ac generator.

Accepted Answer

A) 150 V 
B) 212 V 
C) 300 V 
D) 414 V 
E) 533 V 
A) 150 V 
B) 212 V 
C) 300 V 
D) 414 V 
E) 533 V

Question 11

In an ac circuit, a 0.055-H inductor is connected to a generator that has an rms voltage of 18 V and operates at 50.0 Hz. What is the rms current through the inductor?

Accepted Answer

A) 0.62 A 
B) 2.0 A 
C) 3.2 A 
D) 1.0 A 
E) 14 A 
A) 0.62 A 
B) 2.0 A 
C) 3.2 A 
D) 1.0 A 
E) 14 A

Question 12

An ac generator is connected across the terminals of a 3.25-µF capacitor. Determine the frequency at which the capacitive reactance is 375 $\varOmega$.

Accepted Answer

A) 60.0 Hz 
B) 72.4 Hz 
C) 85.7 Hz 
D) 98.9 Hz 
E) 131 Hz 
A) 60.0 Hz 
B) 72.4 Hz 
C) 85.7 Hz 
D) 98.9 Hz 
E) 131 Hz

Question 13

Two 250-µF capacitors and a 1.5-mH inductor are connected as shown in the figure. It is desired to "drive" the circuit by placing an ac generator in series with the inductor. Which one of the following generator output voltages will produce the largest current in the above circuit? Assume that V is in volts when t is in seconds.

Accepted Answer

A) V = 0.6 sin[(1.1 × 106 rad/s)t] 
B) V = 0.6 sin[(1.2 × 103 rad/s)t] 
C) V = 1.2 sin[(5.3 × 106 rad/s)t] 
D) V = 1.2 sin[(2.3 × 105 rad/s)t] 
E) V = 2.8 sin[(4.6 × 106 rad/s)t] 
A) V = 0.6 sin[(1.1 × 106 rad/s)t] 
B) V = 0.6 sin[(1.2 × 103 rad/s)t] 
C) V = 1.2 sin[(5.3 × 106 rad/s)t] 
D) V = 1.2 sin[(2.3 × 105 rad/s)t] 
E) V = 2.8 sin[(4.6 × 106 rad/s)t]

Question 14

Which one of the following graphs shows how the inductive reactance varies with frequency?

Accepted Answer

A) a 
B) b 
C) c 
D) d 
E) e 
A) a 
B) b 
C) c 
D) d 
E) e

Question 15

Which one of the following statements concerning an ac circuit is true?

Accepted Answer

A) The current and voltage are in phase for a capacitor in an ac circuit. 
B) On average, the power dissipated by a resistor in an ac circuit is zero. 
C) For a resistor in an ac circuit, the current and voltage are 90° out of phase. 
D) Inductors in an ac circuit offer little opposition to current at high frequencies. 
E) When only resistance is present in an ac circuit, voltage and current are in phase. 
A) The current and voltage are in phase for a capacitor in an ac circuit. 
B) On average, the power dissipated by a resistor in an ac circuit is zero. 
C) For a resistor in an ac circuit, the current and voltage are 90° out of phase. 
D) Inductors in an ac circuit offer little opposition to current at high frequencies. 
E) When only resistance is present in an ac circuit, voltage and current are in phase.

Question 16

An ac generator supplies a peak (not rms) voltage of 120.0 V at 60.0 Hz. It is connected in series with a 50.0-$\varOmega$ resistor and a 0.500-H inductor.
-What is the average power dissipated in the circuit?

Accepted Answer

A) 9.50 W 
B) 21.2 W 
C) 74.9 W 
D) 113 W 
E) 138 W 
A) 9.50 W 
B) 21.2 W 
C) 74.9 W 
D) 113 W 
E) 138 W

Question 17

An ac generator supplies an rms (not peak) voltage of 180 V at 60.0 Hz. The generator is connected in series with a 0.50-H inductor, a 6.0-µF capacitor and a 300-$\varOmega$ resistor.
-What is the peak (not rms) voltage across the capacitor?

Accepted Answer

A) 120 V 
B) 180 V 
C) 190 V 
D) 210 V 
E) 290 V 
A) 120 V 
B) 180 V 
C) 190 V 
D) 210 V 
E) 290 V

Question 18

An ac generator supplies an rms (not peak) voltage of 180 V at 60.0 Hz. The generator is connected in series with a 0.50-H inductor, a 6.0-µF capacitor and a 300-$\varOmega$ resistor.
-Determine the peak voltage of the generator.

Accepted Answer

A) 180 V 
B) 255 V 
C) 300 V 
D) 360 V 
E) 480 V 
A) 180 V 
B) 255 V 
C) 300 V 
D) 360 V 
E) 480 V

Question 19

Two series RCL circuits have the same resonant frequency. Circuit A has an inductance of 0.55 H and circuit B has an inductance of 0.15 H. Determine the ratio of the capacitances of the circuits, CA/CB.

Accepted Answer

A) 0.44 
B) 0.27 
C) 3.7 
D) 1.8 
E) 2.4 
A) 0.44 
B) 0.27 
C) 3.7 
D) 1.8 
E) 2.4

Question 20

A variable inductor is connected to an ac source. What effect does increasing the inductance have on the reactance and current in this circuit?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Exam 23: Alternating Current Circuits

Which circuit elements act to oppose changes in the current in an ac circuit?

The graph shows the impedance as a function of frequency for a series RCL circuit. At what frequency does the capacitor make the largest contribution?

A variable capacitor is connected to an ac source. What effect does decreasing the capacitance have on the reactance and current in this circuit?

Use the information given in the figure for the series RCL circuit to determine its total impedance.

For which one of the following circuit arrangements will the power factor be non-zero?

Use the information given in the figure for the series RCL circuit to determine the phase angle between the current and the voltage.

What is the inductance of the inductor in a series RCL circuit with a resonant frequency of 640 Hz if the only other element in the circuit is a 1.2-µF capacitor?

The following table gives the reactance and rms voltage across the elements of a series RCL circuit: -Determine the peak (not rms) voltage of the ac generator.

In an ac circuit, a 0.055-H inductor is connected to a generator that has an rms voltage of 18 V and operates at 50.0 Hz. What is the rms current through the inductor?

An ac generator is connected across the terminals of a 3.25-µF capacitor. Determine the frequency at which the capacitive reactance is 375 Ω\varOmegaΩ .

Which one of the following graphs shows how the inductive reactance varies with frequency?

Which one of the following statements concerning an ac circuit is true?

An ac generator supplies a peak (not rms) voltage of 120.0 V at 60.0 Hz. It is connected in series with a 50.0- Ω\varOmegaΩ resistor and a 0.500-H inductor. -What is the average power dissipated in the circuit?

An ac generator supplies an rms (not peak) voltage of 180 V at 60.0 Hz. The generator is connected in series with a 0.50-H inductor, a 6.0-µF capacitor and a 300- Ω\varOmegaΩ resistor. -What is the peak (not rms) voltage across the capacitor?

An ac generator supplies an rms (not peak) voltage of 180 V at 60.0 Hz. The generator is connected in series with a 0.50-H inductor, a 6.0-µF capacitor and a 300- Ω\varOmegaΩ resistor. -Determine the peak voltage of the generator.

Two series RCL circuits have the same resonant frequency. Circuit A has an inductance of 0.55 H and circuit B has an inductance of 0.15 H. Determine the ratio of the capacitances of the circuits, CA/CB.

A variable inductor is connected to an ac source. What effect does increasing the inductance have on the reactance and current in this circuit?

Introduction and Mathematical Concepts

Kinematics in One Dimension

Kinematics in Two Dimensions

Forces and Newtons Laws of Motion

Dynamics of Uniform Circular Motion

Work and Energy

Impulse and Momentum

Rotational Kinematics

Rotational Dynamics

Simple Harmonic Motion and Elasticity

Fluids

Temperature and Heat

The Transfer of Heat

The Ideal Gas Law and Kinetic Theory

Thermodynamics

Waves and Sound

The Principle of Linear Superposition and Interference Phenomena

Electric Forces and Electric Fields

Electric Potential Energy and the Electric Potential

Electric Circuits

Magnetic Forces and Magnetic Fields

Electromagnetic Induction

Electromagnetic Waves

The Refl Ection of Light: Mirrors

The Refraction of Light: Lenses and Optical Instruments

Interference and the Wave Nature of Light

Special Relativity

Particles and Waves

The Nature of the Atom

Nuclear Physics and Radioactivity

Ionizing Radiation, Nuclear Energy, and Elementary Particles

Filters

An ac generator is connected across the terminals of a 3.25-µF capacitor. Determine the frequency at which the capacitive reactance is 375 $\varOmega$ .

An ac generator supplies a peak (not rms) voltage of 120.0 V at 60.0 Hz. It is connected in series with a 50.0- $\varOmega$ resistor and a 0.500-H inductor. -What is the average power dissipated in the circuit?

An ac generator supplies an rms (not peak) voltage of 180 V at 60.0 Hz. The generator is connected in series with a 0.50-H inductor, a 6.0-µF capacitor and a 300- $\varOmega$ resistor. -What is the peak (not rms) voltage across the capacitor?

An ac generator supplies an rms (not peak) voltage of 180 V at 60.0 Hz. The generator is connected in series with a 0.50-H inductor, a 6.0-µF capacitor and a 300- $\varOmega$ resistor. -Determine the peak voltage of the generator.

Two series RCL circuits have the same resonant frequency. Circuit A has an inductance of 0.55 H and circuit B has an inductance of 0.15 H. Determine the ratio of the capacitances of the circuits, C_A/C_B.