Test Bank For Alternating Current Fundamentals
Chapter 1
CHAPTER 1 — INTRODUCTION TO ALTERNATING CURRENT
TRUE/FALSE
1. Direct current is used for various electrochemical processes, including electroplating, refining of
copper and aluminum, electrotyping, production of industrial gases by electrolysis, and charging of
storage batteries.
ANS: T PTS: 1 REF: 2
2. A basic knowledge of trigonometry is essential to an understanding of alternating-current concepts.
ANS: T PTS: 1 REF: 5
3. If the generator has two pairs of poles, then a cycle is generated every half-revolution, or 2 hertz per
second.
ANS: T PTS: 1 REF: 16
4. Alternating-voltage waveforms are all sine waves.
ANS: F PTS: 1 REF: 18
5. In electronics, the frequencies used cover a very narrow range.
ANS: F PTS: 1 REF: 19
COMPLETION
1. Traction motors require ____________________ current.
ANS: direct
PTS: 1 REF: 2
2. The commutators of dc generators are usually rated at less than ____________________ amperes (A).
ANS: 8000
PTS: 1 REF: 3
3. The use of ____________________’s generator rule shows that an alternating voltage is generated in
the coil as it rotates.
ANS: Fleming
1
, Test Bank For Alternating Current Fundamentals
Chapter 1
PTS: 1 REF: 10
4. One ____________________ represents an amount of magnetic flux equal to 100,000,000 lines.
ANS: weber
PTS: 1 REF: 10
5. Most ac generators have ____________________ field windings.
ANS: rotating
PTS: 1 REF: 11
SHORT ANSWER
1. The amount of voltage induced in a conductor is proportional to what three factors?
ANS:
1. The strength of the magnetic field (flux density)
2. The length of the conductor (often expressed as the number of turns of wire)
3. The speed of the cutting action
PTS: 1 REF: 10
2. Define alternating voltage.
ANS:
Alternating voltage may be defined as an electromotive force that changes continuously with time. It
rises from zero to a maximum value in one direction and decreases back to zero. It then rises to the
same maximum value in the opposite direction and again decreases to zero. These values are repeated
again and again at equal intervals of time.
PTS: 1 REF: 15
3. What is the definition of alternating current?
ANS:
Alternating current is a current that changes continuously with time. It rises from zero to a maximum
value in one direction and decreases back to zero. It then rises to the same maximum value in the
opposite direction and again decreases to zero. These values are repeated again and again at equal
intervals of time.
PTS: 1 REF: 15
4. What is the advantage of using a higher-frequency?
2
, Test Bank For Alternating Current Fundamentals
Chapter 1
ANS:
In the United States and Canada, 60 Hz is used almost exclusively, with the exception of a few areas
that use 25-Hz service. The advantage to using a higher-frequency service is that less iron and copper
are required in the transformers. Therefore, they are lighter and lower in cost. Also, incandescent
lamps operating at 60 Hz have no noticeable flicker. At 25 Hz, the flicker of incandescent lamps can
be annoying.
PTS: 1 REF: 15
5. Identify and explain the formula used to express the frequency of an ac generator.
ANS:
f = P X S/60
where
f = frequency, in hertz
P = number of pairs of poles
S = speed, in revolutions per minute (r/min)
60 = number of seconds in one minute
PTS: 1 REF: 16
3
, Test Bank For Alternating Current Fundamentals
Chapter 2
CHAPTER 2 — ALTERNATING -CURRENT CIRCUITS CONTAINING RESISTANCE
TRUE/FALSE
1. The product of effective volts and effective amperes is less than the power in watts in any ac circuit
having a noninductive resistance load where the current and the voltage are in phase.
ANS: F PTS: 1 REF: 32
2. The dc voltmeter has a d’Arsonval movement, which operates on the same principle as a dc motor.
ANS: T PTS: 1 REF: 35
3. Full-wave rectifiers eliminate one half of the waveform and retain the other.
ANS: F PTS: 1 REF: 35
4. Some manufacturers of dc instruments modify the circuit connections and the scale calibrations to
measure ac voltages and currents.
ANS: T PTS: 1 REF: 36
5. The voltage ratings of solid state devices are given as PIV (peak inverse voltage) or PRV (peak reverse
voltage).
ANS: T PTS: 1 REF: 37
COMPLETION
1. When the current and the voltage waveforms of a circuit are zero at the same time and reach their
maximum values at the same time and in the same direction, these waves are said to be in
____________________.
ANS: phase
PTS: 1 REF: 24
2. ____________________’s law states that the current in a resistor is directly proportional to the voltage
and inversely proportional to the magnitude of the resistance of the circuit.
ANS: Ohm
PTS: 1 REF: 24
3. The RMS value of current is the current indicated by the typical ____________________.
4
Chapter 1
CHAPTER 1 — INTRODUCTION TO ALTERNATING CURRENT
TRUE/FALSE
1. Direct current is used for various electrochemical processes, including electroplating, refining of
copper and aluminum, electrotyping, production of industrial gases by electrolysis, and charging of
storage batteries.
ANS: T PTS: 1 REF: 2
2. A basic knowledge of trigonometry is essential to an understanding of alternating-current concepts.
ANS: T PTS: 1 REF: 5
3. If the generator has two pairs of poles, then a cycle is generated every half-revolution, or 2 hertz per
second.
ANS: T PTS: 1 REF: 16
4. Alternating-voltage waveforms are all sine waves.
ANS: F PTS: 1 REF: 18
5. In electronics, the frequencies used cover a very narrow range.
ANS: F PTS: 1 REF: 19
COMPLETION
1. Traction motors require ____________________ current.
ANS: direct
PTS: 1 REF: 2
2. The commutators of dc generators are usually rated at less than ____________________ amperes (A).
ANS: 8000
PTS: 1 REF: 3
3. The use of ____________________’s generator rule shows that an alternating voltage is generated in
the coil as it rotates.
ANS: Fleming
1
, Test Bank For Alternating Current Fundamentals
Chapter 1
PTS: 1 REF: 10
4. One ____________________ represents an amount of magnetic flux equal to 100,000,000 lines.
ANS: weber
PTS: 1 REF: 10
5. Most ac generators have ____________________ field windings.
ANS: rotating
PTS: 1 REF: 11
SHORT ANSWER
1. The amount of voltage induced in a conductor is proportional to what three factors?
ANS:
1. The strength of the magnetic field (flux density)
2. The length of the conductor (often expressed as the number of turns of wire)
3. The speed of the cutting action
PTS: 1 REF: 10
2. Define alternating voltage.
ANS:
Alternating voltage may be defined as an electromotive force that changes continuously with time. It
rises from zero to a maximum value in one direction and decreases back to zero. It then rises to the
same maximum value in the opposite direction and again decreases to zero. These values are repeated
again and again at equal intervals of time.
PTS: 1 REF: 15
3. What is the definition of alternating current?
ANS:
Alternating current is a current that changes continuously with time. It rises from zero to a maximum
value in one direction and decreases back to zero. It then rises to the same maximum value in the
opposite direction and again decreases to zero. These values are repeated again and again at equal
intervals of time.
PTS: 1 REF: 15
4. What is the advantage of using a higher-frequency?
2
, Test Bank For Alternating Current Fundamentals
Chapter 1
ANS:
In the United States and Canada, 60 Hz is used almost exclusively, with the exception of a few areas
that use 25-Hz service. The advantage to using a higher-frequency service is that less iron and copper
are required in the transformers. Therefore, they are lighter and lower in cost. Also, incandescent
lamps operating at 60 Hz have no noticeable flicker. At 25 Hz, the flicker of incandescent lamps can
be annoying.
PTS: 1 REF: 15
5. Identify and explain the formula used to express the frequency of an ac generator.
ANS:
f = P X S/60
where
f = frequency, in hertz
P = number of pairs of poles
S = speed, in revolutions per minute (r/min)
60 = number of seconds in one minute
PTS: 1 REF: 16
3
, Test Bank For Alternating Current Fundamentals
Chapter 2
CHAPTER 2 — ALTERNATING -CURRENT CIRCUITS CONTAINING RESISTANCE
TRUE/FALSE
1. The product of effective volts and effective amperes is less than the power in watts in any ac circuit
having a noninductive resistance load where the current and the voltage are in phase.
ANS: F PTS: 1 REF: 32
2. The dc voltmeter has a d’Arsonval movement, which operates on the same principle as a dc motor.
ANS: T PTS: 1 REF: 35
3. Full-wave rectifiers eliminate one half of the waveform and retain the other.
ANS: F PTS: 1 REF: 35
4. Some manufacturers of dc instruments modify the circuit connections and the scale calibrations to
measure ac voltages and currents.
ANS: T PTS: 1 REF: 36
5. The voltage ratings of solid state devices are given as PIV (peak inverse voltage) or PRV (peak reverse
voltage).
ANS: T PTS: 1 REF: 37
COMPLETION
1. When the current and the voltage waveforms of a circuit are zero at the same time and reach their
maximum values at the same time and in the same direction, these waves are said to be in
____________________.
ANS: phase
PTS: 1 REF: 24
2. ____________________’s law states that the current in a resistor is directly proportional to the voltage
and inversely proportional to the magnitude of the resistance of the circuit.
ANS: Ohm
PTS: 1 REF: 24
3. The RMS value of current is the current indicated by the typical ____________________.
4
