A 1.38:1
B 1.67:1
C 0.72:1
D 0.60:1

A field
B flux
C coulomb
D weber

# Q3: Electricity may be generated by a wire:

A carrying current
B wrapped as a coil
C that has neutral domains
D passing through a flux field

A 0.001 degrees
B 2.300 degrees
C 87.600 degrees
D 89.900 degrees

# Q5: What does Faraday's law concern?

A a magnetic field in a coil
B a magnetic field cutting a conductor
C a magnetic field hystersis
D a magnetic field in a conductor

# Q6: Fixed transformers have:

A a center-tapped secondary
B multiple windings
C turns ratios that cannot be changed
D a multiple-tapped secondary

A
72.5 s
B
532 s
C
610 s
D
833 s

# Q8: What will happen when an inductor's magnetic field collapses?

A Current will double.
B Voltage will be induced.
C A new field will expand.
D Counter emf will be high.

# Q9: What is hysteresis?

A lead between cause and effect
B lag between cause and effect
C lead between voltage and current
D lag between voltage and current

A
0 s
B
5 s
C
15 s
D
25 s

A
4.76 mH
B
33.3 mH
C
98.0 mH
D
150.0 mH

A
5.0 W
B
1.25 pW
C
9.5 W
D
20.0 mW

A back emf
B self-induction
C a henry
D impedance

# Q14: Find VR and VL.

A
VR = 41.6 V, VL = 78.4 V
B
VR = 48 V, VL = 110 V
C
VR = 56 V, VL = 106 V
D
VR = 60 V, VL = 60 V

A 50
B 450
C 1500
D 5500

# Q16: Which two values are plotted on a B-H curve graph?

A reluctance and flux density
B permeability and reluctance
C magnetizing force and permeability
D flux density and magnetizing force

# Q17: A turns ratio of 5 for a transformer implies:

A more primary turns than secondary turns
B more secondary current than primary current
C larger source impedance than load impedance
D more secondary turns than primary turns

# Q18: Which coil would be used as a step-up transformer primary if coil number 1 has 100 more turns than coil number 2?

A The coil windings must be the same.
B coil 1
C The coil ratio is too small.
D coil 2

# Q19: The unit of flux density is:

A magnetomotive force
B a weber
C a maxwell
D a tesla

# Q20: When the transformer secondary is not loaded:

A secondary voltage increases
B no secondary current flows
C no secondary voltage is present
D secondary current increases

A reactance
B reluctance
C retentitivity
D resistance

# Q22: When current in an inductor starts to change, it cannot react instantly due to:

A fixed coil resistance
B eddy current generation
C applied emf of the circuit
D the counter emf of the coil

# Q23: A winding of wire can be called

A an inductor
B a coil
C a choke
D All of the above

# Q24: When an electromagnet reaches maximum strength, it is considered to be:

A in field condition
B at saturation
C inhibited
D at field strength

# Q25: A loaded transformer will achieve mutual induction when:

A secondary current increase causes a primary current decrease
B primary current is increased by an increase in secondary current
C primary current is decreased by an increase in secondary current
D secondary current decrease causes a primary current increase

# Q26: A transformer will have:

A primary and secondary windings
B primary and secondary current
C primary wattage producing secondary current
D different frequencies for the primary and secondary

A
1.1 x 10−4
B
5.65 x 10−4
C
6.9 x 10−3
D
8.8 x 10−3

A
12 mH
B
6 mH
C
0.73 mH
D
0 mH

# Q29: The electrical energy consumed by a coil is stored in the form of:

A an electrical field
B a force field
C an electrostatic field
D a magnetic field

# Q30: A henry value divided by a circuit resistive value provides the:

A counter emf value
B induced voltage amplitude
C rise or decay time constant
D quality factor of the coil

# Q31: In a transformer, what will happen to the primary current if the secondary magnetic field increases?

A
Ip will increase.
B
Ip will be canceled.
C
Ip will remain the same.
D
Ip will decrease.

A a lenz
B an ohm
D a henry

# Q33: What is electromagnetism?

A the magnetic field generated around a conductor when a current passes through it
B the magnetic field generated in a conductor by an external voltage
C the voltage caused by a magnetic field in a conductor
D the current generated by an external magnetic field

A
5.2
B
7.5
C
1.3 k
D
7.5 k

A
79.9 mA
B
126.4 mA
C
173.0 mA
D
198.6 mA

A
2.88 V
B
5.9 V
C
8.34 V
D
14 V

# Q37: Inductance is:

A directly proportional to the length of the coil
B directly proportional to the number of turns on the coil
C inversely proportional to the cross-sectional area of the coil
D inversely proportional to the permeability

# Q38: Which of the following represents a true equivalent of an inductor?

A An inductance in series with a resistance and a capacitance
B A capacitance in parallel with the series combination of a resistance and an inductance
C An inductance in parallel with the series combination of a resistance and a capacitance
D The only quality a real inductor has is inductance.

# Q39: If you wanted to decrease the inductance of a coil, you might increase the:

A number of turns
B permeability of the core
C spacing between turns
D area of the coil

# Q40: What term is used to describe the action of magnetic flux from one circuit that cuts across the conductors of another circuit?

A self-inductance
B rectification
C mutual inductance
D magnetism

# Q41: On a schematic, dashed lines between two vertical coils usually mean the transformer has:

A an air core
B an iron core
C a nonmetallic core
D a ferrite core

# Q42: The four factors determining inductance are the number of turns, coil length, coil area, and:

A permeability
B reluctance
C counter emf
D coefficient of coupling

A 75 turns
B 150 turns
C 900 turns
D 1920 turns

A
2 A
B
5 A
C
10 A
D
20 A

# Q45: The output phase for a transformer is:

A in phase with the input
B out of phase with the input
C dependent on the direction of the primary and secondary windings
D dependent on the frequency of the primary source

# Q46: When used as a filter, an inductor is

A placed in series with the load and aids any current changes
B placed in parallel with the load and aids any current changes
C placed in parallel with the load and opposes any current changes
D placed in series with the load and opposes any current changes

A
500 ohms
B
1000 ohms
C
1414 ohms
D
2000 ohms

# Q48: In a B-H curve, magnetizing force is equal to:

A
B
H = I × N
C
ampere-turns per weber
D
webers per square meter

# Q49: A transformer is used:

A to couple electric energy from one dc circuit to another
B to couple electric energy from an ac circuit to a dc circuit
C to couple electric energy from a dc circuit to an ac circuit
D to couple electric energy from one ac circuit to another

# Q50: When a coil collapses the induced circuit current will:

A be in the same direction
B go to zero
C aid counter emf buildup
D be in the opposite direction

# Q51: Find IR and IL.

A
IR = 50 mA, IL = 109 mA
B
IR = 150 mA, IL = 9 mA
C
IR = 50 mA, IL = 151 mA
D
IR = 150 mA, IL = 53 mA

# Q52: Counter emf or induced voltage is:

A inversely proportional to the change in current
B directly proportional to the change in time
C directly proportional to the inductance in henrys
D inversely proportional to the inductance in henrys

# Q53: When a load is not connected to the secondary of a transformer:

A primary current is zero
B primary current is inversely proportional to primary impedance
C secondary voltage is zero
D secondary voltage is proportional to primary impedance

# Q54: A magnetic circuit breaker will open to protect equipment only when:

A voltage is exceeded
B an open is in the equipment
C the equipment is operating properly
D current is exceeded

# Q55: What is electromagnetism?

A the magnetic field generated around a conductor when a current passes through it
B the magnetic field generated in a conductor by an external voltage
C the voltage caused by a magnetic field in a conductor
D the current generated by an external magnetic field

# Q56: Electromagnetism is the:

A magnetic field caused by a permanent magnet
B action between a permanent and an artificial magnet
C magnetic field action with a current-carrying wire
D current in the coil

# Q57: A magnetic field has:

A polar fields
B lines of force
C magnetomotive force
D lines of reluctance

# Q58: What are the properties that determine the inductance of a coil?

A Length of wire, number of turns, type of core material, length of core
B Number of turns, type of wire, length of core, and cross-sectional area of core
C Type of core material, number of turns, cross-sectional area of core, and length of core
D Type of core material, type of wire, number of turns, and cross-sectional area of core

# Q59: Opposition to current flow without the dissipation of energy is called:

A resistance
B inductive reactance
C counter emf
D impedance

# Q60: What is magnetic flux?

A the number of lines of force in webers
B the number of lines of force in maxwells
C the number of lines of force in teslas
D the number of lines of force in flux density

# Q61: When a transformer secondary lead has been connected to a middle loop that is not an end connector, it is called a:

A multiple-tapped secondary
B center-tapped secondary
C multiple winding secondary
D single winding secondary

# Q62: What happens when moving expanding lines of force encounter a conductor?

A Current increases.
B Voltage is induced.
C Resistance is reduced.
D Power is increased.

# Q63: As current travels within a conductor:

A the magnetic field aids the current
B a magnetic field is developed around it
C the wire tries to point north
D an electrostatic field opposes the current

A
1500 mA
B
200 mA
C
167 mA
D
150 mA

# Q65: The time difference, or lag, between flux density and magnetizing force is known as:

A eddy current
B magnetic saturation
C hysteresis
D coercivity

# Q66: Faraday's law states that the:

A direction of the induced voltage produces an opposition
B direction of an induced current produces an aiding effect
C emf depends on the rate of cutting flux
D emf is related to the direction of the current

# Q67: When used as a filter, an inductor is

A placed in series with the load and aids any current changes
B placed in parallel with the load and aids any current changes
C placed in parallel with the load and opposes any current changes
D placed in series with the load and opposes any current changes

A 2.3 VAR
B 4.6 VAR
C 9.3 VAR
D 0 VAR

# Q69: Reactance in an inductive circuit will:

A increase with frequency
B decrease with frequency
C be independent from frequency
D
depend on the value of XC

# Q70: A practical inductor

A has inductance
B has winding resistance
C has winding capacitance
D all of the above

A air core
B ferrite core
C magnesium core
D iron core

# Q72: When a transformer secondary lead has been connected to a middle loop that is not an end connector, it is called a:

A multiple-tapped secondary
B center-tapped secondary
C multiple winding secondary
D single winding secondary

A
0.1 degrees
B
9.0 degrees
C
61.0 degrees
D
81.0 degrees

# Q74: A series RL filter circuit with an output across the inductor will result in what type of filtering?

A passing of the higher frequencies
B passing of the lower frequencies
C blocking of the higher frequencies
D blocking of a certain range of frequencies

# Q75: An inductor is in series with a voltage source, an open switch, and a resistor. The instant the switch is closed, the inductor acts like

A a short
B an open
C a resistor
D a voltage source

A
0 mH
B
0.69 mH
C
12 mH
D
24 mH

# Q77: When a magnet enters a coil and a voltage is induced, the process is known as:

A an alternation
B self-inductance
C counter emf

# Q78: As a generator armature passes the 270 degree point, the induced voltage is:

A at maximum negative
B between maximum negative and zero
C at maximum positive
D between zero and maximum positive

A
160 mH
B
300 mH
C
900 mH
D
1700 mH

# Q80: Electromagnetic induction is the generation of:

A electricity from magnetism
B electricity from electricity
C magnetism from electricity
D magnetism from magnetism

# Q81: The polarity of induced voltage while a field is collapsing is:

A independent of the force creating it
B opposite to the force creating it
C identical to the force creating the field
D present only if the force is stationary

A
0.083
B
12
C
30
D
300

# Q83: The time required for one weber of flux to cut a conductor and produce one volt is:

A one revolution
B one second
C one millisecond
D four revolutions

# Q84: The unit of flux density is:

A magnetomotive force
B a weber
C a maxwell
D a tesla

A solenoid
B reed switch
C relay
D armature

# Q86: A voltage is induced in a transformer secondary winding by the action of the:

A secondary magnetic field
B primary turns ratio
C primary magnetic field
D secondary counter emf

# Q87: Current will cause a magnetic field in a conductor as follows:

A An ac current causes a fixed polarity magnetic field.
B A dc current causes a fixed polarity magnetic field.
C A dc current causes an alternating magnetic field.
D An ac current causes a fixed polarity magnetic field and a dc current causes an alternating magnetic field.

A 10 seconds
B 8 seconds
C 4 seconds
D 2 seconds

# Q89: With a square wave input, an RL differentiator circuit with an output across the inductor will produce what type of waveform?

A dc
B short time-duration pulses
C exponential-shaped pulses
D only a phase shift

# Q90: In a purely inductive circuit,

A current leads voltage by 90°
B voltage lags current by 90°
C voltage leads current by 90°
D voltage and current are in phase (0°)

# Q91: A utility pole transformer used to supply a residential customer with two phases uses:

A two phases on the primary
B a center tap on the secondary
C a separate ground for each phase
D a small coefficient of coupling

A
2.4 Vac
B
150 Vac
C
180 Vac
D
720 Vac

A armature
B conductor
C contacts
D solenoid

# Q94: You could decrease the time constant of an RL circuit by

A adding a resistor in parallel with the circuit resistance
B adding an inductor in series with the circuit inductance
C decreasing the amplitude of the input voltage
D exchanging the position of the resistor and inductor in the circuit

A a lenz
B an ohm