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City Test Review
Review
130
Electrical Engineering
Post-Graduate
04/24/2024

Additional Electrical Engineering Flashcards

 


 

Cards

Term
If the contact resistance of a connection increases and the current of the circuit remains the same, the voltage dropped across the connection will ____.

a.increase
b.decrease
c.remain the same
d.cannot be determined
Definition
a. increase
Term
To double the current of a circuit when the voltage remains constant, the R (resistance) must be _____.

a.doubled
b.reduced by half
c.increased
d.none of these
Definition
b. reduced by half
Term
An ohmmeter is being used to test a relay coil. The equipment instructions indicate that the resistance of the coil should be between 30 and 33 ohms. The ohmmeter indicates the actual resistance is less than 22 ohms. This reading would most likely indicate _____.

a.the coil is okay
b.an open coil
c.a shorted coil
d.a meter problem
Definition
c. a shorted coil
Term
The energy consumed by a 5 ohm resistor is ____ than the energy consumed by a 10 ohm resistor, assuming the current in both cases remains the same.

a.more
b.less
Definition
b. less
Term
A 120V rated toaster will produce ____ heat when supplied by 115V.

a.more
b.less
c.the same
d.none of these
Definition
b. less
Term
When a 100W, 115V lamp operates at 230V, the lamp will consume approximately _____.

a.150W
b.300W
c.400W
d.450W
Definition
c. 400w

E^2 / p

15^2 / 100 = 132.25

230^2 / 132.25 = 400W
Term
A parallel circuit has two or more paths in which current can flow.

a.true
b.false
Definition
a. true
Term
In a parallel circuit, the voltage drop across each resistance is equal to the sum of the voltage drop each resistor in parallel.

a.true
b.false
Definition
b. false
Term
According to Kirchoff's current law, the total current provided by the source to a parallel circuit equals the sum of the currents of all the branches.

a.true
b.false
Definition
b. true
Term
In a parallel circuit, the total resistance is always greater than the smallest resistance.

a.true
b.false
Definition
b. false
Term
A series circuit has four 40 ohm resistors and the power supply is 120V. The voltage drop of each resistor will be ____.

a.1/4 of the source voltage
b.30V
c.the same across each resistor
d.all of these
Definition
a. all of these

*If you do the math its 30V
Term
The power consumed in a series circuit is ____.

a.the sum of the power consumed of each load
b.determined by the formula PT=I^2 x RT
c.determined by the formula PT=E x I
d.all of these
Definition
d. all of these
Term
A single phase, dual rated, 120/240V motor will have its winding connected in ____ when supplied by 120V.

a.series
b.parallel
c.series-parallel
d.parallel-series
Definition
b. parallel
Term
When a magnetic field moves through a coil of wire, the lines of force of the magnetic field cause the in wire to flow in a specific direction. When the magnetic field moves in the opposite direction, electrons in the wire flow in the opposite direction.

a.true
b.false
Definition
a. true
Term
Output voltage of a generator depends upon the ____.

a.number of turns of the wire
b.strength of the magnetic field
c.speed at which the coil rotates
d.all of these
Definition
d. all of these
Term
The waveform for ac circuits displays the
level and direction of the current and voltage for every instant of time for one full revolution of the rotor.

a.true
b.false
Definition
a. true
Term
The number of complete waveforms in one second is called the frequency. The frequency is expressed as ___ or cycles per second.

a.degrees
b.a sine wave
c.phase
d. hertz
Definition
d. hertz
Term
If the voltage waveform finishes before the current waveform, the voltage is said to ____ the current waveform.

a.lead
b.lag
c.be in-phase-with
d.none of these
Definition
a. lead
Term
When the current waveform finishes before the voltage waveform, the voltage is said to _____ the current waveform.

a.lead
b.lag
c.be in-phase-with
d.none of these
Definition
b. lag
Term
____ is a property of an electrical circuit that enables it to store electrical energy by means of an electric field and to release this energy at a later time.

a.capacitance
b.induction
c.self-induction
d.none of these
Definition
a. capacitance
Term
A capacitor is a device that resists changes in current. Because a capacitor introduces reactance to the circuit, it shifts the current waveform to ____.

a.lead the applied voltage by 90 degrees
b.lag the applied voltage by 90 degrees
c.lead the applied voltage by 180 degrees
d.lag the applied voltage by 180 degrees
Definition
a. lead the applied voltage by 90 degrees
Term
The opposition offered to the flow of ac current by a capacitor is called capacitive reactance, which is expressed in ohms and abbreviated ____.

a.XC
b.XL
c.Z
d.none of these
Definition
a. XC
Term
When electrons move, the magnetic fields of the individual electrons combine to produce an overall magnetic field. Eht greater than the current flow, the greater the overall magnetic field around the conductor.

a.true
b.false
Definition
a. true
Term
When alternating current increases, the polarity of the CEMF within the conductor tries to prevent current from increasing.

a.true
b.false
Definition
a. true
Term
When alternating current decreases, the polarity of the induced voltage within the conductor tries to prevent the current from decreasing.

a.true
b.false
Definition
a. true
Term
Conductor resistance is directly proportional to the conductor's length and cross sectional area.

a.true
b.false
Definition
b. false
Term
For ac circuits, the ____ of a conductor oppose(s) the current flow in the circuit.

a.Eddy currents
b.Skin effect
c.Resistance
d.All of these
Definition
d. All of these
Term
Eddy currents are small independent currents induced within the conductor because of direct current.

a.true
b.false
Definition
b. false
Term
The magnitude of seld-induced voltage within a winding is directly proportional to the current flow, the winding, and the frequency at which magnetic fields cut through the winding.

a.true
b.false
Definition
a. true
Term
Self induced voltage opposes the change in current flowing in the conductor. This called inductive reactance and is abbreviated _____.

a.XL
b.XC
c.Z
d.None of these
Definition
a. XL
Term
If you measure voltage and current in an inductive or capacitive circuit and the multiply them together, you obtain the circuit's ___.

a.true power
b.power factor
c.apparent power
d.none of these
Definition
c. apparent power
Term
True power of an ac circuit equals volts times amperes.

a.true
b.false
Definition
b. false
Term
A waveform represents _____.

a.the magnitude and direction of current or voltage.
b.how current or voltage can vary with time
c.how output voltage can vary with the generator armature
d.all of these
Definition
d. all of these
Term
The frequency of an ac waveform is the number of times the current of voltage goes through 360 degrees in ____.

a.1/10 second
b.1 second
c.5 seconds
d. 30 seconds
Definition
b. 1 second
Term
120V is the reading shown on a voltmeter. This is an indication of the ____ value of the voltage source.

a.average
b.peak
c.effective
d.instantaneous
Definition
c. effective
Term
In a circuit that has only capacitive reactance, the voltage and current are said to be out-of-phase to each other because the voltage ___.

a.leads the current by 90 degrees
b.lags the current by 90 degrees
c.leads the current
d.none of these
Definition
b. lags the current by 90 degrees
Term
Resonance occurs when ____.

a.Only resistance occurs in the system
b.the power factor is equal to zero
c.XL=XC
d.R=Z
Definition
c. XL=XC
Term
Capacitive reactance is measured in ____.

a.ohms
b.volts
c.watts
d.henrys
Definition
a. ohms
Term
Inductive reactance is abbreviated as ____.

a.I^2XR
b.LX
c.XL
d.Z
Definition
c. XL
Term
Inductive reactance is measured in ___.

a.farads
b.watts
c.ohms
d.coulombs
Definition
c. ohms
Term
The total opposition to current flow in an ac circuit is expressed in ohms and is called _____.

a.impedance
b.conductance
c.reluctance
d.none of these
Definition
a. impedance
Term
Conductor resistance to ac flow is _____ resistance to dc.

a.higher than
b.lower than
c.the same as
d.none of these
Definition
a. higher than
Term
If you multiply the voltage by the current in an inductive or capacitive circuit the answer will be the ____ of the circuit.

a.watts
b.true power
c.apparent power
d.all of these
Definition
c. apparent power
Term
If the speed of a shunt-wound dc motor begins to increase, the armature cuts through the electromagnetic field at an increasing rate. This results in a greater armature CEMF, which acts to cut down on the increased armature current, resulting in the motor speeding up.

a.true
b.false
Definition
b. false
Term
Placing a load on a shunt-wound dc motor causes the motor to slow down, which increases the rate at which the field flux lines are cut by the armature. As a result, the armature CEMF increases resulting in an increase in the applied armature voltage and current. The increase in current results in increased motor speed.

a.true
b.false
Definition
b. false
Term
To reverse the rotation of a dc motor, you must reverse the ____.

a.stator field
b.rotor field
c.A & B
d.A or B
Definition
d. A or B
Term
Swapping ____ of the line conductors can reverse a three phase ac motor's rotation.

a.one
b.two
c.three
d.four
Definition
b. two
Term
Autotransformers use separate windings for the primary and secondary.

a.true
b.false
Definition
b. false
Term
As current flows through the transformer, the iron core is temporarily magnetized. The energy required to realign the core molecules to the changing electromagnetic field is called _____.

a.conductor resistance
b.flux leakage
c.eddy currents
d.hysteresis loss
Definition
d. hysteresis loss
Term
A ______ is used to raise or lower voltage and it has the ability to transfer electrical energy from one system to another with no physical connection between the two systems.

a.capacitor
b.motor
c.relay
d.transformer
Definition
d. transformer
Term
The transformer winding that is connected to the source is called the ____ winding and the transformer winding that is connected to the load is called the ____.

a.secondary, primary
b.primary, secondary
c.depends on the wiring
d.none of these
Definition
b. primary, secondary
Term
If the primary phase voltage is 480V and the secondary phase voltage is 240V, the turns ratio is ____.

a.1:4
b.1:2
c.2:1
d.4:1
Definition
c. 2:1
Term
Transformers are related in ____.

a.henrys
b.kW
c.W
d.kVA
Definition
d. kVA
Term
If two line (supply) leads of a dc series motor are reversed, the motor will _____.

a.not run
b.run backwards
c.run the same as before
d.become a generator
Definition
c. run the same as before
Term
To reverse a dc series motor, we may simply reverse the supply (power) leads.

a.true
b.false
Definition
b. false
Term
The _____ induction motor is use only in special applications and is always operated on three phase ac power.

a.compound
b.synchronous
c.split phase
d.wound rotor
Definition
d. wound rotor
Term
The rotating part of a dc motor or generator is called the ____.

a.shaft
b.rotor
c.armature
d.B or C
Definition
c. B or C
Term
A transformer winding has a voltage turns ratio of 2:1, the current flowing through the secondary winding will be _____ the current flowing through the primary winding.

a.higher than
b.lower than
c.the same as
d.none of these
Definition
a. higher than
Term
If a transformer primary winding has 900 turns and the secondary winding has 90 turns, which winding of the transformer has a larger conductor in cross sectional area?

a.primary
b.secondary
c.interwinding
d.autowinding
Definition
b. secondary
Term
When a raceway does not exceed 24 in. in length, the raceway is permitted to be filled to ____ percent of its cross section area.

a.31
b.40
c.53
d.60
Definition
d. 60
Term
The number of conductors permitted in a raceway is dependent on ___.

a.area of the raceway
b.percent area fill as listed in chapter 9, table 1
c.area of the conductors as listed in chapter 9, tables 5 and 8
d.all of these
Definition
d. all of these
Term
Which of the following statements are true for a 10 hp, 208V, three phase motor with a nameplate current of 29A?

a.the branch circuit conductors can be 8 THHN.
b.overload protection is 33A
c.short circuit and ground fault protection can be an 80A circuit breaker
d.all of these
Definition
d. all of these
Term
Conductor resistance is determined by ____.

a.material type
b.cross sectional area
c.conductor length
d.all of these
Definition
d. all of these
Term
Conductor cross sectional area is expressed in AWG or ____.

a.square inches
b.mils
c.circular mils
d.none of these
Definition
c. circular mils
Term
The resistance of a conductor is directly proportional to its length.

a.true
b.false
Definition
a. true
Term
_____ currents are small independent currents that are produced as a result of the expanding collapsing magnetic field. They flow erratically within the conductor opposing current flow.

a.lenz
b.ohm's
c.eddy
d.kirchoff's
Definition
c. Eddy
Term
The expanding and collapsing magnetic field induces a counter voltage within the conductors, which repels the flowing electrons toward the conductor surface. This is known as ____ effect.

a.inductive
b.skin
c.surface
d.watt
Definition
b. skin
Term
The opposition to current flow is greater for ac circuits than for dc circuits because of _____.

a.eddy currents
b.skin effect
c.inductive reactance
d.all of these
Definition
d. all of these
Term
What kind of motor tends to run away if not always connected to a load?

a.dc shunt
b.dc series
c.ac synchronous
d.ac series
Definition
b.dc series
Term
What kind of motor tends to run away if not always connected to a load?

a.applied voltage
b.power
c.applied torque
d.motor speed
Definition
a. applied voltage
Term
This type of motor can operate on both AC and DC, and is commonly used in power drills, vacuum cleaners and other household items.

a.ac motor
b.universal motor
c.dc shunt motor
d.wound rotor
Definition
b. universal motor
Term
The rating 1000 ohm, 10 watt is typical for what?

a.resistor
b.heater
c.receptacle
d.thhn wire
Definition
a. resistor
Term
What are the nameplate amperes of a 20hp, 208V motor operating at 88% efficiency with a 90% power factor?

a.50A
b.58A
c.75A
d.80A
Definition
d. 80A
Term
If two parallel conductors are connected at both ends the cross-sectional area becomes ____?

a.larger
b.smaller
c.does not matter
Definition
a. larger
Term
Capacitors are measured in?

a.henrys
b.farads
c.ohms
d.amps
Definition
b. farads
Term
If a coworker is burned by battery acid you should apply ____ to the wound.

a.water for 20 minutes
b.iodine
c.lye and a bandage
Definition
a. water for 20 minutes
Term
The resistance of copper wire is _____ proportional to its length and inversely proportional to its cross sectional area.

a.inversely
b.does not matter
c.directly
d.universally
Definition
c. directly
Term
What is the disadvantage of an autotransformer?

a.the windings are electrically isolated
b.the windings are not electrically isolated
c.loss of voltage
d.loss of current
Definition
b. the windings are not electrically isolated
Term
The most likely cause for current to vary in a circuit is ____? a.loss or poor connection b.change in voltage c.change in current d.insulation deterioration
Definition
a. loss or poor connection
Term
What tool is used to measure specific gravity?

a.metter
b.ammeter
c.hydrometer
d.voltmeter
Definition
c. hydrometer
Term
What type of wrench is not used to tighten rigid metal conduit?

a.strap wrench
b.box wrench
c.chain wrench
d.cooling the joint
Definition
b. box wrench
Term
When soldering conductor joints, what is flux used for?

a.heating the surface
b.joining the conductors
c.cleaning and preparing the surface
d.cooling the joint
Definition
c. cleaning and preparing the surface
Term
When a resistive load is operated at a voltage 10% higher than the nameplate rating of the appliance, the appliance will ___?

a.blow up
b.use more power
c.draw a lower current
d.have a longer life
Definition
b. use more power
Term
When using an ammeter the leads should be connected in ___ with the circuit.

a.parallel
b.series-parallel
c.series
d.parallel-series
Definition
c. series
Term
The greater number of free electrons, the better the _____?

a.ampacity
b.conductivity
c.resistance
d.insulation life
Definition
b. conductivity
Term
A solderless connector ___ for two conductors without the need of any actual soldering.

a.protects the wire
b.establishes a connection
c.cleans the wire
d.heats the wire
Definition
b. establishes a connection
Term
How can conductor voltage drop be reduced?

a.reduce the conductor resistance
b.increase the conductor size
c.decrease the conductor length
d.all of these
Definition
d. all of these
Term
A flickering fluorescent bulb can _____?

a.melt the conductors
b.cause damage to the ballast
c.burn out the bulb
d.give the bulb longer life
Definition
b. cause damage to the ballast
Term
What is the advantage of "S" type fuses?

a.quicker reaction
b.slower burn
c.cheaper cost
d.look prettier
Definition
b. slower burn
Term
The total opposition to current flow in an ac circuit is expressed in ohms and called _____.

a.impedance
b.conductance
c.reluctance
d.resistance
Definition
a. impedance
Term
The part of wiring system past the last overcurrent protection device is called the ____ circuit?

a.branch
b.feeder
c.service
d.neutral
Definition
a. branch
Term
The part of the wiring system prior to the last overcurrent protection device is called the _____ circuit?

a.feeder
b.service
c.branch
d.load
Definition
a. feeder
Term
The frequency of an ___waveform is the number of times a current goes 360 degrees in ____?

a.AC, 60 sec
b.AC, 1 sec
c.DC 60 sec
d.DC 1 sec
Definition
b. AC, 1 sec
Term
When a calculation results in a fraction of an ampere that is less than ____, that fraction is permitted to be dropped.

a.0.40
b.0.45
c.0.50
d.0.55
Definition
c. 0.50
Term
When sizing the feeder or service, each dwelling unit must have a minimum feeder load of ____ for the two small appliances circuits.

a.1000VA
b.2000VA
c.3000VA
d.4000VA
Definition
c. 3,000VA
Term
The NEC requires a minimum of 3 VA for each square foot of living space for the required general lighting and general use receptacles for dwelling units. The dimensions for determining the area are computed from the outside of the building and do not include ____.

a.open porches
b.garages
c.spaces not adaptable for future use
d.all of these
Definition
d. all of these
Term
The 3 VA for each square foot of living space for general lighting includes receptacles rated 20A, but not the small appliance or laundry circuit receptacles.

a.true
b.false
Definition
a. true
Term
The NEC recognizes that the general lighting and receptacles, and small appliance and laundry circuits will not be on or loaded at the same time and permits a(n) ___ to be applied to the total of these loads.

a.demand factor
b.adjustment factor
c.correction factor
d.correction
Definition
a. demand factor
Term
The feeder or service calculated load for electric clothes dryers located in dwelling units must not be less than ____.

a.5,000W
b.the nameplate rating
c.A or B
d.the greater of a or b
Definition
d. the greater of a or b
Term
A feeder or service dryer load is required even if the dwelling unit does not contain an electric dryer.

a.true
b.false
Definition
b. false
Term
In a wye-configured transformer, the line voltage is the same as the phase (winding) voltage.

a.true
b.false
Definition
b. false
Term
What is the general lighting load and general use receptacle load for a 2,100 sq. ft. home that has 74 receptacle outlets and nine recessed luminaires rated at 100W each?

a.2,100va
b.4,200va
c.6,300va
d.8,400va
Definition
c. 6,300va

2,100 x 3 = 6,300va
Term
What is the feeder or service calculated load for a 4kw dryer?

a.3kw
b.4kw
c.5kw
d.6kw
Definition
c. 5kw

dryer load must not be less than 5,000 VA
Term
What is the feeder or service calculated load for a 5.50 kw dryer?

a.3kw
b.4kw
c.5kw
d.5.50kw
Definition
d. 5.50kw

dryer load must not be less than 5,000VA
Term
What is the feeder or service calculated load for an 11.50 kw range?

a.7kw
b.8kw
c.9kw
d.10kw
Definition
b. 8kw

table 220.55 column c
Term
What is the calculated load for a 4.50kw dryer?

a.4.50kw
b.5kw
c.5.50kw
d.8kw
Definition
b. 5kw

dryer must not be less than 5,000kw
Term
How many 15A, 120V branch circuits are required for general use receptacles and lighting in a 1,800 sq.ft. dwelling unit?

a.1
b.2
c.3
d.4
Definition
c. 3

1,800 x 3 = 5,400
5,400 / 120 = 45
45 / 14 = 3
Term
A dwelling unit contains one of each of the following: dishwasher (1/2 hp) and water heater (4kva). What is the appliance calculated load for the dwelling unit?

a.4kva
b.5.10kva
c.9kva
d.11kva
Definition
b. 5.10kva
Term
A dwelling unit contains a 5.50 kw electric clothes dryer. What is the feeder calculated load for the dryer?

a.3.38kw
b.4.50kw
c.5kw
d.5.50kw
Definition
d. 5.50kw

minimum of 5,000kw otherwise use nameplate
Term
The maximum feeder calculated calculated load for an 8kw range is ___.

a.6.30kw
b.8kw
c.8.50kw
d.12kw
Definition
b. 8 kw

table 220.55
Term
Each dwelling unit must have a feeder load consisting of ____ for a 20A laundry circuit.

a.1,500va
b.2,000va
c.3,000va
d.4,500va
Definition
a. 1,500va
Term
A 1,500W resistive heater is rated 230V and is connected to a 208V supply. The power consumed for this load at 208V will be approximately ____.

a.1,225w
b.1,625w
c.1,750w
Definition
a. 1,225w
Term
If a transformer is 97% efficient, for every 1kw input, there will be ____ output.

a.970w
b.1,000w
c.1,030w
d.1,200w
Definition
a. 970w

1,000 x .97 = 970W
Term
If the output power is 1,600w and the equipment is 88% efficient, what are the input amperes at 120V?

a.10A
b.15A
c.20A
d.25A
Definition
b. 15A

16 x .88 = 14.08 -> 15A
Term
Dual voltage ac motors are made with two field windings. The field windings are connected in ____ for low voltage operation and in ____ for high voltage operation.

a.series, parallel
b.parallel, series
c.series, series
d.parallel, parallel
Definition
b. parallel, series
Term
For dual voltage 230/460V motor, the field windings are connected in parallel for ____ operation and in series for ___ operation.

a.230v, 460v
b.460v, 230v
c.230v, 230v
d.460v, 460v
Definition
a. 230v, 460v
Term
Motors are used to convert electrical energy into mechanical work and the output mechanical work of a motor is rated in horsepower. 1hp = ____.

a.476w
b.674w
c.746w
d.840w
Definition
c. 746w
Term
What is the cross sectional area in square inches for 10 THHN?

a.0.0117
b.0.0172
c.0.0211
d.0.0252
Definition
c. 0.0211
ch.9 table 5
Term
How many 6 RHH conductors (without outer cover) can be installed in trade size 1 ¼ electrical nonmetallic tubing?

a.7
b.13
c.16
d.25
Definition
a. 7
table c.2
Term
Which of the following statements about a 30hp, 460V, three phase synchronous motor and a 10hp, 460V, three phase motor are true?

a.the 30 hp motor is supplied by 8awg conductors with an 80a breaker
b.the 10 hp motor is supplied by 14awg conductors with a 35A breaker
c.the feeder conductors must be 6awg conductors with a 90A breaker
d.all of these
Definition
d. all of these
Term
An existing trade size ¾ rigid metal conduit nipple contains four 10 THHN conductors and one 10 AWG (bare stranded) ground wire. How many additional 10 THHN conductors can be installed?

a.5
b.7
c.9
d.11
Definition
d. 11
Term
Where a circuit supplies continuous loads or any combination of continuous and noncontinuous loads, the rating of the overcurrent device must not be less than the noncontinuous load plus ____ of the continuous load.

a.80%
b.100%
c.125%
d.150%
Definition
c. 125%
Term
How many 10awg conductors are permitted in a 4 x 1 ½ square box?

a.8
b.9
c.10
d.11
Definition
a.8
Term
A continuous load of 27A requires the circuit overcurrent device to be sized at ____.

a.20A
b.30A
c.35A
d.40A
Definition
c.35A
Term
What size overcurrent device is required for a 45A continuous load? The circuit is in a raceway with 14 current carrying conductors.

a.45A
b.50A
c.60A
d.70A
Definition
c. 60A
Term
A 65A continuous load requires a ____ overcurrent protection device.

a.60A
b.70A
c.75A
d.90A
Definition
d. 90A
Term
Motors with a nameplate temperature rise rating not over 40 c must have the overload protection device sized at no more than ____ percent of the motor nameplate rating.

a.100
b.115
c.125
d.135
Definition
c. 125
Term
Motors with a nameplate service factor of 1.15 or more must have an overload protection device sized at no more than ____ percent of the motor nameplate current rating.

a.100
b.115
c.125
d.135
Definition
c. 125
Term
Motors that have a service factor rating of 1.10 must have the overload protection device sized at not more than ___ percent of the motor nameplate ampere rating.

a.100
b.115
c.125
d.135
Definition
b. 115
Term
If dual-element fuse is used for overload protection, what size fuse is required for a 30hp, 460V, three phase synchronous motor, with a temperature rise of 39 C?

a.20A
b.25A
c.30A
d.40A
Definition
d. 40A
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