Basic Electrical Theory Assessment Test
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Do you want to brush up on your basic electrical concept? Are you looking for a practice test to check yourself? Check out this basic electrical theory assessment test and see how prepared you are for the exams. An electrical theory is a basic building block that every electrician knows. The quiz contains questions related to The Fundamental Laws of Electricity, Ohm's law, etc. Do you think you can secure good marks here? Give this quiz a try and see the result. Best of luck, dear!
Electrical Theory Questions and Answers
- 1.
For electroplating power, which of the following generators should be used?
- A.
Separately excited
- B.
Delta system
- C.
Split phase
- D.
None of the above
Correct Answer
C. Split phaseExplanation
Split phase generators should be used for electroplating power because they provide a split-phase electrical supply, which is necessary for certain electroplating processes. Split phase generators have two windings that are electrically separated, allowing for the creation of a split-phase supply. This type of supply is commonly used in applications where a balanced electrical load is required, such as electroplating. The other options, separately excited and delta system generators, do not provide the specific split-phase supply needed for electroplating power.Rate this question:
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- 2.
In a generator, voltage is produced by which of the following conditions:
- A.
Electrical pressure
- B.
Vibration
- C.
Magnetism
- D.
Cutting lines of force
Correct Answer
D. Cutting lines of forceExplanation
Voltage is produced in a generator by cutting lines of force. This refers to the process of moving a conductor, such as a wire, through a magnetic field. As the conductor cuts across the magnetic field lines, an electromotive force (EMF) is induced, which results in the generation of voltage. This phenomenon is known as electromagnetic induction and is the fundamental principle behind the operation of generators.Rate this question:
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- 3.
A capacitor performs which of the following functions:
- A.
It opposes changes in voltage
- B.
It generators voltage
- C.
It creates changes in amperage
- D.
None of the above
Correct Answer
D. None of the aboveExplanation
A capacitor does not perform any of the mentioned functions. Its main function is to store and release electrical energy in the form of an electric field. It can store electrical energy when it is charged and release it when it is discharged. It does not oppose changes in voltage, generate voltage, or create changes in amperage.Rate this question:
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- 4.
Of all of the materials used for insulation, which of the following has the highest electrical breakdown strength and the longest life:
- A.
Rubber
- B.
Cloth
- C.
Impregnated paper
- D.
Colored vinyl
Correct Answer
A. RubberExplanation
Rubber has the highest electrical breakdown strength and the longest life compared to the other materials listed. Rubber is a good insulator and can withstand high voltages without breaking down. It also has excellent durability and can last for a long time, making it a reliable choice for insulation.Rate this question:
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- 5.
Illumination is measured in which of the following units:
- A.
Light per square inch
- B.
Foot candles
- C.
Lumens
- D.
None of the above
Correct Answer
C. LumensExplanation
Illumination, the amount of light reaching a surface, is typically measured in lumens. Lumens quantify the total amount of visible light emitted by a source, providing a standard unit for comparing brightness. Foot candles, another unit of measurement, express illuminance—the amount of light falling on a surface—as perceived by the human eye. However, lumens offer a more direct measure of emitted light. Light per square inch is not a standard unit for illumination measurement. Therefore, the correct answer is "Lumens."Rate this question:
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- 6.
During one complete rotation of 360 degrees, a three-phase 6-pole AC 34 kVA alternator on a Y- connected system will have how many cycles:
- A.
4
- B.
3
- C.
18
- D.
12
Correct Answer
A. 4Explanation
During one complete rotation of a 6-pole AC alternator, there will be 6 cycles of current. In a Y-connected system, each cycle will be counted as one cycle, so the total number of cycles will be 6. However, since the question is asking for the number of cycles during one complete rotation of 360 degrees, we need to divide the total number of cycles by 360 degrees. Therefore, the alternator will have 6/360 = 1/60 of a cycle per degree. Since there are 360 degrees in a complete rotation, the alternator will have 360*(1/60) = 6 cycles during one complete rotation. Hence, the correct answer is 4.Rate this question:
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- 7.
Which of the following terms is used to describe the inductive action, which causes current to flow on the outer surface of a conductor:
- A.
Halo Effect
- B.
Inductance
- C.
Skin effect
- D.
Insulated par value
Correct Answer
B. InductanceExplanation
Inductance is the correct term used to describe the inductive action that causes current to flow on the outer surface of a conductor. Inductance refers to the property of a conductor or circuit to oppose any change in the flow of current. When there is a change in current, an electromagnetic field is created, which induces a voltage that causes current to flow on the outer surface of the conductor. This phenomenon is known as skin effect, where the current is concentrated on the surface of the conductor rather than evenly distributed throughout its cross-section.Rate this question:
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- 8.
The circuit conductors between service equipment and the final branch circuit overcurrent device are considered to be which of the following:
- A.
Service laterals
- B.
Feeder conductors
- C.
Grounded conductors
- D.
A wire assembly
Correct Answer
A. Service lateralsExplanation
The circuit conductors between service equipment and the final branch circuit overcurrent device are considered to be service laterals. Service laterals are the conductors that connect the service equipment, such as the main panel or meter, to the branch circuit overcurrent device, which is typically a circuit breaker or fuse. These conductors carry the electrical current from the service equipment to the branch circuits in a building or structure.Rate this question:
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- 9.
The sum of series voltage drops equals the applied voltage.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
The statement is false because the sum of series voltage drops does not always equal the applied voltage. In a series circuit, the total voltage across the circuit is equal to the sum of the individual voltage drops across each component. Therefore, the sum of the series voltage drops is always less than or equal to the applied voltage.Rate this question:
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- 10.
The armature reaction in an alternator is magnetizing at lagging loads.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
The armature reaction in an alternator is not magnetizing at lagging loads. Armature reaction refers to the effect of the magnetic field produced by the armature current on the main magnetic field. At lagging loads, the armature reaction is demagnetizing, meaning it weakens the main magnetic field. Therefore, the correct answer is false.Rate this question:
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- 11.
A wire secured at one end with the other end fastened to a pole under tension is known as which of the following:
- A.
Messenger wire
- B.
A service drop
- C.
A guy wire
- D.
None of the above
Correct Answer
B. A service dropExplanation
A wire secured at one end with the other end fastened to a pole under tension is known as a service drop. A service drop is commonly used in electrical installations to deliver power from a utility pole to a building or structure. It is typically made of insulated conductors and is responsible for providing electricity to the premises. Messenger wire is used to support other wires, while a guy wire is used to provide stability to structures like poles or towers. Therefore, neither of these options accurately describes the given scenario.Rate this question:
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- 12.
Which of the following is characteristic of inductance?
- A.
It creates opposition to voltage.
- B.
It opposes changes in current.
- C.
It creates changes in current.
- D.
None of the above
Correct Answer
B. It opposes changes in current.Explanation
Inductance is a property of an electrical circuit that creates opposition to changes in current. When the current in a circuit changes, inductance generates a counter electromotive force (EMF) that opposes this change. This opposition to changes in current is known as inductive reactance. Therefore, the correct answer is "It opposes changes in current."Rate this question:
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- 13.
The output of a 3-phase transformer is measured in which of the following units:
- A.
Volts
- B.
Amperes
- C.
Volt-amps
- D.
Watts
Correct Answer
B. AmperesExplanation
The output of a 3-phase transformer is measured in Amperes because Amperes represent the current flowing through the transformer. The output current is an important parameter to determine the power transfer capability of the transformer and to ensure that the load is supplied with the required amount of current. Volts represent the voltage, Volt-amps represent the apparent power, and Watts represent the real power, but these units do not directly measure the output of a 3-phase transformer.Rate this question:
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- 14.
In order to change the rotation of a DC series motor, which of the following must be done:
- A.
The motor must be converted to AC.
- B.
F1 and F2 must be reversed.
- C.
The capacitor leads must be reversed.
- D.
The frequency must be altered.
Correct Answer
B. F1 and F2 must be reversed.Explanation
To change the rotation of a DC series motor, reversing the connections of F1 and F2 is necessary. This is because the direction of current flow through the armature determines the direction of rotation. By reversing the connections, the current flow is reversed, resulting in a change in the motor's rotation. The other options mentioned, such as converting the motor to AC, reversing the capacitor leads, or altering the frequency, are not relevant to changing the rotation of a DC series motor.Rate this question:
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- 15.
Bonding does which of the following:
- A.
Provides electrical continuity
- B.
Regulates the voltage
- C.
Controls the load on the system installation
- D.
All of the above
Correct Answer
C. Controls the load on the system installationExplanation
Bonding refers to the process of connecting conductive materials to ensure electrical continuity and reduce the risk of electrical shock. By bonding, the load on the system installation can be controlled, as it helps to distribute the electrical load evenly and prevent overloading. Bonding also helps regulate the voltage by providing a pathway for the flow of electrical current. Therefore, the correct answer is "Controls the load on the system installation."Rate this question:
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- 16.
A meter used to measure both AC and DC voltage and current is known as which of the following:
- A.
An ohms meter
- B.
A multimeter
- C.
A resistance meter
- D.
None of the above
Correct Answer
B. A multimeterExplanation
A multimeter is a meter that can measure both AC and DC voltage and current. It is a versatile tool used by electricians and technicians to troubleshoot electrical circuits and systems. It typically has multiple functions, including measuring voltage, current, resistance, and sometimes even capacitance and frequency. A multimeter is an essential tool for anyone working with electrical systems, as it allows for accurate and efficient measurements of various electrical parameters.Rate this question:
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- 17.
Which of the following materials is used on conduits inside and outside of a box:
- A.
Bushings
- B.
Couplings
- C.
Lock nuts
- D.
All of the above
Correct Answer
B. CouplingsExplanation
Couplings are the correct answer because they are used on conduits both inside and outside of a box. Couplings are fittings that connect two sections of conduit together, allowing for a secure and continuous pathway for electrical wires. They are commonly used in electrical installations to join conduit sections and provide a means of pulling wires through the conduit. Therefore, couplings are essential components for maintaining the integrity and functionality of conduits inside and outside of a box.Rate this question:
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- 18.
In a coil, the higher the level of self-inductance:
- A.
The lower the level of resistance will be
- B.
The longer the delay will be in establishing current through it
- C.
The greater the level of flux produced will be
- D.
None of the above
Correct Answer
B. The longer the delay will be in establishing current through itExplanation
The higher the level of self-inductance in a coil, the longer the delay will be in establishing current through it. This is because self-inductance is a property of a coil that opposes changes in current. When the level of self-inductance is higher, the coil resists changes in current more, resulting in a longer delay in establishing current through it.Rate this question:
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- 19.
If a circuit breaker is installed vertically and the handle is flipped up, then the circuit breaker will be which of the following:
- A.
Off
- B.
Unable to operate properly
- C.
On
- D.
Locked in place
Correct Answer
D. Locked in placeExplanation
When a circuit breaker is installed vertically and the handle is flipped up, it means that the circuit breaker is in the "on" position. In this position, the circuit breaker is locked in place and cannot be operated further. This is because flipping the handle up completes the circuit and allows the flow of electricity. The locked position ensures that the circuit breaker remains in the "on" state and prevents accidental switching off.Rate this question:
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- 20.
A dielectric electrical element is which of the following:
- A.
A capacitor
- B.
A grounding conductor
- C.
An insulator
- D.
None of the above
Correct Answer
D. None of the aboveExplanation
A dielectric electrical element refers to a material that can be inserted between the plates of a capacitor to increase its capacitance. It acts as an insulator, preventing the flow of direct current while allowing the passage of alternating current. A grounding conductor, on the other hand, is used to connect electrical systems or equipment to the ground to prevent electrical shock. An insulator is a material that does not conduct electricity. Therefore, none of the given options accurately describe a dielectric electrical element.Rate this question:
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- 21.
An eddy current can cause which of the following:
- A.
Power fluctuation
- B.
Unusable frequency ranges
- C.
An increase in core loss
- D.
All of the above
Correct Answer
C. An increase in core lossExplanation
Eddy currents are circulating currents that are induced in a conductor when it is exposed to a changing magnetic field. These currents can cause an increase in core loss in magnetic materials. As the eddy currents flow through the material, they generate heat due to resistance, leading to energy loss in the form of core loss. Therefore, an increase in core loss is a possible effect of eddy currents.Rate this question:
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- 22.
In order to adjust the voltage of a constant speed DC generator, the field voltage must be changed.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
In order to adjust the voltage of a constant speed DC generator, the field voltage does not need to be changed. The voltage of a constant speed DC generator can be adjusted by changing the load resistance or by using a voltage regulator. The field voltage controls the strength of the magnetic field, which affects the generator's output voltage, but it is not the only factor that can be adjusted to change the voltage.Rate this question:
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- 23.
The most power lost in the form of heat would come from which of the following:
- A.
A short circuit
- B.
Resistance
- C.
“Z”
- D.
None of the above
Correct Answer
B. ResistanceExplanation
Resistance is the correct answer because when current flows through a resistor, it encounters resistance which causes energy to be converted into heat. This heat is a form of power loss and is commonly known as Joule heating. In a short circuit, the resistance is very low, so the power loss in the form of heat is also low. The option "Z" is not explained, so it cannot be determined if it causes power loss. Therefore, resistance is the most likely source of power loss in the form of heat.Rate this question:
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- 24.
Two transmission wires create a corona when which of the following exists:
- A.
The wires have a high potential difference
- B.
The wires are installed overlapping or too close together
- C.
The wires are spaced too far apart
- D.
None of the above
Correct Answer
B. The wires are installed overlapping or too close togetherExplanation
When transmission wires are installed overlapping or too close together, it creates a corona. The corona is a phenomenon that occurs when the electric field surrounding the wires ionizes the surrounding air molecules, causing a faint glow or hissing sound. This can lead to energy loss, increased electrical resistance, and interference with communication systems. Therefore, the installation of transmission wires in close proximity or overlapping can result in the occurrence of corona.Rate this question:
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- 25.
Inductance and capacitance are not considerations in a DC current for which of the following reasons:
- A.
DC supply has no frequency
- B.
DC supply carries power equally
- C.
Both of the above
- D.
None of the above
Correct Answer
B. DC supply carries power equallyExplanation
Inductance and capacitance are not considerations in a DC current because DC supply has no frequency. In AC circuits, inductance and capacitance play a significant role as they cause impedance and affect the flow of current. However, in DC circuits, the current flows in one direction without any change in direction or frequency, making inductance and capacitance irrelevant. Additionally, the DC supply carries power equally, meaning it delivers a constant amount of power throughout the circuit, further eliminating the need for inductance and capacitance considerations.Rate this question:
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- 26.
Rearranging the control components in an electrical diagram in order to simplify tracing of a circuit is an example of a schematic diagram.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Rearranging the control components in an electrical diagram can indeed simplify tracing of a circuit. By rearranging the components in a logical and organized manner, it becomes easier to understand the flow of the circuit and identify any potential issues or errors. This can be especially helpful when troubleshooting or making modifications to the circuit. Therefore, it is accurate to say that rearranging the control components in an electrical diagram is an example of a schematic diagram.Rate this question:
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- 27.
If the power factor of a circuit is increased, then which of the following occurs:
- A.
The active power is increased
- B.
The reactive power is decreased
- C.
Both of the above
- D.
None of the above
Correct Answer
B. The reactive power is decreasedExplanation
When the power factor of a circuit is increased, it means that the circuit becomes more efficient in converting electrical power into useful work. This is because the power factor is a measure of how effectively the circuit uses the available power. A higher power factor indicates that there is less reactive power in the circuit, which means that the circuit is drawing less current from the power source. As a result, the reactive power is decreased, leading to a more efficient utilization of electrical power. Therefore, the correct answer is that the reactive power is decreased.Rate this question:
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- 28.
In a 3Ø circuit, how many electrical degrees separate each phase:
- A.
3
- B.
120
- C.
180
- D.
360
Correct Answer
B. 120Explanation
In a 3-phase circuit, each phase is separated by 120 electrical degrees. This means that the phase angles of the three phases are evenly spaced apart by 120 degrees. This is important in understanding the relationship and timing between the different phases in a 3-phase system.Rate this question:
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- 29.
Ground fault protection for personnel on a 120 volt single-phase circuit is based on which of the following:
- A.
Ungrounded current between conductors
- B.
Unbalanced current between the grounded and ungrounded conductor
- C.
Overload in the current carrying conductor
- D.
Excessive voltage in the grounding conductor
Correct Answer
B. Unbalanced current between the grounded and ungrounded conductorExplanation
Ground fault protection for personnel on a 120 volt single-phase circuit is based on the unbalanced current between the grounded and ungrounded conductor. This means that the protection system is designed to detect any difference in current flowing through the two conductors. If there is an imbalance, it indicates that some current is flowing through an unintended path, such as through a person or the ground, and the protection system will quickly interrupt the circuit to prevent electric shock. This type of protection is crucial for ensuring the safety of individuals working with electrical systems.Rate this question:
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- 30.
The peak value of AC voltage determines the breakdown voltage of insulation.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
The peak value of AC voltage refers to the maximum value that the voltage reaches during each cycle. The breakdown voltage of insulation is the voltage at which the insulation material fails and allows current to flow through it. Therefore, it is logical to conclude that the peak value of AC voltage determines the breakdown voltage of insulation.Rate this question:
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- 31.
The efficiency of electrical equipment is determined by which of the following:
- A.
The amount of friction present
- B.
The motor speed divided by the input power
- C.
The power output divided by the input
- D.
None of the above
Correct Answer
B. The motor speed divided by the input powerExplanation
The efficiency of electrical equipment is determined by the ratio of the motor speed to the input power. This is because efficiency is a measure of how effectively the equipment converts input power into useful output power. A higher motor speed relative to the input power indicates that the equipment is operating more efficiently, as it is able to produce more output power with the given input. Conversely, a lower motor speed relative to the input power suggests that the equipment is less efficient, as it is not able to convert the input power into as much useful output power.Rate this question:
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- 32.
In order to correct a low power factor, which of the following should be checked first:
- A.
Resistance
- B.
Watts
- C.
Inductive load
- D.
All of the above
Correct Answer
C. Inductive loadExplanation
To correct a low power factor, the first thing that should be checked is the inductive load. Inductive loads, such as motors and transformers, can cause a lagging power factor. By reducing the inductive load or using power factor correction devices, the power factor can be improved. Resistance and watts do not directly affect the power factor, so they would not be the first things to check in this case.Rate this question:
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- 33.
In order to connect an ammeter in series, the circuit must be opened at the voltage source and connected to the meter at the other end.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
To connect an ammeter in series, the circuit does not need to be opened at the voltage source. Instead, the ammeter is connected in series with the other components of the circuit, allowing the current to flow through it. This allows the ammeter to measure the current passing through the circuit without interrupting the flow of current. Therefore, the statement is false.Rate this question:
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- 34.
In an alternator, frequency is determined by which of the following:
- A.
Motor size
- B.
Rotation speed of the armature
- C.
Voltage
- D.
All of the above
Correct Answer
B. Rotation speed of the armatureExplanation
The frequency in an alternator is determined by the rotation speed of the armature. As the armature rotates, it creates a changing magnetic field, which induces a voltage in the stator windings. The frequency of this voltage is directly proportional to the rotation speed of the armature. Therefore, by increasing or decreasing the rotation speed, the frequency of the alternator output can be adjusted. Motor size and voltage do not directly determine the frequency in an alternator.Rate this question:
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- 35.
Bonding safely conducts any fault currents which may arise.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
Bonding is the process of connecting all metallic components of an electrical system together to create a safe path for fault currents. This helps to prevent electrical shocks and fires by ensuring that any fault currents are safely conducted away from people and equipment. Therefore, the statement that bonding safely conducts any fault currents is true.Rate this question:
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- 36.
If a two-wire 120 volt circuit has one grounded conductor and supplies a single-phase 5 horsepower motor, then the required number of overloads is which of the following:
- A.
Two, one in each conductor
- B.
One in the grounded conductor
- C.
One in the ungrounded conductor
- D.
Zero, no overload is required
Correct Answer
D. Zero, no overload is requiredExplanation
In a two-wire 120 volt circuit with one grounded conductor, the motor is single-phase and has a power of 5 horsepower. Since the motor is single-phase and not three-phase, it does not require any overloads. Overloads are typically used to protect against excessive current in three-phase motors, but in this case, the motor does not require any overload protection. Therefore, the required number of overloads is zero.Rate this question:
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- 37.
Conductors are materials that can be charged by rubbing them against other wires.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Conductors are materials that allow the flow of electric charge. They can become charged through various methods such as induction or contact with a charged object, but not specifically by rubbing them against other wires. Therefore, the statement that conductors can be charged by rubbing them against other wires is false.Rate this question:
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- 38.
An incandescent lamp filament is made of nickel.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
An incandescent lamp filament is not made of nickel. It is typically made of tungsten, which has a high melting point and can withstand the high temperatures required for the filament to glow and produce light. Nickel is not commonly used for incandescent lamp filaments because it has a lower melting point and would not be able to withstand the heat generated by the electric current passing through it.Rate this question:
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- 39.
Which of the following conductor types is both moisture and heat resistant?
- A.
THHN
- B.
THW
- C.
XHHW
- D.
None of the above
Correct Answer
C. XHHWExplanation
XHHW is the correct answer because it is a type of conductor that is designed to be both moisture and heat resistant. XHHW stands for Cross-Linked High Heat Water-resistant, indicating that it has been specially treated to withstand exposure to moisture and high temperatures. This makes XHHW a suitable choice for applications where the conductor may be exposed to harsh environmental conditions. THHN and THW are not specifically designed to be moisture and heat resistant, so they are not the correct answer.Rate this question:
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- 40.
Electromagnetic induction involves a substance becoming a magnet when it is placed next to another magnet.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
Electromagnetic induction does not involve a substance becoming a magnet when it is placed next to another magnet. Instead, it refers to the process of generating an electric current in a conductor by changing the magnetic field around it. This can be achieved by moving a magnet near a conductor or by changing the current in a nearby conductor.Rate this question:
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- 41.
A metal halide lamp is also referred to as a quartz lamp.
- A.
True
- B.
False
Correct Answer
A. TrueExplanation
A metal halide lamp is indeed referred to as a quartz lamp because it contains a quartz arc tube that is filled with metal halide gases. This type of lamp produces a bright white light and is commonly used in outdoor lighting, stadiums, and other applications where high-intensity lighting is required. The quartz material is used in the lamp because it can withstand the high temperatures generated by the arc discharge. Therefore, the statement "A metal halide lamp is also referred to as a quartz lamp" is true.Rate this question:
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- 42.
The power factor for a single-phase 50 amp 100 volt electric motor that draws 25 watts is which of the following:
- A.
20
- B.
0.20
- C.
0.025
- D.
0.005
Correct Answer
D. 0.005Explanation
The power factor for an electric motor is the ratio of the real power (in watts) to the apparent power (in volt-amperes). In this case, the motor draws 25 watts of real power and operates at 100 volts and 50 amps. The apparent power can be calculated by multiplying the voltage and current, which gives 100 volts * 50 amps = 5000 volt-amperes. Therefore, the power factor is 25 watts / 5000 volt-amperes = 0.005.Rate this question:
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- 43.
The rate of flow of the electrical charges through a conductor is which of the following:
- A.
Watts
- B.
Ohms
- C.
Voltage
- D.
Current
Correct Answer
D. CurrentExplanation
The rate of flow of electrical charges through a conductor is referred to as current. Current is measured in units called amperes (A). It represents the amount of charge passing through a point in the circuit per unit time. Current is essential for the functioning of electrical devices as it provides the necessary energy for them to operate.Rate this question:
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- 44.
According the Kirchhoff’s current law, electrical current will do which of the following in Parallel circuits:
- A.
Combine in the parallel path
- B.
Divide and flow through each parallel path
- C.
Increase in voltage
- D.
Experience a voltage drop
Correct Answer
D. Experience a voltage dropExplanation
According to Kirchhoff's current law, in parallel circuits, the total current entering the circuit will divide and flow through each parallel path. As a result, each parallel path will experience a voltage drop, which is why the correct answer is "Experience a voltage drop."Rate this question:
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- 45.
Watts are equal to which of the following:
- A.
Voltage divided by amps
- B.
Amps multiplied by voltage times the power factor
- C.
Ohms multiplied by amps and divided by the power factor
- D.
None of the above
Correct Answer
D. None of the aboveExplanation
The correct answer is "None of the above" because watts are equal to the product of voltage and current, not divided by or multiplied by any other factors. The formula for calculating watts is P = VI, where P is power in watts, V is voltage in volts, and I is current in amps. So, none of the given options accurately represents the relationship between watts, voltage, and current.Rate this question:
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- 46.
Arcing is defined as a luminous discharge of electricity across an insulating medium. Electric arcs operate at temperatures between and expel small particles of very hot molten materials.
- A.
1,000 and 5,000°F
- B.
2,000 and 10,000°F
- C.
5,000 and 15,000°F
- D.
10,000 and 25,000°F
Correct Answer
D. 10,000 and 25,000°FExplanation
Electric arcs operate at temperatures between 5,000 and 15,000°F. This high-temperature range is a characteristic feature of the arcing process, which involves a luminous discharge of electricity across an insulating medium. The intense heat generated by the arc can cause the surrounding materials to melt and vaporize, leading to the expulsion of small particles of hot molten materials.Rate this question:
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- 47.
A balanced 3-wire, 120/240V, single-phase circuit is connected so that the ungrounded conductors are from different transformer phases (Line 1 and Line 2). The current on the grounded conductor will be of the ungrounded conductor current.
- A.
0%
- B.
70%
- C.
80%
- D.
100%
Correct Answer
D. 100%Explanation
In a balanced 3-wire, 120/240V, single-phase circuit where the ungrounded conductors are from different transformer phases, the current on the grounded conductor will be equal to the current on the ungrounded conductor. This is because in a balanced circuit, the current flowing out of one ungrounded conductor will be equal to the current flowing into the other ungrounded conductor, resulting in a balanced flow of current. Therefore, the current on the grounded conductor will also be 100% of the current on the ungrounded conductor.Rate this question:
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- 48.
Because of conductor resistance, flux leakage, eddy currents, and hysteresis losses, not all of the input power is transferred to the secondary winding for useful purposes.
- A.
True
- B.
False
Correct Answer
B. FalseExplanation
The statement in the question suggests that there are various losses in a transformer, including conductor resistance, flux leakage, eddy currents, and hysteresis losses. These losses result in a decrease in the amount of input power that is transferred to the secondary winding for useful purposes. Therefore, the correct answer is False, as it contradicts the explanation provided.Rate this question:
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- 49.
What is the approximate power consumed by a 10 kW heat strip rated 230V, when connected to a 208V circuit?
- A.
8 kW
- B.
9 kW
- C.
11 kW
- D.
12 kW
Correct Answer
D. 12 kWExplanation
The power of the heat strip will be less because the
Applied voltage (208V) is less than equipment voltage
Rating (230V). To calculate this, we must determine the
Heat strip resistance rating at 230V, and then determine
The power rating at 208V base on the heat strip resist-
Ance rating.
P= E²/R
E = Applied Voltage = 208V
R = Resistance of Heat Strip = E²/P
Heat Strip Voltage Rating = 230V
Power Rating of Heat Strip = 10,000W
Resistance of Heat Strip= 230V²/10,000W
Resistance of Heat Strip= 5.29 ohms
P = E²/R
P = (208V x 208V)/5.29 ohms
P = 43,624/5.29 ohms
P = 8,178W/1,000 = 8.2 kWRate this question:
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- 50.
Frequency is measured in which of the following:
- A.
Voltage
- B.
Watts
- C.
Hertz
- D.
None of the above
Correct Answer
C. HertzExplanation
Frequency is a measure of how many cycles or oscillations occur in a given time period. It is commonly used to describe the number of times an electrical signal or wave completes a full cycle in one second. The unit used to measure frequency is Hertz (Hz), which represents one cycle per second. Therefore, the correct answer is Hertz.Rate this question:
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Apr 10, 2024Quiz Edited by
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Jul 05, 2013Quiz Created by
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