General
General
SITOR-ARQ is a common mode of data communications in the maritime service. It is a system based on transmission bursts and acknowledgements. What is the baud, and interval between the burst transmissions:
SITOR-ARQ is a common mode of data communications in the maritime service. It is a system based on transmission bursts and acknowledgements. What is the baud, and interval between the burst transmissions:
100 baud, 240 ms interval
For info, see Wavecome site's article on WAVECOM Decoder Online Help 10.2.0 SITOR-ARQ
For data burst calculation, please see CCIR 476-4 / CCIR 625 Mode A (aka SITOR ARQ / AMTOR)
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Weather information is commonly sent by radio in map form by one-way facsimile transmission. Two common parameters which must be set by the receiving station are:
Weather information is commonly sent by radio in map form by one-way facsimile transmission. Two common parameters which must be set by the receiving station are:
Index of cooperation (IOC), and revolutions per minute (RPM)
For radiofax, in radio waves SSB mode, sends by radio weather map pictures and information. To translate the radio waves into pictures, in terms of the number of lines, characters per line between the sending machine and the receiving printer, the numerical data was transmitted, known as the index of cooperation (IOC) must known.
Since the radio fax machines used drum readers, the revolutions per minute (RPM) had to be know.
For more info, please see Wikipedia's article on Radiofax.
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2182 kHz is the international radiotelephone distress frequency. It is also used for a calling channel. The authorized mode of emission is H3E (single-sideband full carrier). A3E (double-sideband full carrier) is only authorized for equipment:
2182 kHz is the international radiotelephone distress frequency. It is also used for a calling channel. The authorized mode of emission is H3E (single-sideband full carrier). A3E (double-sideband full carrier) is only authorized for equipment:
Solely intended for distress and safety communications
2182 kHz is Medium Frequency (MF) equivalent of VHF Channel 16. Frequencies in this range typically provide longer range communications.
Code of Federal Regulations, Title 47 Chapter I Subchapter D Part 80 Subpart H Radiotelephony
§ 80.369 Distress, urgency, safety, call and reply frequencies.
47 CFR 80.369(a) In the 1605-3500 kHz band, the frequency 2182 kHz is an international radiotelephony distress, urgency and safety frequency for ship stations, public and private coast stations, and survival craft stations.
It is also used for call and reply by ship stations on a primary basis and by public coast stations on a secondary basis.
The carrier frequency 2191 kHz may be used as a supplementary calling frequency in areas of heavy usage of 2182 kHz .
All stations must use J3E emission when operating on 2182 kHz and 2191 kHz, except that:
47 CFR 80.369(a)(1) H3E emission may be used on 2182 kHz for communications with foreign coast and ship stations; or,
47 CFR 80.369(a)(2) A3E emission may be used on 2182 kHz by portable survival craft stations, or transmitters authorized for use prior to January 1, 1972.
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Ship's power is generated as 3-phase and is ungrounded. On a delta-wound transformer with 120 VAC line-to-line secondary, what is the voltmeter reading from line to ground:
Ship's power is generated as 3-phase and is ungrounded. On a delta-wound transformer with 120 VAC line-to-line secondary, what is the voltmeter reading from line to ground:
Any of the above
Approx 67 volts for a normal balanced system with no faults
VAC for a system with that phase faulted to ground
120 VAC when another phase is faulted to ground
The 3-phase current has three sine waves. The currents are at different angles, with L1 at +120 degrees, L2 at 0 degrees, and L3 at -120 degrees. This is needed to power large electric motors.
When you measure voltage between L2 and either L1 or L3, you will get 120 VAC (volt alternating current).
If there is a short (fault) or an abnormal sine wave combination, resulting from a sine wave current coming in contact with ground.
When 3 sine waves work symmetrically, in a coordinated sequence, then they are balanced. When not experiencing a short (or ground connection), then volt measurement reflects the difference between volt levels (voltage is an expression of the difference of electron pressure between two connections)
The Delta configuration uses 3 wires for the 3 sine waves, with no 4th wire, which would have been the neutral ground wire.
For info on electric phase power generation and distribution, please see Wikipedia's article on Three-phase electric power
For info on electric short circuit faults, please see Wikipedia's article on Electrical fault
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When passing through areas of static charge, high voltages can accumulate on antennas which are insulated from ground. What protects a connected receiver from damage?
When passing through areas of static charge, high voltages can accumulate on antennas which are insulated from ground. What protects a connected receiver from damage?
Any combination of the above
Static charge occurs when there is a difference between negative and positive number of electrons. Electrons flow from negative (toward) to positive (back) connections.
If the flow is interfered with or stopped, then an accumulation of the negative electrons occurs, which is the static electricity (static=> not moving). Thus, electrons can accumulate on antennas, and discharge on the radio receivers.
To prevent sudden electron transfer, like a short spark when you touch something that was rubbed appropriately, items that can absorb the sudden release of electrons protect the radio receiver.
Capacitive coupling is a capacitor that would absorb the release of stored electrons. Diodes control the flow of electrons.
For more info, please see Wikipedia's article on Static Electricity.
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Vertical shipboard antennas for use in the MF band (410-525 kHz) are often fitted with top-hat loading sections. What is the purpose of these structures?
Vertical shipboard antennas for use in the MF band (410-525 kHz) are often fitted with top-hat loading sections. What is the purpose of these structures?
Permits a physically short antenna to appear electrically longer
The top-hat or T-antenna, is a horizontal wire (akin to the Beverage antenna), suspended between to poles, with a third wire connected at the center of the horizontal wire and connected to the transmitter/receiver, kind of like the dipole antenna.
The receiving waves flow from the horizontal wire to the vertical center wire to the receiver. Transmissions flow from the center wire to the both sides of the horizontal wire.
A vertical wire is connected to the center of the horizontal wires and hangs down close to the ground, connected to the transmitter or receiver.
Combined, the two sections form a ‘T’ shape, hence the name. The transmitter power is applied, or the receiver is connected, between the bottom of the vertical wire and a ground connection.
T-antenna is easily installed ships between masts and vertical center line connected to the trans/receiver. (Even Titanic used this configuration and sended out the distress signal.)
To extend the wavelength of a shorter antenna, it should be mounted as high as possible, as mathematically its height is squared for effective receiving or transmitting.
For more info, please see Wikipedia's article on T-Antenna.
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Modern reserve transmitters are solid-state designs and transmit using only A2 modulation. When measuring transmitter center frequency, what precaution must be taken:
Modern reserve transmitters are solid-state designs and transmit using only A2 modulation. When measuring transmitter center frequency, what precaution must be taken:
Modulation must be reduced to zero to eliminate sidebands
This modulation can be thought of as the Double Sideband Suppressed Carrier Modulation (DSBSC). Thus, data is sent by modulating the carrier frequency itself. The AM radio can easily pick up these continuous wave propagations.
Because all of the transmitted power (volts x amperes=watts), is concentrated on the carrier frequency, without being dispersed on upper or lower sidebands. Thus, it can carry the signal much farther.
For more info, please see Wikipedia's article on Types of radio emissions and Continuous wave
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Voltage may be expressed by what other expression?
Voltage may be expressed by what other expression?
All of the above
Because the difference in the number of electrons between two items, when they are connected there is a waterfall like flow of electrons. The amount of rushing electrons to the low electrons area is called the volt amount.
It can be thought of as the pressure of the flow of electrons due to the difference in potential (amount of electrons).
If you multiply the amount of electrons, or the current (ampers) by the amount of resistance that a medium through which electrons flow (silver, copper, not glass), then you will get the amount of voltage (pressure on the amount of electrons to move).
Voltage as IF drop may refer to the (I) as symbol for current (ampers) and (F) as factor or force. More on Voltage drop on Wikipedia's article Voltage drop
For Voltage info, see Electrical 4 U site article What is Voltage? and Wikipedia's article Voltage
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Amperage may also be known by:
Amperage may also be known by:
All of the above
In simplest terms, it is the amount of electrons flowing through the skin of the conduit (gold, silver, iron, copper). Electrons travel on the surface of the conduits. This called the current, and is measured in amperes.
Voltage is what pushes amperes to flow through the conduit which offers some resistance, measured in ohms.
For more info, see Wikipedia's article on Amperes
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Factors which determine the amplitude of the voltage induced in a conductor which is cutting magnetic lines of force:
Factors which determine the amplitude of the voltage induced in a conductor which is cutting magnetic lines of force:
All of the above
Flux density
Velocity that the conductor cuts the magnetic lines of force
The angle at which the conductor cuts through the magnetic lines of force
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An electrical potential may be generated by:
An electrical potential may be generated by:
All of the above
The potential refers to the energy that can be concentrated by various methods.
For more info, please see Wikipedia's article on Electric Potential
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Ohm's law is stated as:
All of the above
For more info, please see Wikipedia's article on Ohm's law
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The unit of electrical power is:
strong text- Watt
strong text- Joule per second
Electric power is the amount of energy transferred through the conduit, and is measured in watts, which is Joules per second. It can be thought of as the amount of power, which reflects the "work done" per second. The "work done" is also called Joule unit.
For more info, please see Wikipedia's article on Electric power
Also, see article Is one joule per second equivalent to one watt?
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The unit of conductance is:
Mho
Conductance is the opposite of resistance. The resistance is measured in Ohms, but conductance is measured in Mho's. The Mho, is the 1/ohm, that is the Mho is the reciprocal of Ohm.
For more info, please see ElectronicNotes' site article Electrical Conductivity: mho, siemens
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The unit of inductance is:
Henry
The inductance is the magnetic field caused by the flow of current, and this field works like resistance to the current flow. The unit of inductance, Henry, refers to Joseph Henry who discovered inductance.
For more info, see Wikipedia's article Inductance Also, see article on Joseph Henry
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The ratio of current through a conductor to the voltage which produces it is:
The ratio of current through a conductor to the voltage which produces it is:
Conductance
It measures how well electricity flows through the skin of the substance such as silver, gold, copper, iron, etc.
For more info, see Electrical4U site, article Conductance: What is it? (Definition, Units & Formula)
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The product of the number of turns and the current in amperes used to describe relative magnitude is:
The product of the number of turns and the current in amperes used to describe relative magnitude is:
Ampere turns
When you run electric current through wires that were wound in a circular pattern, you get a magnetic field that is strong. In fact, whenever you run current, there is a magnetic field. In the coil, the field is strong because the field goes through the center of the coil.
The more turns in the coil, then there is more magnetic field created.
For more info, see Wikipedia's article Electromagnetic coil
and Tesla Scientific site's Ampere-Turn Calculator
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The property of a conductor or coil which causes a voltage to be developed across its terminals when the number of magnetic lines of force in the circuit or coil is changed is:
The property of a conductor or coil which causes a voltage to be developed across its terminals when the number of magnetic lines of force in the circuit or coil is changed is:
Inductance
The inductance is the magnetic field caused by the flow of current, and this field works like resistance to the current flow. The unit of inductance, Henry, refers to Joseph Henry who discovered inductance.
For more info, see Wikipedia's article [Inductance][1] Also, see article on [Joseph Henry][2]
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The charge of electricity which passes a given point in one second when a current of one ampere is flowing is:
The charge of electricity which passes a given point in one second when a current of one ampere is flowing is:
Coulomb
Coulomb has been adopted as the internationally recognized amount of electric charge, which is the amount of amperes (electrons flowing) per second.
For more info, see Wikipedia's article on Coulomb
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C = capacity in farads. Q = the measure of the quantity of charge of electricity in Coulombs. E = the applied voltage. So Q = CE:
C = capacity in farads.
Q = the measure of the quantity of charge of electricity in Coulombs.
E = the applied voltage.
So Q = CE:
Determines the quantity of charge in a capacitor
Coulomb or amount of amperes =
Farads (ability to store electricity) x
Voltage (the amount of difference between two unit's charges or the amount of force pushing of electrons from a unit to another)
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Resistance is:
Resistance is:
All of the above
The amount of resistance (in Ohms) that the electrons (in Amperes) experience when are pushed through a conductor by Voltage pressure.
For more info, see Fluke's site article on What is resistance?
and Wikipedia's article on Electrical resistance and conductance
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The unit of AC impedance in a circuit is:
Ohm
The amount of resistance (in Ohms) that the electrons (in Amperes) experience when are pushed through a conductor by Voltage pressure.
In AC current, the resistance changes the shape of the electrical wave (sinusoidal waveform)
For more details, see Electronic Tutorials' site article AC Resistance and Impedance
For more info, see Fluke's site article on What is resistance?
and Wikipedia's article on Electrical resistance and conductance
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The unit of capacitance is:
A & B
Ability to store electrons (amperes) in a medium is measured by Farad units. Capacitors are used to store electric charges. Since a unit of Farad has a substantial charge, for smaller charges a microfarad unit is used to measure.
For more info, see Fluke's article on What is capacitance?
and Wikipedia's article on Capacitance
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Decibel is:
Decibel is:
Both A & B
The unit used to express the ratio between two sound power levels
The unit used to express the ratio between two electrical power levels
Basically, the amount of push on air, air pressure, is measured in decibels. Decibels increase in logarithmic units, not arithmetical units.
For more info, see Physclips' article on dB: What is a decibel?
and Wikipedia's article on Decibel
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What factors determine the charge stored in a capacitor?
What factors determine the charge stored in a capacitor?
Both A & B
Capacitors store electrical charges when pressure is placed on electrons to move (applied voltage) to a capacitor.
The ability to store electrons (amperes) in a medium is measured by Farad units. Capacitors are used to store electric charges. Since a unit of Farad has a substantial charge, for smaller charges a microfarad unit is used to measure.
For more info, see Fluke's article on What is capacitance?
and Wikipedia's article on Capacitance
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Ohm's law for AC circuits when I = amperes, E = volts, Z = impedance in volts is:
Ohm's law for AC circuits when
I = amperes,
E = volts,
Z = impedance in volts is:
(D). All of the above
It appears that the Z=Z/I in answer C maybe simply misprint
I = E / R Current = Voltage / Resistance
E = IR Voltage = Current x Resistance
R = E / I Resistance = Voltage / Current
For more info, please see Wikipedia's article on Ohm's law
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The formula for determining the power in a DC circuit when the voltage and resistance are known is:
The formula for determining the power in a DC circuit when the voltage and resistance are known is:
(A). P = ( E squared) R
Power is measured in watts, or in units of Joule per second.
Watts = Amperes x Voltage or
Watts = (Amperes)2 x Resistance or
Watts = (Voltage)2 / Resistance
For more info, see Electrical Technology site's article on Power Formulas in DC and AC Single-Phase & Three-Phase Circuits
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The formula for finding power in a DC circuit when current and resistance are known:
The formula for finding power in a DC circuit when current and resistance are known:
(B). P = ( I Squared) R
Power is measured in watts, or in units of Joule per second.
Watts = Amperes x Voltage or
Watts = (Amperes)2 x Resistance or
Watts = (Voltage)2 / Resistance
For more info, see Electrical Technology site's article on Power Formulas in DC and AC Single-Phase & Three-Phase Circuits
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The formula for finding power in a DC circuit when current and voltage are known:
The formula for finding power in a DC circuit when current and voltage are known:
(A). P = EI
Power is measured in watts, or in units of Joule per second.
Watts = Amperes x Voltage or
Watts = (Amperes)2 x Resistance or
Watts = (Voltage)2 / Resistance
For more info, see Electrical Technology site's article on Power Formulas in DC and AC Single-Phase & Three-Phase Circuits
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The prefix " kilo " means:
The prefix " kilo " means:
(A). To multiply by 1000 whatever quantity follows
Kilo means a thousand, or 10 to 3rd power, or 10x10x10
For more info, see Wikipedia's article on Kilo-
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The prefix " micro " means:
The prefix " micro " means:
(A). Divide by 1,000,000 whatever quantity follows
Micro is a one millionth of a unit, or 10 to minus 6.
To get 10 to minus 6, move the decimal 6 positions from unit 1, or so 0.000 001
10 to minus 1 is 0.1 or deci-
10 to minus 2 is 0.01 or centi-
10 to minus 3 is 0.001 or mili-
For more info, please see Wikipedia's article on Micro-
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The factor by which the product of volts and amperes must be multiplied to obtain true power is:
The factor by which the product of volts and amperes must be multiplied to obtain true power is:
(A). Power factor
Power is measured in watts, or in units of Joule per second.
Watts = Amperes x Voltage or
Watts = (Amperes)2 x Resistance or
Watts = (Voltage)2 / Resistance
For more info, see Electrical Technology site's article on Power Formulas in DC and AC Single-Phase & Three-Phase Circuits
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The prefix " meg " means:
The prefix " meg " means:
(A). Multiply by 1,000,000 whatever quantity follows
Mega is the unit multiplied by 10 to 6th power. (10)6, which is 10x10x10x10x10x10 = 1,000, 000
For more info, see Wikipedia's article on Mega-
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Factors which influence the resistance of a conductor:
Factors which influence the resistance of a conductor:
(D). All of the above
The resistance of a conductor is affected by:
For more information, see Engineering Educators site article on Factors Affecting Resistance
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Halving the cross-sectional area of a conductor will:
Halving the cross-sectional area of a conductor will:
(A). Double the resistance
The resistance of a conductor is affected by:
For more information, see Engineering Educators site article on Factors Affecting Resistance
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Name four conducting materials in order of their conductivity.
Name four conducting materials in order of their conductivity.
(B). Silver, gold, zinc, platinum
For more information, see Engineering Educators site article on Factors Affecting Resistance the "Figure 41. Resistivity table," for measurements of resistivity.
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Good insulators at radio frequencies are:
Good insulators at radio frequencies are
(D). A & B
What makes a good insulator is not just lack of conductivity, but also the effect of sunlight, especially ultraviolet waves (being highly energetic) they degrade the insulating material.
Well illustrated info on ThoughtCo article 10 Examples of Electrical Conductors and Insulators Things That Don't Conduct Electricity and Things That Do
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A resistance across which a constant voltage is applied is doubled. What power dissipation will result?
A resistance across which a constant voltage is applied is doubled. What power dissipation will result?
(A). One half
The resistance of a conductor is affected by:
For more information, see Engineering Educators site article on Factors Affecting Resistance
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The needle of a magnetic compass when placed within a coil carrying an electric current:
The needle of a magnetic compass when placed within a coil carrying an electric current:
(D). A & B
For more details, please see Siyavula Technology-Powered Learning site, article on 10.2 Magnetic field associated with a current
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Electrical resistance is measured with:
Electrical resistance is measured with:
(A). An ohmmeter
The meter measures how much a substance prevents the flow of electrons (current) through its surface skin, known as the electrical resistance, and expressed in ohm units.
For more info, see Elprocus site, for article on What is an Ohmmeter? Circuit Diagram, Types and Applications
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The sum of all voltage drops around a simple DC circuit, including the source, is:
The sum of all voltage drops around a simple DC circuit, including the source, is:
(A). Zero
That is just the definition of changes in voltage in a simple DC circuit. This called the Kirchhoffs' Voltage Law, or the Law of Conservation of Energy.
The law declares that:
"'in any closed loop network, the total voltage around the loop is equal to the sum of all the voltage drops within the same loop.'”
This means that if you sum all the volts in the components, the sum will be zero.
For more info, see Electronics Tutorials site, article on Kirchhoffs Circuit Law
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If a resistance to which a constant voltage is applied is halved, what power dissipation will result?
If a resistance to which a constant voltage is applied is halved, what power dissipation will result?
(A). Doubled
The resistance of a conductor is affected by:
For more information, see Engineering Educators site article on Factors Affecting Resistance
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The diameter of a conductor six inches long is doubled, what will be the effect on the resistance?
The diameter of a conductor six inches long is doubled, what will be the effect on the resistance?
(D). A & C
One-fourth the original value
The resistance varies inversely with the cross-sectional area of the conductor
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A minute subdivision of matter having the smallest known unit of negative electrical charge is:
A minute subdivision of matter having the smallest known unit of negative electrical charge is:
(A). Electron
If you have more negative electrons than positive protons, then you have a negative electric charge.
For more info, please see Wikipedia's articles on Electron and Electric charge
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Conductors differ from nonconductors, i.e.:
Conductors differ from nonconductors, i.e.:
(D). A & B
There are a large number of free electrons in a good conductor
There is a small number of free electrons in a non-conductors stop the flow of electrons.
Conductors facilitate flow of electrons across their skin surface, while nonconductors do not allow the
Conductance is the opposite of resistance. The resistance is measured in Ohms, but conductance is measured in Mho's. The Mho, is the 1/ohm, that is the Mho is the reciprocal of Ohm.
For more info, please see ElectronicNotes' site article Electrical Conductivity: mho, siemens
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Direction of flow of DC electricity in a conductor can be determined by:
Direction of flow of DC electricity in a conductor can be determined by:
(D). A & C
Direct Current occurs when electrons flow in a one direction only. Electronic circuits use mostly direct current from a battery or a direct current transformer.
More info on Wikipedia's article on Direct current
The flow of electrons in the same direction (DC current) creates a magnetic field. The magnetic field propagates clockwise around the surface skin of the conductor material. The compass needle will be affected by the magnetic field.
More info on Wikipedia's article on Magnetoresistance
By introducing a magnetic field to a flow of electrons in one direction, there will be created a force that is at 90 degrees (perpendicular) to the magnetic field and the flow of electrons.
On a graph, this force would be on the Y axis, while flow and magnetic force on the X axis. For simplicity, your thumb would be the force, while the index finger would show the magnetic force, while the middle finger would show a flow of electrons.
More info on Wikipedia's article on Magnetoresistance
There are various versions of the interaction of force, magnetic field, and current. Mostly, they are called either a left-hand or right-hand rule. These two are opposite of each other.
The left-hand rule shows the flow of current to produce motion, as in electric motors. The right-hand rule is the opposite, as it creates current, not using it, in generators of electricity.
See detailed explanation on Wikipedia's article Fleming's left-hand rule for motors
In the past, an instrument called "Galvanometer" was used to measure DC current. An improved version which did not require interrupting the electrical circuit is called an "Ammeter" It measures current in amperes.
For more info, please see Wikipedia's article on Ammeter
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The difference between electrical power and electrical energy is:
The difference between electrical power and electrical energy is:
(C). A & B
Good simple definitions.
For more info, please see Wikipedia's articles on Electric power
and Electrical energy
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A positive temperature coefficient means:
A positive temperature coefficient means:
(C). Both A & B
For greater insights, please see Wikipedia's article on Temperature coefficient
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A liquid which is capable of conducting electricity, but undergoes decomposition while doing so is:
A liquid which is capable of conducting electricity, but undergoes decomposition while doing so is:
(A). An electrolyte
Liquids with the ability to allow flow of current is called an electrolyte.
For more details, please see Wikipedia's article on Conductivity (electrolytic)
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The effective value of an RF current and the heating value of the current are:
The effective value of an RF current and the heating value of the current are:
(A). The same
For greater insights, please see Wikipedia's article on Temperature coefficient
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One horsepower is:
One horsepower is:
(D). All of the above
The horsepower measurement reflects the amount of work done as one unit. There are several different horsepower measurement.
For more info, please see Wikipedia's article on Horsepower
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What factors determine the heat generated in a conductor?
What factors determine the heat generated in a conductor?
(C). Both A & B
Heat generated in a conductor is:
For greater insights, please see Wikipedia's article on Temperature coefficient
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What is the ratio of peak to average value of a sine wave?
What is the ratio of peak to average value of a sine wave?
(D). A & B
There are a number of formulas for calculating the avg value of sine wave for different waves. The 1.57 refers to the "half wave rectified sine wave." The "full rectified wave" is 0.637.
For more details, see Electrical Technology site, article on RMS Value, Average Value, Peak Value, Peak Factor And Form Factor in AC
and, site All About Circuits article on Measurements of AC Magnitude
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When the current sine wave in a circuit reaches its peak value before the voltage wave:
When the current sine wave in a circuit reaches its peak value before the voltage wave:
(A). It is said to have a leading power factor
When the electron flow (amperes) is at max before the max in amount of charge (electrons) differential (volts), then we have a leading power factor.
Power is the ability of voltage (push) and amperes (electron flow) to do a unit of work. If you apply root-means-square formula to the amperes and volts, you get "apparent power."
If you imagine that horizontal line is the real power, and at an angle from that line is another line, called apparent power, then the difference between apparent power and real power is the reactive power. (such a fun fact)
If the apparent power line is below the horizontal real power line, then we have the leading power factor If the apparent power line is at an angle above the horizontal real power line, then we have lagging power factor.
"Capacitive loads are leading (current leads voltage), and inductive loads are lagging (current lags voltage)."*
*For more insights, please see Wikipedia's article on Power Factor
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An "harmonic" is:
An "harmonic" is:
(A). A whole multiple of an original frequency
Harmonic is the same note, but some octaves higher. The wave from zero to max back to zero is divided by a number such as 1,2, or 3 or more.
When you divide the wave it occurs at a higher Hz, at a multiple of the initial Hz wave. So, if the initial wave is at 440 Hz, then the second harmonic will be at 880 Hz, and there will be two waves in the time unit of the initial one.
The 3rd harmonic will have three smaller waves in the time unit of the initial wave, and the initial frequency in Hz will be multiplied by 3.
Harmonics are important in music and radio waves. In radio waves, there are circuits to eliminate the harmonics of the frequency desired, to suppress interference.
For more info, please see Wikipedia's article on Harmonic
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Assuming a power source to have a fixed value of internal impedance, maximum power will be transferred to the load when:
Assuming a power source to have a fixed value of internal impedance, maximum power will be transferred to the load when:
(A.) The load impedance equals the internal impedance of the source
Impedance is the resistance to alternating current. Impedance is created by the resistance (opposition to flow of electrons, in ohms) and reactance. Reactance includes inductive and capacitive components.
See Wikipedia's article on Electrical Impedance
Impedance matching seeks to maximize the amount of power transferred while minimizing the reflection from the load transferred.
Basically, if the impedance of the input load is the same as the internal impedance of the output (the source), then the maximum amount of power is transferred.
For more info, see Wikipedia's article on Impedance matching
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When two sine waves of the same frequency do not reach their maximum or minimum values simultaneously:
When two sine waves of the same frequency do NOT reach their maximum or minimum values simultaneously:
(D). A & C
Alternating current creates a sine wave as electric motor rotates between north and south magnetic poles in a coil. See Electronic Tutorials Sinusoidal Waveforms article.
When voltage sine wave leads current (ELI) inductance is the result. When current sine wave leads voltage (ICE), then result is capacitance.
(ELI the ICE man)
E voltage, L inductor, I current;
I current, C capacitor, E voltage
Please see Wikipedia's animated illustration on the relationship of Phases and Sine waves. You can see that when there is no phase difference, the combined sine wave is at maximum.
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Which method may be used to obtain more than one value of voltage from a fixed DC source?
Which method may be used to obtain more than one value of voltage from a fixed DC source?
(C). Both A & B
Use a resistance type voltage divider
Connect voltage regulator tubes of suitable values and tap off the desired output voltage
For insights regarding DC current, please see IQS Directory site's article on DC Power Supply
For well illustrated practical application of variable DC current, please see How To Get Variable Voltage From a Fixed DC Power Supply
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The conductance (G) of a circuit if 6 A flows when 12 VDC is applied is:
The conductance (G) of a circuit if
6 A flows when
12 VDC is applied is:
(A). 0.5 mho
mho is the 1/ohms yielding conductance.
Conductance (G), is 1/R or I/V.
G = 6 A / 12 VDC = 0.5 mho
For more info, please see Wikipedia's article on Electrical resistance and conductance
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Two 10 W, 500 ohm resistors in parallel will dissipate how many watts?
Two (2) 10 W,
500 ohm resistors
in parallel will dissipate how many watts?
(A). 20 watts
Formulas for power dissipation:
Watts = Volts x Amperes or
Watts = Volts(2) / Ohms or
Watts = Amperes(2) x Ohms
Because both resistors in parallel are the same value:
2 quantity (each 500 ohms) x 10 Watts = 20 Watts
For more info, please see All About Circuits site, article Power Calculations Chapter 5 - Series And Parallel Circuits
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A 20 ohm resistor with a current of 0.25 A passing through it will dissipate how many watts?
A 20 ohm resistor with a current of
0.25 A passing through it
will dissipate how many watts?
(D). 1.25 watts
Watts = Volts x Amperes or
Watts = Volts(2) / Ohms or
Watts = Amperes(2) x Ohms
Watts = 0.25 A (2) x 20 ohms
Watts = 0.0625 A x 20 ohms
Watts = 1.25
For more info, please see All About Circuits site, article Power Calculations Chapter 5 - Series And Parallel Circuits
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If the voltage to a circuit is doubled and the resistance is increased to three times the original value, what will be the final current?
If the voltage to a circuit is doubled
and the resistance is increased to three times the original value,
what will be the final current?
(B). 2/3 the original current
Voltage x 2 and Resistance * 3 ==> Amperes?
Voltage = Amperes x Ohms
Amperes = Voltage / Ohms
Amperes = 2V/3R which is 2/3 original amperes
For more info, please see Electrical 101 site article on Ohm’s Law
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If a vacuum tube with a filament rating of 0.25 A and 5 V is operated from a 6 volt battery, what value of resistor is necessary?
If a vacuum tube with a filament rating of
0.25 A and
5 V is operated from a
6 volt battery,
what value of resistor is necessary?
(A). 4 ohms
Ohms = Volts / Amperes
Ohms = 6 volts / 0.25 Amperes = 24
Ohms = 5 volts / 0.25 Amperes = 20
24 ohms - 20 ohms = 4 ohms
For more info, please see All About Circuits site, article Power Calculations Chapter 5 - Series And Parallel Circuits
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The minimum power dissipation rating of a resistor of 20,000 ohms across a potential of 500 V should be:
The minimum power dissipation rating of a resistor of
20,000 ohms across a potential of
500 V should be:
(A). 25 watts
Watts = Volts(2) / ohms
Watts = 500 ohms (2) / 20,000 = 12.5 watts
12.5 watts x 2 = 25 watts
For more info, please see All About Circuits site, article Power Calculations Chapter 5 - Series And Parallel Circuits
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The total power dissipation capability of two 10 watt, 500 ohm resistors connected in series is:
The total power dissipation capability of
two 10 watt,
500 ohm resistors
connected in series is:
(A). 20 watts
Formulas for power dissipation:
Watts = Volts x Amperes or Watts = Volts(2) / Ohms or Watts = Amperes(2) x Ohms
Because both resistors in parallel are the same value: 2 quantity (each 500 ohms) x 10 Watts = 20 Watts
For more info, please see All About Circuits site, article Power Calculations Chapter 5 - Series And Parallel Circuits
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What is the total power dissipation capability of two 10 watt 500 ohm resistors connected in parallel?
What is the total power dissipation capability of
two 10 watt
500 ohm resistors
connected in parallel?
(A). 20 watts
Formulas for power dissipation:
Watts = Volts x Amperes or Watts = Volts(2) / Ohms or Watts = Amperes(2) x Ohms
Because both resistors in parallel are the same value: 2 quantity (each 500 ohms) x 10 Watts = 20 Watts
For more info, please see All About Circuits site, article Power Calculations Chapter 5 - Series And Parallel Circuits
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What is the maximum current carrying capacity of a resistor of 5000 ohms, 200 watts?
What is the maximum current carrying capacity of a resistor of
5000 ohms,
200 watts?
(A). 0.2 A
Watts = Volts x Amperes or
Watts = Volts(2) / Ohms or
Watts = Amperes(2) x Ohms
200 watts = 5000 ohms x X(2) Amperes
X(2) = 200 / 5000 = Square Root of 0.04 = 0.2 A
For more info, please see All About Circuits site, article Power Calculations Chapter 5 - Series And Parallel Circuits
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What is the total resistance of a parallel circuit consisting of a 10 ohm branch and a 25 ohm branch?
What is the total resistance of
a parallel circuit consisting of a
10 ohm branch and a
25 ohm branch?
(D). 7.14 ohms
To sum up parallel resistors, you need to take the reciprocal of the resistors.
1/10 + 1/25 = 0.1 + 0.04 = 0.14,
so reciprocal of 1/0.14 =7.14
For more info, please see All About Circuits site, article Parallel Resistance Calculator
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The current through two resistors in series is 3 A. Resistance #1 is 50 ohms, resistance #2 drops 50 V across its terminals. What is the total voltage?
The current through two (2) resistors in series is
3 A. Resistance
#1 is 50 ohms, resistance
#2 drops 50 V across its terminals.
What is the total voltage?
(A). 200 V
Voltage = Amperes x Resistance
3 Amperes x 50 Ohms = 150 Volts
since 50 Volts drop is given,
then 150 V + 50 V = 200 V
For more information, please see Sciencing site article on How to Calculate a Voltage Drop Across Resistors
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An 18 ohm and a 15 ohm resistor are connected in parallel; a 36 ohm resistor is connected in series with this combination; a 22 ohm resistor is connected in parallel with this total combination. The total current is 5 A. What current is flowing in the 15 ohm resistor?
An 18 ohm and a 15 ohm resistor are connected in parallel;
a 36 ohm resistor is connected in series with this combination;
a 22 ohm resistor is connected in parallel with this total combination.
The total current is 5 A.
What current is flowing in the 15 ohm resistor?
(A). 0.908 A
Amperes = Volts / Resistance.
(1) In parallel
1/18 + 1/15 = 15/ 270 + 18 / 270 = 33 / 270 = 0.122 or about 8.18
(2) In series
8.18 + 36 = 36.122 = 44.18 ohms
(3) In parallel
44.18 ohms + 22 ohms = 14.686 ohms
(4) To derive Volts
14.686 ohms x 5 Amperes = 73.43 Volts
Then, you have to work back Amperes to the 15 ohm resistor. Calculate branch currents without voltage
Remember, Amperes flow through series unchanged, but divide in parallel, depending on the resistor.
For more info on parallel and series circuits, see BCampus site article 63 Resistors in Series and Parallel
For more information, please see Sciencing site article on How to Calculate a Voltage Drop Across Resistors
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A circuit passes 3 A. The internal resistance of the source is 2 ohms. The total resistance is 50 ohms. What is the terminal voltage of the source?
A circuit passes 3 A.
The internal resistance of the source is 2 ohms.
The total resistance is 50 ohms.
What is the terminal voltage of the source?
(A). 150 V
The formula V=IR can be used.
3Ampers x 50 Ohms = 150 Volts
For more info, see Science by Degrees site's article Why V=IR is not Ohm’s Law, and why that matters
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A relay coil has 500 ohms resistance, and operates on 125 mA. What value of resistance should be connected in series with it to operate from 110 VDC?
A relay coil has
500 ohms resistance, and operates on
125 mA. (0.125 A)
What value of resistance should be connected in series with it to operate from 110 VDC?
(A). 380 ohms
For resistance in series circuits, you simply add resistance of each component. See Understanding & Calculating Series Circuits Basic Rules from swtc.edu
V=IR
110 V = (500 ohms + X ohms) * .125 A
(500 ohms + X ohms) = 110 v / .125 A
(500 ohms + X ohms) = 880 ohms
X = 880 ohms - 500 ohms = 380 ohms
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Given: Input power to a receiver is 75 watts. How much power does the receiver consume in 24 hours of continuous operation?
Given: Input power to a receiver is 75 watts. How much power does the receiver consume in 24 hours of continuous operation?
(C). A & B
Both answers are the same.
Kilo is 1000, so 1800/1000=1.80
75 Watts x 24 hours = 1,800 Watts
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The total reactance when two capacitances of equal value are connected in series is:
The total reactance when two capacitances of equal value are connected in series is:
(B). The sum of the two individual reactances in ohms
For insight, please see Lumen Physics site the article on Resistors in Series and Parallel also Capacitors in Series and Parallel
And, from Electronics Tutorials site the article on Capacitors in Series, and Capacitors in Parallel
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A capacitor's charge is stored:
A capacitor's charge is stored:
(C). A & B
Upon the inner surface of the capacitor plates
As an electrostatic field which exists in the space between the plates
For details, please see OPENPRESS.USASK.CA site article on 4.3 Energy Stored in a Capacitor
Also, see Lumen Physics site article on Energy Stored in Capacitors
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The voltage drop across an individual capacitor of a group of capacitors connected in series across an AC source is:
The voltage drop across an individual capacitor of a group of capacitors connected in series across an AC source is:
(D). All of the above
Inversely proportional to the ratio of the capacitance of the capacitor being considered
Inversely proportional to the total capacitance of the combination
Directly proportional to the applied voltage across the series combination
For more info, please see Electronics Tutorials site article Capacitors in Series
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What is the total capacitance of the capacitors of 3, 5, and 7 microfarad connected in series?
What is the total capacitance of the capacitors of 3, 5, and 7 microfarad connected in series?
(B). 1.479 microfarad
1/3 is 0.33333333333
1/5 is 0.2
1/7 is 0.14285714285
The total is 0.67619014285 and the reciprocal 1/67619014285 is 1.479
For more info, see Lumen Physics article on Capacitors in Series and Parallel
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If capacitors of 3, 5, and 7 microfarad are connected in parallel, what is the total capacitance?
If capacitors of 3, 5, and 7 microfarad are connected in parallel, what is the total capacitance?
(A). 9 microfarad
The formula calls for simple addition, which comes to 15, and not 9. Seems like an error. Best, just remember that answer. Checked in the FCC Element 6 question pool, and it is 9.
For more info, see Lumen Physics article on Capacitors in Series and Parallel
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How many capacitors of 400 volts and 2 microfarad each would be necessary to obtain a combination rated at 1600 volts and 1.5 microfarad?
How many capacitors of
400 volts and
2 microfarad each would be necessary to obtain a combination rated at
1600 volts and
1.5 microfarad?
(B). 12
Please see Physics Forum site for explanation of the answer.
See DigiKey Electronics for Series and Parallel Capacitor Calculator
See Open Press site for 6.3 Kirchhoff’s Rules
For basic info, see Electronics Tutorials site for Capacitance and Charge
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If a turn in an inductor is shorted:
If a turn in an inductor is shorted:
(D). All of the above
There will be:
The question does not specify whether it is a DC or AC circuit. One property of an inductor is that it resists changes in amperes.
However, the inductance to the flow of amperes is not the same in DC and AC circuits, measured in di/dt, or change in amperes per change in a unit of time. In DC circuits, the coil stores energy, in AC circuits, the coil stores and delivers energy.
Because of the change (decrease in induction), the flowining amperes may overheat the circuit.
Coils do have some resistance, Q, and short may cause a decrease in Q, as it causes some energy loss.
For more info on inductors (chokes), please see Electronic Tutorials site for article on The Inductor
and for even more details, please see Voltech website for the article on Methods for Detection of Shorted Windings
Regarding Q in coils, please see Electronics Notes article on Inductor Q, Quality Factor
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The relationship between the number of turns and the inductance of a coil may be expressed by:
The relationship between the number of turns and the inductance of a coil may be expressed by:
(A). The inductance varies approximately as the square of the number of turns
For more info, please see Quora article on Why is inductance (L) proportional with turns-square (N²)?
and Electronics Tutorial article on Inductance of a Coil
For more info on inductors (chokes), please see Electronic Tutorials site for article on The Inductor
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The formula for determining the resonant frequency of a circuit when the inductance and capacitance are known is:
The formula for determining the resonant frequency of a circuit when the inductance and capacitance are known is:
(C). Both A & B
f = 1/(2 pi times the square root of LC)
f = 0.159/(the square root of LC)
When you graph frequency on X axis, and reactance on Y axis, the inductive reactance is a straight 45 degrees line, but the capacitive reactance curve starts high and decreases as frequency increases.
At the intersection of both, there is the resonant frequency for a specific circuit. It is when the inductive and capacitive reactance are equal. For more info, please see Cadence site, article on What is Resonant Frequency?
Also, for more details see Electronics Tutorials article on Series Resonance Circuit
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The formula for determining the wavelength when the frequency is known is:
The formula for determining the wavelength when the frequency is known is:
(D). All of the above
Wavelength = 300,000/ f kHz
Wavelength = 300,000,000/ f Hz
Wavelength = 300/ f MHz
For graphic explanation, see wikiHow article on How to Calculate Wavelength,
and on Study site, How to Calculate Wavelength, which offers a video and info.
For explanation on metric system of units, kilo, and mega, see Wikipedia's article on Metric prefix
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The wavelength of the period of one complete cycle of a radio wave of 0.000,001 second is:
The wavelength of the period of one complete cycle of a radio wave of 0.000,001 second is:
(A). 300 M
Since waves travel in vacuum at 300,000 km/second, or 3,000,000 meters per second, multiply by 1,000,000 to get the second, or 300 M (M=1,000,000).
For details, see Socratic Q&A site article on How can I calculate the wavelength of electromagnetic radiation?
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The efficiency of a radio device is:
The efficiency of a radio device is:
(B). The ratio of the useful power output to the power input
Generally, efficiency of any system is the cost or amount of what is provided, and the benefits achieved.
For radio, it is the amount of energy as input, and the amount of energy as output, with the difference being radiated during the processing.
For more info, see Socratic Q&A site for How can energy efficiency be calculated?
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What is the total impedance of a parallel capacitor and inductor with equal values of reactance?
What is the total impedance of a parallel capacitor and inductor with equal values of reactance?
(D). B & C
For explanation of impedance and reactance please see Electronics Tutorial site for article on Impedance and Complex Impedance
Also, see EE Power site for article on Impedance and Reactance
Specific explanation here on Electrical Engineering article on Infinite impedance at resonance in parallel LC circuit ? does that mean it is not usable?
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The total inductance of two coils in parallel without any mutual coupling is:
The total inductance of two coils in parallel without any mutual coupling is:
(A). Equal to the product of the two inductances divided by their sum
If coupling in the circuit of two coils present, then the total amount of inductance will be affected by the total amount of coupling.
For explanation of the formula, please see Electronics Tutorial site, for the article on
Inductors in Parallel,
paragraph on the "Parallel Inductor Equation."
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What is the total reactance of a series AC circuit, with no resistance and equal inductance and capacitive reactances?
What is the total reactance of a series AC circuit, with no resistance and equal inductance and capacitive reactances?
(D). All of the above
For full explanation, please see Electronics Tutorials article on AC Inductance and Inductive Reactance
Also, a great article on Reactance, Inductive and Capacitive listed on the Lumen Learning site.
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The total inductance of two coils in series without any mutual coupling is:
The total inductance of two coils in series without any mutual coupling is:
(A). The sum of the individual inductances
If coupling in the circuit of two coils present, then the total amount of inductance will be affected by the total amount of coupling.
For explanation of the formula, please see Electronics Tutorial site, for the article on
Inductors in Parallel,
paragraph on the "Parallel Inductor Equation."
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One wave-length is:
One wave-length is:
(C). A and B
The distance a wave will travel in the time for one cycle
Centimeter wavelength = 30,000 / frequency MHz
Need to watch out for the units of measure here. We know that light travels at the speed of 300,000,000 meters per second.
The standard formula for wavelength is 300,000,000 meters/second or 300M divided by radio frequency in Hz.
The time unit for the wave is a second. Thus, we state that so many waves occurred in one second.
So, if we use MHz instead of Hz, then we have to adjust the units of speed of light in the formula.
We know that 1 MHz equals to 1,000,000 Hz. And, we know that there are 100 centimeters in a meter.
Then, if we multiply the 300,000,000 meters/second by 100 centimeters/one meter, we get 30,000,000,000 centimeters/second.
To convert Hz to MHz, we must divide by 1,000,000 Hz in 1 MHz, to get 30,000 centimeters per MHz.
Please see NewHams.Info site article on Wavelength. This site is a good resource for various radio topics.
To calculate wavelengths, and try out various units, please see Wavelength Calculator site for Wavelength Calculator
BTW: A great listing of FCC radio frequency allocations is an FCC Online Table Frequency Allocations. Good to print out and keep as reference for when choosing frequencies.
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In an AC circuit, a series inductance acting alone:
In an AC circuit, a series inductance acting alone:
(A). Causes the current to lag the applied voltage by 90 degrees
For AC inductance, it is the resistance to the change in current or amperes, expressed in Henry units. When a coil gets alternating current, it produces electrical magnetic frequency, which opposes the change in the current.
Then, volts applied through a sine wave, the volts lead current by 90 degrees, OR the current LAGS voltage by 90 degrees.
For more info, please see Electronics Tutorials site, article on AC Inductance and Inductive Reactance, subsection "Sinusoidal Waveforms for AC Inductance."
Also, see TutorialsPoint site, article on Inductors in AC Circuits.
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Shock excitation into an L-C circuit is the result of:
Shock excitation into an L-C circuit is the result of:
(D). All of the above
To produce vibrations, like resonance, you have to hit it, such as a glass to sound, a guitar string to vibrate, or a bell to sound. In electrical circuits, voltage (a difference between charges in two objects) will cause a spark to jump, or a capacitor, having two plates, maybe shocked when the difference in charges exists between the plates.
For more depth info, please see the Industrial Electronics site, for the article on Guide to Crystal Oscillators -- Review of Oscillation Principles, section 4 Self-Excited L-C Oscillator Characteristics.
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The term cathode ray usually applies to:
The term cathode ray usually applies to:
(A). A fairly high velocity electron beam
There are two guns that shoot electron beam at a storage mash. The main beam shoots "fairly high velocity electron beam," to create the picture. The other gun illuminates the mesh by shooting the low velocity electron beam. It does not interfere with the main beam.
For more info, please see Wikipedia's article on Cathode-ray tube
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Shielding an RF inductance:
Shielding an RF inductance:
(D). All of the above
When RF inductance occurs, there may be an establishment of undesirable relationship between components. A common method to prevent it is to provide shielding, which could be a physical barrier to RF inductance by absorbing radiation.
For greater insights, please see Passive Components site for article on EMI Suppression Shields: Understanding the Basics.
Also, see GCG Gowanda Components Group practical article on To Shield or Not to Shield - Part 1 It will show up in pdf format.
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The tendency of a tank circuit to keep oscillating for a time after the excitation energy has been removed is:
The tendency of a tank circuit to keep oscillating for a time after the excitation energy has been removed is:
(B). Flywheel effect
Tank circuit was so named by radio pioneers, as it reminded them of the behavior of water when pulsing disturbance is introduced.
Now, it is often referred to as the oscillatory circuit, or LC. The letter L represents this tank or resonant circuit, and the letter C stands for a capacitor. The circuit can store energy and release through resonant vibrations.
For more info and great animation, please see Wikipedia's article on LC circuit.
The concept of the "flywheel" is taken from the potter's round stone wheel which he moves with the foot, and when stopped pushing, the wheel has stored energy due to its weight that it keeps rotating.
The continuation of oscillations in LC after input current has been removed, is similarly called the "flywheel effect."
For additional info, please see Wikipedia's article on Flywheel effect
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Power factor is defined as:
Power factor is defined as:
(C). Both A&B
The ratio between the resistance and the impedance in a circuit
The ratio between the true power and the apparent power of a circuit
While resistance is used to control the flow of electrons, impedance is a resistance that arises out of the capacitive or inductive reactance. So the ratio between the two is also called the power factor, or how much power actually gets through.
For more info, please see the Linquip Technews article on Difference Between Resistance and Impedance-Resistance vs. Impedance.
Another more practical info site is the Fluke company site article on What is power factor and why is it important?
By measuring the power factor ratio, we can determine how much of available power is actually used. Wikipedia's article called the Power factor describes it as the total available power to the combination of amperes and volts (volt is the difference in charge between two items). That is what is called the difference between the "true power" and the "apparent power."
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High or low frequency oscillations occurring in circuits other than the original tank desired output frequencies are:
High or low frequency oscillations occurring in circuits other than the original tank desired output frequencies are:
(B). Parasitic oscillations
Oscillations happen when there is a change of states from A to B. It can be a regular unchanging movement which we call the sine wave. Should the movement stop, the item or current moving will find a middle point between the A and B state.
When the vibration is undesirable, such as in currents or radio waves, it is called parasitic. If you ever heard a microphone make a whining sound coming from the amplifier, you hear a mike listening to itself, or parasitic oscillations of sound. In electric systems, the EMI electromagnetic interference is called parasitic oscillation.
For more info, please see Wikipedia's article on Oscillation.
Also, an excellent concept presentation is on the ThoughtCo. website, article Oscillation and Periodic Motion in Physics.
In electric circuits, it happens when there is a connection between the output and input wiring. This is like connecting a fresh water pipe with the sewer pipe in plumbing.
For more info, please see Wikipedia's article on Parasitic oscillation.
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What are effects of parasitic oscillations?
What are effects of parasitic oscillations?
(D). All of the above
If you ever heard a microphone whine in the amplifier, you heard parasitic oscillation, which is what you don't want in a feedback, or variation in current or voltage.
Whether analog or digital processing, the undesirable feedback can occur. It occurs when part of the output is processed as input.
For more info, please see Wikipedia's article on Parasitic oscillation
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The velocity of propagation of radio frequency waves in free space is:
The velocity of propagation of radio frequency waves in free space is:
(D). All of the above
The Speed of Radio Wave == frequency times wavelength.
Thus, since the speed is 300 km per second divided by Frequency in MHz will yield the wavelength.
See EverythingRF site for Wavelength to Frequency Calculator
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To double the resonant frequency of a resonant circuit:
To double the resonant frequency of a resonant circuit:
(B). Make L and C both half their original values
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How may the Q of a parallel resonant circuit be increased?
How may the Q of a parallel resonant circuit be increased?
(C). Both A and B
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If L and C in a parallel resonant circuit resonants at 1000 kHz are so varied that their product remains constant, what will be the resulting resonant frequency?
If L and C in a parallel resonant circuit resonants at 1000 kHz are so varied that their product remains constant, what will be the resulting resonant frequency?
(C). 1 MHz
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What is the resonant frequency of a tuned circuit consisting of a 500 picofarad capacitor, a 150 microfarad tuning coil, and 10 ohms resistance?
What is the resonant frequency of a tuned circuit consisting of a 500 picofarad capacitor, a 150 microfarad tuning coil, and 10 ohms resistance?
(A). 581 kHz
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What is voltage regulation as applied to power supplies?
What is voltage regulation as applied to power supplies?
(A). The ratio of change in voltage between no load and full load to the full-load voltage output
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An EMF may be generated by sound waves by what principle?
An EMF may be generated by sound waves by what principle?
(D). All of the above
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How can you correct power factor in an electrical circuit?
How can you correct power factor in an electrical circuit?
(D). Both A and B
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Permeability is:
Permeability is:
(B). The ratio of magnetic flux density in a substance to the magnetizing force which produces it
Basically, how much a given substance can be magnetized.
For more information, please see Wikipedia's article on Permeability (electromagnetism)
And, Electronics Tutorials site for the article The Electromagnet, section Permeability of Electromagnets
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The time in seconds for a capacitor to attain 63.2 % of the applied voltage across its terminals is:
The time in seconds for a capacitor to attain 63.2 % of the applied voltage across its terminals is:
(C). Time constant
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What is the reactance of a 2-henry choke at 3000 Hz?
What is the reactance of a 2-henry choke at 3000 Hz?
(B). 37,680 ohms
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If there is no resistance in either leg of a circuit with an inductance of 5 henrys in parallel with a capacitance of 1 microfarad, what is the equivalent impedance of the parallel network circuit?
If there is no resistance in either leg of a circuit with an inductance of 5 henrys in parallel with a capacitance of 1 microfarad, what is the equivalent impedance of the parallel network circuit?
B. Infinite
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What is the total impedance of a series AC circuit having a resistance of 6 ohms, an inductive reactance of 17 ohms, and zero capacitive reactance?
What is the total impedance of a series AC circuit having a resistance of 6 ohms, an inductive reactance of 17 ohms, and zero capacitive reactance?
(C). 18 ohms
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The total impedance of a series AC circuit with an inductive reactance of 24 ohms, a resistance of 16 ohms, and a capacitive reactance of 16 ohms is:
The total impedance of a series AC circuit with an inductive reactance of 24 ohms, a resistance of 16 ohms, and a capacitive reactance of 16 ohms is:
(B). 16 ohms
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Essentials for making a good solder connection are:
Essentials for making a good solder connection are:
(D). None of the above
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For protection of personnel handling a transmitter:
For protection of personnel handling a transmitter:
A. Ground all exposed metal parts
This is to avoid human contact with a power cable.
See GT Engineering site for article on EXPOSED CONDUCTIVE PART AND GROUNDING
For overall info on electricity on vessels, see Law Resource site for ABYC E-09: Direct Current (DC) Electrical Systems on Boats 46 CFR 183.340(b)(4)
Also, please see the Code of Federal Regulations, Title 29, Subtitle B, Chapter XVII, Part 1915, for the section 29 CFR 1915.85(a) Vessel radar and communication systems.
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The ratio of peak-to-effective voltage values of a sign wave are:
The ratio of peak-to-effective voltage values of a sign wave are:
(C). Both A and B
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The opposition to the creation of magnetic lines of force in a magnetic circuit is known as:
The opposition to the creation of magnetic lines of force in a magnetic circuit is known as:
(A). Reluctance
Basically reluctance is the opposition of magnetic force, just like resistance within an electrical circuit.
For more info, please see Electrical 4 U site for the article on Magnetic Reluctance: What is it? (Formula, Units & Applications)
Also, see Wikipedia's article on Magnetic reluctance
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The ratio of magnetic flux density to the field strength is known as:
The ratio of magnetic flux density to the field strength is known as:
(B). Permeability
First, magnetic flux density (field intensity) describes how strong the magnetic force is in a material.
For a good detailed description, please see Wikipedia's article on Magnetic flux
Then, permeability is how much magnetization resulted from the application of the magnetic force.
For a good detailed description, please see Wikipedia's article on Permeability (electromagnetism)
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The magnetic force which remains in a substance after the original magnetizing force has been removed is known as:
The magnetic force which remains in a substance after the original magnetizing force has been removed is known as:
(B). Residual magnetism
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The direction of electron flow through a coil and the manner of winding the turns:
The direction of electron flow through a coil and the manner of winding the turns:
(A). Influence the direction of magnetic line of force generated by an electromagnet
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Adding an iron core to an air-core inductance:
Adding an iron core to an air-core inductance:
(A). Increases the inductance
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Electromagnets are used in:
(D). All of the above
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What will be the effect of a small increase in the number of turns upon the field strength of a single layer solenoid?
What will be the effect of a small increase in the number of turns upon the field strength of a single layer solenoid?
(C). Both A and B
Decrease in field strength if the coil length is increased
Unchanged if the spacing is reduced to keep the length constant
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Can a transformer be used with direct current?
Can a transformer be used with direct current?
(C). Both A and B
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A tube containing either a filament or cathode structure, grid, and a plate is a:
A tube containing either a filament or cathode structure, grid, and a plate is a:
(A). Triode
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A tube similar to a triode with the addition of a spirally wound screen grid between the plate and control grid is a:
A tube similar to a triode with the addition of a spirally wound screen grid between the plate and control grid is a:
(B). Tetrode
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Theoretical gain of a tube. The ratio of a small change in plate voltage to give a certain small change in plate current to a change in grid which would cause the same current:
Theoretical gain of a tube. The ratio of a small change in plate voltage to give a certain small change in plate current to a change in grid which would cause the same current:
(A). Amplification factor
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Effectiveness of the grid in causing changes of plate current:
Effectiveness of the grid in causing changes of plate current:
(D). A & B
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The maximum negative anode voltage with respect to the cathode. It equals the DC voltage at the input to the plus the peak AC voltage applied during the nonconducting portion of the cycle of operation of the tube:
The maximum negative anode voltage with respect to the cathode. It equals the DC voltage at the input to the plus the peak AC voltage applied during the nonconducting portion of the cycle of operation of the tube:
(A). Maximum inverse plate voltage
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What is the primary purpose of the control grid of the triode?
What is the primary purpose of the control grid of the triode?
(A). To provide a means of obtaining amplification
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What is the primary purpose of the screen grid of the tetrode?
What is the primary purpose of the screen grid of the tetrode?
(C). Both A & B
Reduces the grid to plate capacitance, making it unnecessary to neutralize RF amplifiers except at very high frequencies
Makes the plate current substantially independent of plate voltage, permitting much higher values of amplification
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What is the primary purpose of the suppressor grid of a pentode?
What is the primary purpose of the suppressor grid of a pentode?
(A). Is highly negative with respect to the plate and returns secondary emission to the plate, increasing the permissible gain and the tube efficiency
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Thoriated tungsten is usually used to make:
Thoriated tungsten is usually used to make:
(A). Filaments
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In what types of circuits do beam power vacuum tubes find application?
In what types of circuits do beam power vacuum tubes find application?
(C). Both A & B
As audio amplifier in the output and power stages of circuits having low to moderately high output ratings
As an RF power amplifier
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When free electrons in a conductor acquire sufficient energy to leave the conductor and pass into the surrounding space, it is expressed as:
When free electrons in a conductor acquire sufficient energy to leave the conductor and pass into the surrounding space, it is expressed as:
(B). Electron emission
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The emission of electrons from a material due to the impact of high-velocity electrons on its surface is:
The emission of electrons from a material due to the impact of high-velocity electrons on its surface is:
(B). Secondary emission
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Characteristics of a vacuum tube operating as a class A amplifier:
Characteristics of a vacuum tube operating as a class A amplifier:
(A). Low plate circuit efficiency, about 25%; practically no grid driving power; plate current flowing for 360 degrees of each cycle; practically no distortion of the output waveshape
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Characteristics of a vacuum tube operating as a class B amplifier:
Characteristics of a vacuum tube operating as a class B amplifier:
(B). Plate circuit efficiency, about 50-60%; plate current flows slightly more than 180 degrees of each cycle, medium power output
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Factors which determine bios voltage of a vacuum tube:
Factors which determine bios voltage of a vacuum tube:
(D). All of the above
Class of operation, plate supply voltage, permissible distortion
Grid signal magnitude, permissible plate dissipation, desired amplification factor
The no-signal plate current desired, the desirability of drawing grid current
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In the usual Class A amplifier:
In the usual Class A amplifier:
(A). There is no grid current
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The DC bias in a Class A amplifier:
The DC bias in a Class A amplifier:
(A). Usually is negative as measured at the grid with respect to cathode
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What is the effect of incorrect grid bias in a Class A amplifier?
What is the effect of incorrect grid bias in a Class A amplifier?
(C). Both A & B
Distortion of the output waveshape
Possible excessive plate dissipation if the bias is too low
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The approximate efficiency of a Class A vacuum tube amplifier:
(A). 20%-30%
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The approximate efficiency of a Class B vacuum tube amplifier:
(B). 60%
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The approximate efficiency of a Class C vacuum tube amplifier:
(C). 85%
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A charge due to the accumulation of negative electrons because the plate potential cannot attract all of the electrons leaving the emitter:
A charge due to the accumulation of negative electrons because the plate potential cannot attract all of the electrons leaving the emitter:
(B). Space charge
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A material flashed by the application of heat after the tube is evacuated that absorbs any gases remaining inside the tube:
A material flashed by the application of heat after the tube is evacuated that absorbs any gases remaining inside the tube:
(B). Getter
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What types of vacuum tube filaments are reactivated:
What types of vacuum tube filaments are reactivated:
(B). Thoriated tungsten
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A tungsten filament is operated at ____ temperature than a thoriated tungsten filament:
A tungsten filament is operated at ____ temperature than a thoriated tungsten filament:
(A). A higher
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The presence of gas within a tube is indicated:
The presence of gas within a tube is indicated:
(A). By a blue glow
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The cathode of an indirectly heated type of vacuum tube should be maintained at nearly the same potential as the heater circuit:
The cathode of an indirectly heated type of vacuum tube should be maintained at nearly the same potential as the heater circuit:
(C). A & B
To reduce hum pickup into the cathode
To prevent breakdown of the insulation between the heater and cathode
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Transmitting tube filaments should be maintained at recommended voltages:
Transmitting tube filaments should be maintained at recommended voltages:
(D). All of the above
To realize the greatest life-expectancy
If the filament voltage is too low, the emission will be reduced and operation of the circuit may be adversely affected
If the voltage is too high, the filament may burn out
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Use of an AC filament supply is desirable:
Use of an AC filament supply is desirable:
(A). Mostly for practical reasons. It is easily obtainable
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If a DC filament supply is used, it is advisable to periodically reverse the polarity of the filament potential:
If a DC filament supply is used, it is advisable to periodically reverse the polarity of the filament potential:
(A). To lengthen the life of the filament
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Bias voltage on the grid of an AF amplifier tube:
Bias voltage on the grid of an AF amplifier tube:
Determines the operating conditions of the tube
The correct value is essential for undistorted Class A output
In power amplifiers the plate current must be limited to safe value not to exceed the rated plate dissipation of the tube
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The screen grid in a vacuum tube:
The screen grid in a vacuum tube:
(C). A & B
Makes it unnecessary to neutralize RF amplifiers except at very high frequencies,
Makes it possible to obtain much higher values of amplification than with triodes
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The suppressor grid in a multielement vacuum tube:
The suppressor grid in a multielement vacuum tube:
(D). All of the above
Is highly negative with respect to the plate
Returns secondary electrons to the plate
Increases the permissible gain and the efficiency of the tube
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The gain of a triode audio amplifier is a function of:
The gain of a triode audio amplifier is a function of:
(D). All of the above
Tube transconduction
Plate load impedance
Transformer step-up (if used)
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"Load" on a vacuum tube commonly refers to:
"Load" on a vacuum tube commonly refers to:
(C). A & B
The impedance through which plate current flows to produce a useful output
Increases as the load impedance approaches the internal plate impedance in value
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A case in which the grid is held at an excessively negative value for a period of time thereby cutting off plate current:
A case in which the grid is held at an excessively negative value for a period of time thereby cutting off plate current:
(A). Blocked grid
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The maximum power that can be safely and continuously dissipated in heat on the plate:
The maximum power that can be safely and continuously dissipated in heat on the plate:
(A). Maximum plate dissipation
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Occurs when plate current equals electron emission for any given filament or cathode temperature:
Occurs when plate current equals electron emission for any given filament or cathode temperature:
(A). Plate saturation
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The most desirable factor in the choice of a vacuum tube for a voltage amplifier:
The most desirable factor in the choice of a vacuum tube for a voltage amplifier:
(B). A high value of transconductance
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Lack of requirement for neutralizing, except at ultra high frequencies, is an advantage of a tetrode over ____:
Lack of requirement for neutralizing, except at ultra high frequencies, is an advantage of a tetrode over ____:
(A). A Triode
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Characteristics of a vacuum tube operating as a Class C amplifier:
Characteristics of a vacuum tube operating as a Class C amplifier:
(C). High plate circuit efficiency, up to 80%; plate current drawn in bursts; great distortion of output waveshape
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Plate current flows for less than 180 degrees (about 120 degrees when the grid bias is about twice cutoff value) in what class amplifier?
Plate current flows for less than 180 degrees (about 120 degrees when the grid bias is about twice cutoff value) in what class amplifier?
(C). C.
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Tubes operated as Class C amplifiers are not suited for audio-frequency amplifiers:
Tubes operated as Class C amplifiers are not suited for audio-frequency amplifiers:
(A). Because of excessive distortion
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Low plate current may be caused by:
Low plate current may be caused by:
(D). All of the above
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A tuned circuit made up of inductance and capacitance is:
A tuned circuit made up of inductance and capacitance is:
(A). An oscillator
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Some radio-frequency amplifiers must be neutralized:
Some radio-frequency amplifiers must be neutralized:
(B). To prevent sustained oscillations from occurring in the amplifier
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Cavity resonators are:
Cavity resonators are:
(D). All of the above
For more info, please see Cadence article on What is a Cavity Resonator and How is One Used in PCB Design
Also, Wikipedia's article on Resonators
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The diode detector:
The diode detector:
(D). A & B
Is square law on weak signals
Is practically linear on strong signals
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The functioning of a grid-leak detector:
The functioning of a grid-leak detector:
(D). A & C
Depends on the ability of the grid leak and capacitor to follow the average grid current variations which are directly proportioned to the modulation envelope
Very sensitive to weak signals
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Characteristic of a square law type of vacuum tube detector:
Characteristic of a square law type of vacuum tube detector:
(D). All of the above
High sensitivity is provided due to the audio output signal amplitude being proportioned to the square of the radio frequency voltage
High percentage of second harmonic distortion
Works on weak signals only
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A diode detector ordinarily produces ____ overall distortion of the audio output wave than does a triode detector:
A diode detector ordinarily produces ____ overall distortion of the audio output wave than does a triode detector:
(A). Lower
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Operating conditions for determining that a tube is being used as a power detector:
Operating conditions for determining that a tube is being used as a power detector:
(D). All of the above
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Why is a center top usually provided for vacuum tube plate and grid return circuits when and AC filament supply is used?
Why is a center top usually provided for vacuum tube plate and grid return circuits when and AC filament supply is used?
(A). To prevent hum voltage from modulating the normal signals
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How would you determine the cathode-bias resistance necessary to provide correct grid bias for an amplifier?
How would you determine the cathode-bias resistance necessary to provide correct grid bias for an amplifier?
(D). All of the above
Bias equals the IR drop across the cathode
Bias is found by dividing the desired DC bias voltage by the total no-signal cathode current
For a tetrode or pentode, the screen current must be added to the plate current
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Given the following vacuum tube constants: Gp = 1000 V, Ip = 150 mA, Ig = 10 mA, Grid leaks = 5000 ohms. What would be the grid bias voltage?
Given the following vacuum tube constants:
Gp = 1000 V,
Ip = 150 mA,
Ig = 10 mA,
Grid leaks = 5000 ohms.
What would be the grid bias voltage?
(A). 50 V
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What currents will be indicated by a milliammeter connected between the center top of the filament transformer of a tetrode and negative high voltage?
What currents will be indicated by a milliammeter connected between the center top of the filament transformer of a tetrode and negative high voltage?
(C). Combined plate and screen grid currents
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A dynatron oscillator is a ____ which depends upon the negative resistance characteristic of a tetrode tube for its operation:
A dynatron oscillator is a ____ which depends upon the negative resistance characteristic of a tetrode tube for its operation:
(A). Tuned circuit operation
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Materials which can be used as crystal detectors:
Materials which can be used as crystal detectors:
(D). All of the above
For more info, please see Electronics Notes site, article on Crystal Detector
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A power detector may be operated:
A power detector may be operated:
(C). As either a square law detector or a linear detector
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Used to multiply the fundamental frequency by two:
Used to multiply the fundamental frequency by two:
(A). Frequency doubler
For more info, please see Mini-Circuits site article on Frequency Doublers: Introduction, definition of terms, Q&As
Also, please see Wikipedia's article on Frequency multiplier
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When used as an RF amplifier, a pentode vacuum tube:
When used as an RF amplifier, a pentode vacuum tube:
(D). A & C
Usually does not require neutralization
May require neutralization at ultra-high frequencies
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A quartz crystal in a radio transmitter:
A quartz crystal in a radio transmitter:
(C). A & B
Is used to provide a high degree of master-oscillator frequency stability
May be the sole tuned circuit in the oscillator
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Advantage of crystal control over tuned circuit oscillators:
Advantage of crystal control over tuned circuit oscillators:
(D). All of the above
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If the crystal will undergo very small changes in its operating frequency with relatively large temperature variations:
If the crystal will undergo very small changes in its operating frequency with relatively large temperature variations:
B. A low-temperature coefficient crystal
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A separate source of power is sometimes desirable for crystal-oscillator units in a transmitter:
A separate source of power is sometimes desirable for crystal-oscillator units in a transmitter:
(A). To prevent dynamic instability of the crystal oscillator
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"The temperature coefficient of an x-cut crystal is negative":
"The temperature coefficient of an x-cut crystal is negative":
(D). B & C
The operating frequency of the crystal will decrease as the temperature increases
The operating frequency of the crystal will increase as the temperature decreases
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If you apply DC voltage to the opposite plane surfaces of a quartz crystal:
If you apply DC voltage to the opposite plane surfaces of a quartz crystal:
(C). A & B
The crystal plate will always undergo a physical distortion
The crystal might crack under the strain of displacement caused by too much voltage
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"The temperature coefficient of a y-cut crystal is positive" means:
"The temperature coefficient of a y-cut crystal is positive" means:
(D). A & B
The operating frequency of the crystal will decrease as the temperature decreases
The operating frequency of the crystal will increase as the temperature increases
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Two dissimilar metals joined together and producing a current between them when the junction is heated is:
Two dissimilar metals joined together and producing a current between them when the junction is heated is:
(B). A thermocouple
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Waveguides:
Waveguides:
(D). All of the above
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Transistors may be compared to a conventional triode vacuum tube functionally:
Transistors may be compared to a conventional triode vacuum tube functionally:
(D). All of the above
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Types of transistors:
(C). Both A & B
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When using and storing crystal microphones:
When using and storing crystal microphones:
(D). All of the above
They should be protected from:
For more info, please see Sweetwater site article on
How to Take Care of Your Microphones
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What effect does a change in the dielectric constant of a capacitor dielectric material have upon the capacitance of a capacitor:
What effect does a change in the dielectric constant of a capacitor dielectric material have upon the capacitance of a capacitor:
(A). Capacity varies directly with the dielectric constant
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Increasing the number of plates of a capacitor:
Increasing the number of plates of a capacitor:
(A). Will increase the capacitance
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If the dielectric constants of a capacitor dielectric material between the capacitor plates were changed from 1 to 1:
If the dielectric constants of a capacitor dielectric material between the capacitor plates were changed from 1 to 1:
(A). The capacitance would be twice its original value
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Contacts which slide together on opening and closing:
Contacts which slide together on opening and closing:
(D). B & C
Are known as self-wiping
Keep the contacts clean by their action
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Permanent magnets used in head telephones:
Permanent magnets used in head telephones:
(D). All of the above
Place the diaphragms under tension so that the sensitivity of the telephones will be increased
Improve the frequency response
Prevents production of second harmonics in the telephones
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Emergency repairs to an inductance coil having burned or charred insulation:
Emergency repairs to an inductance coil having burned or charred insulation:
(A). Are generally impractical, short of rewinding the coil with good wire
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Indications of a defective vacuum tube in a transmitter:
Indications of a defective vacuum tube in a transmitter:
(D). All of the above
Gas blow within the tube, excessive plate color due to overheating
No light from the filament, insufficient plate current, reduced output
Excessive plate current, possible internal arcing, fluctuating plate or grid current
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The breakdown voltage rating of a capacitor are determined by:
The breakdown voltage rating of a capacitor are determined by:
(C). A & B
The type of dielectric material used
The thickness of the dielectric material
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Crystal surfaces should be free of dirt of grease to operate properly:
Crystal surfaces should be free of dirt of grease to operate properly:
(D). All of the above
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A purplish glow from within a tube indicates:
A purplish glow from within a tube indicates:
(D). A & C
A soft tube
Air or undesired gases within the tube
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Given a solenoid with a resistance of 5 ohms and 0.34 through the winding when 1108 at 60 Hz is applied. What is the impedance?
Given a solenoid with
a resistance of 5 ohms and
0.34 through the winding when 1108
at 60 Hz is applied.
What is the impedance?
(A). 367 ohms
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Use of a low pass filter network:
Use of a low pass filter network:
(D). All of the above
Ripple filter in power supplies, harmonic suppression filters in antenna systems
Line noise filters, tone control systems
Crossover networks, output filters of detector circuits
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A special type of power supply filter choke whose inductance is inversely proportioned to values of DC within specified limits is:
A special type of power supply filter choke whose inductance is inversely proportioned to values of DC within specified limits is:
(B). Swinging choke
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The best suited material for use as an antenna strain insulator exposed to the elements:
The best suited material for use as an antenna strain insulator exposed to the elements:
(A). Glazed porcelain
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Materials frequently used for relay contacts:
(D). All of the above
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Why is rosin used as a soldering flux?
Why is rosin used as a soldering flux?
(D). All of the above
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What substance is the most widely used in crystal oscillators?
What substance is the most widely used in crystal oscillators?
(A). Quartz
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Why is an oscillator crystal operated at a constant temperature?
Why is an oscillator crystal operated at a constant temperature?
(B). To maintain a constant frequency output from the oscillator
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The advantage of a single-button carbon microphone:
The advantage of a single-button carbon microphone:
(D). All of the above
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A carbon microphone should not be:
A carbon microphone should not be:
(D). All of the above
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In connecting head telephones directly in the plate circuit of a vacuum tube one should observe the proper polarity:
In connecting head telephones directly in the plate circuit of a vacuum tube one should observe the proper polarity:
(A). To maintain maximum sensitivity in the headphones
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What should the plate current do in the operation of a Class B audio amplifier?
What should the plate current do in the operation of a Class B audio amplifier?
(A). Fluctuate
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What turns ratio does a transformer need to match a source impedance of 500 ohms to a load of 10 ohms?
What turns ratio does a transformer need to match a source impedance of 500 ohms to a load of 10 ohms?
(A). 7.1 to 1
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What microphones have a high impedance output?
(C). Any
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How may low impedance (75 ohm) head telephones be connected to the output of a vacuum tube?
How may low impedance (75 ohm) head telephones be connected to the output of a vacuum tube?
(C). Either A or B
By using an impedance matching transformer in the output stage
Connect them as a cathode bias resistor in the output stage
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Why do headphones usually have high-impedance windings?
Why do headphones usually have high-impedance windings?
(C). A & B
They can usually be operated without an impedance matching transformer
They represent a closer match to the plate load impedance for the tube delivering necessary driving power than low impedance planes
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A "choke" coil:
A "choke" coil:
(D). All of the above
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Why is correct grid bias necessary for audio frequency amplifier?
Why is correct grid bias necessary for audio frequency amplifier?
(D). All of the above
To minimize distortion
To set the operating conditions for determining the class of amplifications
So as not to exceed the rated plate dissipation of the tube
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When a tube is used as a Class B amplifier what portion of the excitation voltage cycle does plate current flow?
When a tube is used as a Class B amplifier what portion of the excitation voltage cycle does plate current flow?
(A). Slightly more than 180 degrees
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A properly operated Class A audio amplifier:
A properly operated Class A audio amplifier:
(A). Produces no serious modification of the input waveform
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What is the main advantage obtained by using two triodes in push-pull in a Class a audio frequency amplifier?
What is the main advantage obtained by using two triodes in push-pull in a Class a audio frequency amplifier?
(D). All of the above
Increased power output
Cancellation of even harmonic distortion in the output
Elimination of DC saturation, elimination of cathode by-pass capacitor
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What is the maximum permissible RMS value of audio voltage which can be applied to the grid of a Class A audio amplifier which has a grid bias of 10 V?
What is the maximum permissible RMS value of audio voltage which can be applied to the grid of a Class A audio amplifier which has a grid bias of 10 V?
(A). 7.07 V
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Distortion in a Class A amplifier can be caused by:
Distortion in a Class A amplifier can be caused by:
(D). All of the above
Insufficient plate and screen potentials, incorrect grid bias defective rube
Leaky or shorted input coupling capacitor
Excessive anokutyde if grid signal, incorrect value of load impedance
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Vacuum tubes operating as Class A amplifiers may be used as:
Vacuum tubes operating as Class A amplifiers may be used as:
(D). All of the above
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Why is a push-pull audio frequency amplifier preferable to a single-tube stage?
Why is a push-pull audio frequency amplifier preferable to a single-tube stage?
(A). When compared with a single-tube stage, power output is doubled
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What is the DC plate voltage of a resistance-coupled amplifier state with a plate-supply voltage of 260 V, a plate current of 1 mA, and a plate load resistance of 100,000 ohms?
What is the DC plate voltage of a resistance-coupled amplifier state with
a plate-supply voltage of 260 V,
a plate current of 1 mA, and
a plate load resistance of 100,000 ohms?
(A). 160 V
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Why is it necessary to use two tubes in a Class B audio amplifier?
Why is it necessary to use two tubes in a Class B audio amplifier?
(A). To prevent the excessive distortion which would result from the use of only one tube in Class B
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If the coupling capacitor leaked in a resistance-coupled audio frequency amplifier:
If the coupling capacitor leaked in a resistance-coupled audio frequency amplifier:
(D). All of the above
Excessive plate current would result
A large value of grid current would result
There would be extreme distortion, and very low gain
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A vacuum tube operated Class C audio amplifier is not feasible, either in single or push-pull:
A vacuum tube operated Class C audio amplifier is not feasible, either in single or push-pull:
(C). A & B
Since the plate current only flows 120 degrees, even in push-pull, only 2/3 of the cycle is reproduced and the resultant distortion would be unacceptable for audio
Tank circuits, which replace the missing portions of the cycle, can't be used in an audio amplifier because they only operate on one frequency
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Even harmonics may be reduced in the output of an audio frequency amplifier:
Even harmonics may be reduced in the output of an audio frequency amplifier:
(C). A & B
By operating the state push-pull
In a single tube amplifier, by operating the stage only on the linear part of the tube's characteristic curve
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The main advantage of a tuned audio frequency amplifier in a receiver used for the reception of CW:
The main advantage of a tuned audio frequency amplifier in a receiver used for the reception of CW:
(A). A reduction in interference from unwanted signals
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Decoupling networks in the plate circuit of a multistage audio amplifier:
Decoupling networks in the plate circuit of a multistage audio amplifier:
(A). Prevents oscillations from occurring in the amplifier
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An audio-transformer is seldom used as the output device in the plate circuit of a tetrode audio-amplifier stage:
An audio-transformer is seldom used as the output device in the plate circuit of a tetrode audio-amplifier stage:
(A). Because an ordinary transformer cannot supply enough impedance to the plate circuit
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The chief advantage of Class A audio operation is compared to the other classes of audio-frequency amplifiers:
The chief advantage of Class A audio operation is compared to the other classes of audio-frequency amplifiers:
(B). Low distortion of the output signal
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Which is not the principle advantage of transformer coupling compared to resistance coupling in audio-frequency amplifiers?
Which is not the principle advantage of transformer coupling compared to resistance coupling in audio-frequency amplifiers?
(D). A transformer is expensive, heavy, and bulky
Transformers are used to move electricity between coils. It can increase, decrease, or change AC to DC. When electricity moves, it creates magnetic field.
For more info, please see Wikipedia's article on Transformer, and also Inductive coupling.
Also, Elprocus site for article on What is Transformer Coupled Amplifier and Its Working
A comprehensive info on ScienceDirect site article on Coupling Transformer, which includes info on digital audio productions.
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Efficiency of a power transformer is determined by:
Efficiency of a power transformer is determined by:
(D). All of the above
For detailed info, please see Elprocus site article on What is the Efficiency of Transformer & Its Derivation
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The ratios of primary and secondary currents in a power transformer:
The ratios of primary and secondary currents in a power transformer:
(D). All of the above
For more info, please see Wikipedia's article on Transformer, and also Inductive coupling.
Also, Elprocus site for article on What is Transformer Coupled Amplifier and Its Working
A comprehensive info on ScienceDirect site article on Coupling Transformer, which includes info on digital audio productions.
For detailed info, please see Elprocus site article on What is the Efficiency of Transformer & Its Derivation
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A transformer has a primary voltage of 100, primary turns = 200, and secondary turns = 40. What is the secondary voltage?
A transformer has a
primary voltage of 100,
primary turns = 200, and
secondary turns = 40.
What is the secondary voltage?
(A). 20 V
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What factors determine the no-load voltage ratio of a power transformer?
What factors determine the no-load voltage ratio of a power transformer?
(B). Turns ratio.
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The turns ratio of a transformer varies:
The turns ratio of a transformer varies:
(A). As the square root of the impedance ratio
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Primary cells:
Primary cells:
(D). B & D
THIS IS A MISPRINT: The FCC Pool shows
D
Primary cells:
A..Can be recharged
B..Cannot be recharged
C..An attempt to recharge it would not restore the eroded electrode.
.B & D
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Secondary cells:
Secondary cells:
(D). A & C
Can be recharged
The products of the chemical change are not soluble in the electrolyte
For more info, see Wikipedia's article
History of the battery, article on
Battery nomenclature, and article
List of battery sizes
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The formation of hydrogen gas around the positive electrode of a primary cell is:
The formation of hydrogen gas around the positive electrode of a primary cell is:
(B). Polarization
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A dry cell may be tested:
A dry cell may be tested:
(D). A & C
Must be tested under normal load condition
May be taken by any conventional voltmeter
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In the usual type dry cell:
In the usual type dry cell:
(D). A & B
The negative electrode is made of zinc
The positive electrode is made of carbon
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"A", "B", and "C" batteries are alike, but specifically constructed for a particular function. Explain:
"A", "B", and "C" batteries are alike, but specifically constructed for a particular function. Explain:
(D). All of the above
The batteries in "the old days" were categorized by size and type. The A battery was the smallest, then B, C, and D. They were used for portable tube (valve) radios made before transistor radios.
The "A" type battery did power filaments, with a voltage from 1.5 Volts to 9 Volts.
The "B" type battery was used to power portable tube (valve) radios, with a from 22.5 Volts to about 90 Volts. For more info, see Medium site article What Happened to “B” Batteries?
The "C" type battery provided grid bias voltage to the control the grid. Since the tube (valve) grids did not use electric current, the grid bias voltage did not deplete the charge. For more info, please see Wikipedia's article C battery
Also, great overall info is on Wikipedia's article List of battery sizes and Vacuum tube battery
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The condition of a dry "B" battery may be determined:
The condition of a dry "B" battery may be determined:
(D). A & C
By measuring the voltage under normal load
A loss of 20 % of the voltage under normal load indicates that the battery should be replaced
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Spare "B" batteries should be stored:
(A). In a dry place
For more info, please see WikiHow site article on How to Store Batteries
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A means of comparing the weight of a volume of liquid with the same volume of distilled water:
A means of comparing the weight of a volume of liquid with the same volume of distilled water:
(A). Specific gravity
Specific gravity is the ratio of the substance as compared to the same volume of water. If a substance has a specific density of 5, it means that it is 5 times as dense as the water. A number less than 1 indicates a substance less dense than water.
For more info, please see Wikipedia's article on Relative density
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Edison type batteries:
Edison type batteries:
(D). All of the above
Have plates:
For more info, see Wikipedia's article on Nickel–iron battery
Also, see Iron Edison site article on Nickel Iron (Ni-Fe) Battery
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The electrolyte of a lead-acid storage cell:
The electrolyte of a lead-acid storage cell:
(D). B & C
For more info, see Wikipedia's article on Nickel–iron battery
Also, see Iron Edison site article on Nickel Iron (Ni-Fe) Battery
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The negative plate of a lead-acid storage cell:
The negative plate of a lead-acid storage cell:
(A). Is composed of pure spongy lead
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The positive plate of a lead-acid storage cell:
The positive plate of a lead-acid storage cell:
(B). Is composed of lead peroxide
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The chemical composition of the electrolyte in an Edison-type storage cell:
The chemical composition of the electrolyte in an Edison-type storage cell:
(D). All of the above
For more info, see Wikipedia's article on Nickel–iron battery
Also, see Iron Edison site article on Nickel Iron (Ni-Fe) Battery
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The negative plate of an Edison-type storage cell is:
The negative plate of an Edison-type storage cell is:
(A). Finely powdered pure iron
For more info, see Wikipedia's article on Nickel–iron battery
Also, see Iron Edison site article on Nickel Iron (Ni-Fe) Battery
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The positive plate of an Edison-type storage cell is:
The positive plate of an Edison-type storage cell is:
(B). Green oxide of nickel
For more info, see Wikipedia's article on Nickel–iron battery
Also, see Iron Edison site article on Nickel Iron (Ni-Fe) Battery
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The average fully-charged voltage of an Edison storage cell is:
(A). 1.2 V
For more info, see Wikipedia's article on Nickel–iron battery
Also, see Iron Edison site article on Nickel Iron (Ni-Fe) Battery
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Decrease in capacity of an Edison-type storage cell can be caused by:
Decrease in capacity of an Edison-type storage cell can be caused by:
(D). All of the above
Frequent overheating, and operating conditions over 115 degrees fahrenheit
Charging at less than the normal rate
Adding impure water to the electrolyte, or a weak or aged electrolyte
For more info, see Wikipedia's article on Nickel–iron battery
Also, see Iron Edison site article on Nickel Iron (Ni-Fe) Battery
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The average fully charged voltage of a lead-acid cell is:
(C). 2.06 V
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To increase the power output of a storage cell:
To increase the power output of a storage cell:
(A). Low internal resistance is desirable
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The condition of charge of an Edison cell can be determined:
The condition of charge of an Edison cell can be determined:
(C). Both A & B
By reading the terminal voltage under load
By checking the voltage against a standard discharge curve
For more info, see Wikipedia's article on Nickel–iron battery
Also, see Iron Edison site article on Nickel Iron (Ni-Fe) Battery
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The charge of a lead-acid storage cell:
The charge of a lead-acid storage cell:
(C). A or B
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Sulfation:
Sulfation:
(D). All of the above
The lead plates of batteries allow the accumulation of lead sulfate crystals on the surface of the plates and in surface pores. This is called "sulfation."
If there is a substantial amount of sulfate crystal accumulation, the performance of the battery is degraded.
For more info, see Crown Battery's site article on What is a Sulfated Battery and How to Prevent It
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If the polarity is reversed when charging a storage cell:
If the polarity is reversed when charging a storage cell:
(D). A & C
No damage in a lead-acid cell unless excessive
No damage in an Edison-cell if temperatures below 115 degrees Fahrenheit
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You may measure the voltage of a battery under heavy load:
You may measure the voltage of a battery under heavy load:
(A). To determine its condition of charge
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If the voltage of some cells in a battery are found to be reversed, what is indicated?
If the voltage of some cells in a battery are found to be reversed, what is indicated?
(A). Polarity was reversed while charging
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Distilled water should be added to a lead-acid storage cell:
Distilled water should be added to a lead-acid storage cell:
(D). A & B
To keep the electrolyte 1/4 inch above the to of the plates -
To keep the useful plate area sufficient to maintain the full capacity of the cell
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Local action in a lead-acid storage cell:
Local action in a lead-acid storage cell:
(D). All of the above
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To maintain a group of storage cells in good operating condition:
To maintain a group of storage cells in good operating condition:
(D). All of the above
Battery corrosion can result from:
Battery electrolyte leakage due to physical damage.
Filling up the battery with too much water.
Copper connections may cause copper sulfate to corrode battery terminal stems.
When battery is overcharged, it can result in corrosion of terminals. Also, overcharged batteries heat up and physically expand.
The useful life of battery expiration
Clean corroded terminal stems with:
Prevent corrosion by applying:
For more info, see Carcody site's article on Battery Terminal Corrosion: Why it happens & How to fix it
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What may cause the plates of a lead-acid call to buckle?
What may cause the plates of a lead-acid call to buckle?
(D). All of the above
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What may cause sulfation of a lead-acid cell?
What may cause sulfation of a lead-acid cell?
(D). All of the above
Battery corrosion can result from:
Battery electrolyte leakage due to physical damage.
Filling up the battery with too much water.
Copper connections may cause copper sulfate to corrode battery terminal stems.
When battery is overcharged, it can result in corrosion of terminals. Also, overcharged batteries heat up and physically expand.
The useful life of battery expiration
Clean corroded terminal stems with:
Prevent corrosion by applying:
For more info, see Carcody site's article on Battery Terminal Corrosion: Why it happens & How to fix it
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What may be used to neutralize an acid electrolyte?
What may be used to neutralize an acid electrolyte?
(D). All of the above
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To prevent corrosion of battery terminals:
To prevent corrosion of battery terminals:
(A). Occasionally clean and coat them with Vaseline or other suitable lubricants
Battery corrosion can result from:
Battery electrolyte leakage due to physical damage.
Filling up the battery with too much water.
Copper connections may cause copper sulfate to corrode battery terminal stems.
When battery is overcharged, it can result in corrosion of terminals. Also, overcharged batteries heat up and physically expand.
The useful life of battery expiration
Clean corroded terminal stems with:
Prevent corrosion by applying:
For more info, see Carcody site's article on Battery Terminal Corrosion: Why it happens & How to fix it
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Why should there be ventilation to the room housing a large group of storage cells?
Why should there be ventilation to the room housing a large group of storage cells?
(D). A & B
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Radio equipment on which electrolyte may be used:
Radio equipment on which electrolyte may be used:
(D). All of the above
Electrolyte:
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What is the effect of low temperature on the operation of a lead-acid storage battery?
What is the effect of low temperature on the operation of a lead-acid storage battery?
(C). A & B
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What form of energy is stored in a lead-acid storage battery?
What form of energy is stored in a lead-acid storage battery?
(A). Chemical
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How may polarity of a storage battery be determined?
How may polarity of a storage battery be determined?
(C). A & B
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A battery with a terminal voltage of 12.5 V is to be trickle-charged at a 0.5 A rate. What resistance should be connected in series with the battery to charge from a 110 V line?
A battery with a terminal voltage of 12.5 V
is to be trickle-charged at a 0.5 A rate.
What resistance should be connected in series with the battery to charge from a 110 V line?
(A). 195 ohms
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A discharged storage battery of 3 cells has an open circuit voltage of 1.8 V per cell and an internal resistance of 0.1 ohm per cell. What voltage is needed to give an initial charging rate of 10 A?
A discharged storage battery of 3 cells
has an open circuit voltage of 1.8 V per cell and
an internal resistance of 0.1 ohm per cell.
What voltage is needed to give an initial charging rate of 10 A?
(A). 8.4 V
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What capacity in amperes of storage battery is required to operate a 50 W emergency transmitter for 6 hr.? Assume a continuous transmitter load of 70% of the key-locked demand of 40 A, and an emergency light load of 1.5 A.
Assume a continuous transmitter load of 70% of the key-locked demand of 40 A,
and an emergency light load of 1.5 A.
What capacity in amperes of storage battery is required to operate a 50 W emergency transmitter for 6 hr.?
(C). A & B
A battery rated:
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If a receiver storage A battery could not be kept charged, and maintain the required watch period, what should you do?
If a receiver storage A battery could not be kept charged, and maintain the required watch period, what should you do?
(A). Increase the charging rate
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Abnormally low input power terminal voltage of a lifeboat radiotelegraph transmitter while in operation could be caused by:
Abnormally low input power terminal voltage of a lifeboat radiotelegraph transmitter while in operation could be caused by:
(D). B & C
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If a battery has 12.4 V on open circuit and 12.2 V when its charging circuit is closed:
If a battery has 12.4 V on open circuit
and 12.2 V when its charging circuit is closed:
(A). Could have polarity reversed
When charging, voltage should increase.
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The tops of lead-acid batteries should be kept dry:
The tops of lead-acid batteries should be kept dry:
(D). A & C
To prevent slow discharge of the battery
To reduce the formation of terminal corrosion
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When lead-acid cells are subject to low temperatures they should:
When lead-acid cells are subject to low temperatures they should:
(C). A & B
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If an electrolyte in a lead-acid storage cell becomes low due to evaporation:
If an electrolyte in a lead-acid storage cell becomes low due to evaporation:
(A). The level should be brought to about 1/4 inch above the tops of the plates with pure water
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An Edison storage battery should not be charged at less than the manufacturer's specified rate:
An Edison storage battery should not be charged at less than the manufacturer's specified rate:
(C). A & B
In order that the capacity of the battery shall be maximum after charge
The chemical reactions of the Edison-type cell
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Your emergency battery has a specific gravity reading of 1.120. What should be done?
Your emergency battery has a specific gravity reading of 1.120. What should be done?
(D). All of the above
Place the battery on charge at once
Bring the electrolyte level to about 1/4 inch above the top of the plates
The battery will be fully charged when the specific gravity reads 1.280 to 1.300
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What care should be taken with selecting water to add to a storage cell?
What care should be taken with selecting water to add to a storage cell?
(A). It should be chemically pure or distilled
Water is needed along with the electrolyte to take H2O and split into H and 2O when charging a lead battery. During the charging a gas is released which can ignite, so marine batteries need to be vented. Also, water is lost, requiring additional watering of the battery. Water without any other mineral elements is a must. Never use tap water, as the minerals in it will reduce the capacity of the battery and increase charging time.
For detail info, please see Progressive Dynamics, Inc.'s article on Battery Basics
Also, look at West Marine site, article on How to Select a Marine Battery
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If the circuit breakers refuse to stay closed when you place the emergency batteries on charge, what is the trouble?
If the circuit breakers refuse to stay closed when you place the emergency batteries on charge, what is the trouble?
(D). Any of the above
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Heat developed within a storage cell under charge or discharge conditions is caused by:
Heat developed within a storage cell under charge or discharge conditions is caused by:
(C). A & B
I2R losses
Energy transfer due to chemical reactions
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How would you connect a group of similar cells in a storage battery to obtain the maximum zero resistance current?
How would you connect a group of similar cells in a storage battery to obtain the maximum zero resistance current?
(A). In parallel
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How would you connect a group of similar cells in a storage battery to obtain the maximum no-bond output voltage?
How would you connect a group of similar cells in a storage battery to obtain the maximum no-bond output voltage?
(B). In series
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What current will flow in a 6 V storage battery with an internal resistance of 0.01 ohms, when a 3 W, 6 V lamp is connected?
What current will flow in a
6 V storage battery with
an internal resistance of 0.01 ohms,
when a 3 W, 6 V lamp is connected?
A. 0.4995 A
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The charging rate of a storage cell charged from a fixed voltage source decreases as the charging progresses opposition to the charging voltage?
The charging rate of a storage cell charged from a fixed voltage source decreases as the charging progresses opposition to the charging voltage?
(C). Both A & B
Because as cell voltages increase, offering more opposition to the charging voltage
When the effective charging potential is reduced, the charging current is decreased
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The principal function of the filter in a power supply:
The principal function of the filter in a power supply:
(C). Either A or B
The power supply filters even out variations in flow of electrons in Direct Current circuits. There are capacitor filters and choke filters.
For more info, please see All About Circuits site article on An Introduction to Filters
Also, see Learn About Electronics Power Supplies article on Filter Circuits.
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Advantages of capacitor input and choke-input filters when used with rectifiers:
Advantages of capacitor input and choke-input filters when used with rectifiers:
(C). A & B
Capacitor-input filter provides higher output voltage under reasonably light load conditions
Choke-input filter offers better voltage regulations
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A high-resistance fixed resistor is shunted across each unit of a high voltage series capacitor bank in the power-supply filter circuit to:
A high-resistance fixed resistor is shunted across each unit of a high voltage series capacitor bank in the power-supply filter circuit to:
(A). Insure that the correct voltage appears across each unit
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Part of the secondary winding of a transmitters power transformer is accidentally shorted. What should be the immediate effect?
Part of the secondary winding of a transmitters power transformer is accidentally shorted. What should be the immediate effect?
(A). The current would rise to an excessive value and trip the circuit breaker
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Bleeder resistors are used in power supplies:
Bleeder resistors are used in power supplies:
(C). Either A or B
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The ratio of the frequencies of the output and input circuits of a single-phase full-wave rectifier:
The ratio of the frequencies of the output and input circuits of a single-phase full-wave rectifier:
(B). 2 to 1
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A capacitor is sometimes placed in series with the primary of a power transformer:
A capacitor is sometimes placed in series with the primary of a power transformer:
(A). To improve the power factor
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What is the maximum allowable secondary voltage of a transformer used as a center-tapped full-wave rectifier with tubes having a peak inverse voltage rating of 10,000 V?
What is the maximum allowable secondary voltage of a transformer used as a center-tapped full-wave rectifier with tubes having a peak inverse voltage rating of 10,000 V?
(A). 7070 V
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If a 60 Hz transformer is connected to a 120 Hz source of the same voltage:
If a 60 Hz transformer is connected to a 120 Hz source of the same voltage:
(D). All the above
The impedance of the transformers would be greater
The current would be reduced
There would be a decrease in power delivered to the load
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If a 500 Hz transformer is connected to a 60 Hz source of the same voltage:
If a 500 Hz transformer is connected to a 60 Hz source of the same voltage:
(D). All of the above
The primary would draw excessive current
The transformer would overheat
The primary might burn out
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A 500 Hz AC plate supply, rectified by a full-wave, unfiltered rectifier circuit. What would the emission be?
A 500 Hz AC plate supply, rectified by a full-wave, unfiltered rectifier circuit. What would the emission be?
(D). All of the above
A modulated continuous wave of 500 Hz
A modulated continuous wave of 1000 Hz
A-2
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The purpose of an air gap in a filter choke coil core. Which is the incorrect answer?
The purpose of an air gap in a filter choke coil core. Which is the incorrect answer?
(A). To decrease the effective inductance for the AC component of current by increasing the DC saturation
The purpose includes:
To increase the effective inductance for the AC component of current by decreasing the DC saturation
The inductance of the coil in general's decreased
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Loose laminations in a filter choke:
Loose laminations in a filter choke:
(C). Cause a buzzing or chattering sound
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Poor regulation in a power supply may be caused by:
Poor regulation in a power supply may be caused by:
(D). All of the above
No bleeder resistance
High resistance filter chokes
Insufficient filter capacity
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Why should the case of a high-voltage transformer be grounded?
Why should the case of a high-voltage transformer be grounded?
(C). A & B
To protect personnel handling the equipment from shock
To prevent high static voltages building up between the case and grounds
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When connecting electrolytic capacitors in series:
When connecting electrolytic capacitors in series:
(A). Observe the polarity marked on the component
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Full wave rectification has ____ than half-wave:
Full wave rectification has ____ than half-wave:
(C). A and B
Better output voltage regulation
Smaller filter components for a given ripple percentage
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Voltage regulation is ____ with a high resistance choke:
Voltage regulation is ____ with a high resistance choke:
(A). Made worse
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Electrolyte capacitors are desirable over other types because:
Electrolyte capacitors are desirable over other types because:
(D). A & C
A large capacitance may be obtained with small physical dimensions
The wet-type electrolytic capacitor is "self-healing"
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The most common values of chokes range from:
The most common values of chokes range from:
(A). 5 H to 30 H
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The power transformer and rectifier of a radio receiver are designed to supply a plate voltage of 250 V when operating from a 110 V 60 Hz supply, if the transformer is connected to 110 VDC what will happen?
The power transformer and rectifier of a radio receiver are designed to supply a plate
voltage of 250 V
when operating from a
110 V 60 Hz supply,
if the transformer is connected to 110 VDC what will happen?
(D). Either A or B
The secondary would burn out
The primary would overheat and burn out
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A shunt-wound DC motor:
A shunt-wound DC motor:
(A). Has a practically constant speed under widely varying load conditions
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A series DC motor has:
A series DC motor has:
(D). All of the above
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This partially counteracts the line voltage and so limits the armature current in a DC motor:
This partially counteracts the line voltage and so limits the armature current in a DC motor:
(B). Counter EMF
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A compound-wound DC motor:
A compound-wound DC motor:
(D). A & B
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Laminated iron is used in armature and field construction to:
Laminated iron is used in armature and field construction to:
(C). A or B
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The ____ of a DC motor periodically change the armature coils to maintain one direction of rotation:
The ____ of a DC motor periodically change the armature coils to maintain one direction of rotation:
(B). Connector
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The speed of a series DC motor may increase and destroy the motor by centrifugal action:
The speed of a series DC motor may increase and destroy the motor by centrifugal action:
(A). When operated without a load
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When the field of a shunt-wound DC motor opens while the machine is operating under no load:
When the field of a shunt-wound DC motor opens while the machine is operating under no load:
(A). The motor would race, and if unchoked, might destroy itself
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____ are used in a DC motor to reduce brush sparking without moving the brushes:
____ are used in a DC motor to reduce brush sparking without moving the brushes:
(C). Either A or B
Interpoles are used in a DC motor to reduce brush sparking without moving the brushes
Commutating poles are used in a DC motor to reduce brush sparking without moving the brushes
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A short in the armature coils of a DC motor causes:
A short in the armature coils of a DC motor causes:
(C). Reduction of speed under load, and excessive armature current
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The motor-field rheostat should be ____ when starting a DC motor generator set:
The motor-field rheostat should be ____ when starting a DC motor generator set:
(B). Minimum resistance in the field circuit
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