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ELE3BE
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1992-01-26
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FCC GENERAL Exam Question Pool. Subelement 3BE.
Electrical Principles. ? Questions.
---------------------------------------------------
3BE 1.1 C
What is meant by the term impedance?
A. The electric charge stored by a capacitor
B. The opposition to the flow of AC in a circuit containing
only capacitance
C. The opposition to the flow of AC in a circuit
D. The force of repulsion presented to an electric field by
another field with the same charge
3BE 1.2 C
What is the opposition to the flow of AC in a circuit
containing both resistance and reactance called?
A. Ohm
B. Joule
C. Impedance
D. Watt
3BE 3.1 B
What is meant by the term reactance?
A. Opposition to DC caused by resistors
B. Opposition to AC caused by inductors and capacitors
C. A property of ideal resistors in AC circuits
D. A large spark produced at switch contacts when an
inductor is de-energized
3BE 3.2 D
What is the opposition to the flow of AC caused by an
inductor called?
A. Resistance
B. Reluctance
C. Admittance
D. Reactance
3BE 3.3 D
What is the opposition to the flow of AC caused by a
capacitor called?
A. Resistance
B. Reluctance
C. Admittance
D. Reactance
3BE 3.4 D
How does a coil react to AC?
A. As the frequency of the applied AC increases, the
reactance decreases
B. As the amplitude of the applied AC increases, the
reactance also increases
C. As the amplitude of the applied AC increases, the
reactance decreases
D. As the frequency of the applied AC increases, the
reactance also increases
3BE 3.5 A
How does a capacitor react to AC?
A. As the frequency of the applied AC increases, the
reactance decreases
B. As the frequency of the applied AC increases, the
reactance increases
C. As the amplitude of the applied AC increases, the
reactance also increases
D. As the amplitude of the applied AC increases, the
reactance decreases
3BE 6.1 A
When will a power source deliver maximum output?
A. When the impedance of the load is equal to the impedance of
the source
B. When the SWR has reached a maximum value
C. When the power supply fuse rating equals the primary winding
current
D. When air wound transformers are used instead of iron core
transformers
3BE 6.2 D
What is meant by impedance matching?
A. To make the load impedance much greater than the
source impedance
B. To make the load impedance much less than the source
impedance
C. To use a balun at the antenna feed point
D. To make the load impedance equal the source impedance
3BE 6.3 D
What occurs when the impedance of an electrical load is
equal to the internal impedance of the power source?
A. The source delivers minimum power to the load
B. There will be a high SWR condition
C. No current can flow through the circuit
D. The source delivers maximum power to the load
3BE 6.4 A
Why is impedance matching important in radio work?
A. So the source can deliver maximum power to the load
B. So the load will draw minimum power from the source
C. To ensure that there is less resistance than reactance
in the circuit
D. To ensure that the resistance and reactance in the
circuit are equal
3BE 7.2 B
What is the unit measurement of reactance?
A. Mho
B. Ohm
C. Ampere
D. Siemens
3BE 7.4 A
What is the unit measurement of impedance?
A. Ohm
B. Volt
C. Ampere
D. Watt
3BE 10.1 A
What is a bel?
A. The basic unit used to describe a change in power levels
B. The basic unit used to describe a change in inductances
C. The basic unit used to describe a change in capacitances
D. The basic unit used to describe a change in resistances
3BE 10.2 A
What is a decibel?
A. A unit used to describe a change in power levels,
equal to 0.1 bel
B. A unit used to describe a change in power levels,
equal to 0.01 bel
C. A unit used to describe a change in power levels,
equal to 10 bels
D. A unit used to describe a change in power levels,
equal to 100 bels
3BE 10.3 D
Under ideal conditions, a barely detectable change in loudness
is approximately how many dB?
A. 12 dB
B. 6 dB
C. 3 dB
D. 1 dB
3BE 10.4 B
A two-times increase in power results in a change of how
many dB?
A. Multiplying the original power by 2 gives a new power
that is 1 dB higher
B. Multiplying the original power by 2 gives a new power
that is 3 dB higher
C. Multiplying the original power by 2 gives a new power
that is 6 dB higher
D. Multiplying the original power by 2 gives a new power
that is 12 dB higher
3BE 10.5 D
An increase of 6 dB results from raising the power by how
many times?
A. Multiply the original power by 1.5 to get the new power
B. Multiply the original power by 2 to get the new power
C. Multiply the original power by 3 to get the new power
D. Multiply the original power by 4 to get the new power
3BE 10.6 B
A decrease of 3 dB results from lowering the power by how
many times?
A. Divide the original power by 1.5 to get the new power
B. Divide the original power by 2 to get the new power
C. Divide the original power by 3 to get the new power
D. Divide the original power by 4 to get the new power
3BE 10.7 C
A signal strength report is "10 dB over S9." If the
transmitter power is reduced from 1500 watts to 150
watts, what should be the new signal strength report?
A. S5
B. S7
C. S9
D. S9 plus 5 dB
3BE 10.8 D
A signal strength report is "20 dB over S9." If the
transmitter power is reduced from 1500 watts to 150
watts, what should be the new signal strength report?
A. S5
B. S7
C. S9
D. S9 plus 10 dB
3BE 10.9 C
A signal strength report is "20 dB over S9." If the
transmitter power is reduced from 1500 watts to 15
watts, what should be the new signal strength report?
A. S5
B. S7
C. S9
D. S9 plus 10 dB
3BE 12.1 D
If a 1.0-ampere current source is connected to two parallel-
connected 10 ohm resistors, how much current passes through
each resistor?
A. 10 amperes
B. 2 amperes
C. 1 ampere
D. 0.5 ampere
3BE 12.3 B
In a parallel circuit with a voltage source and several branch
resistors, what relationship does the total current have to the
current in the branch circuits?
A. The total current equals the average of the branch current
through each resistor
B. The total current equals the sum of the branch current through
each resistor
C The total current decreases as more parallel resistors are
added to the circuit
D. The total current is calculated by adding the voltage drops
across each resistor and multiplying the sum by the total
number of all circuit resistors
3BE 13.1 B
How many watts of electrical power are being used when a
400-VDC power source supplies an 800 ohm load?
A. 0.5 watt
B. 200 watts
C. 400 watts
D. 320,000 watts
3BE 13.2 D
How many watts of electrical power are being consumed by a
12-VDC pilot light which draws 0.2-amperes?
A. 60 watts
B. 24 watts
C. 6 watts
D. 2.4 watts
3BE 13.3 A
How many watts are being dissipated when 7.0-milliamperes
flows through 1.25 kilohms?
A. Approximately 61 milliwatts
B. Approximately 39 milliwatts
C. Approximately 11 milliwatts
D. Approximately 9 milliwatts
3BE 14.1 C
How is the total resistance calculated for several resistors
in series?
A. The total resistance must be divided by the number of
resistors to ensure accurate measurement of resistance
B. The total resistance is always the lowest-rated resistance
C. The total resistance is found by adding the individual
resistances together
D. The tolerance of each resistor must be raised proportionally
to the number of resistors
3BE 14.2 D
What is the total resistance of two equal, parallel-connected
resistors?
A. Twice the resistance of either resistance
B. The sum of the two resistances
C. The total resistance cannot be determined without
knowing the exact resistances
D. Half the resistance of either resistor
3BE 14.3 A
What is the total inductance of two equal, parallel-connected
inductors?
A. Half the inductance of either inductor, assuming no mutual
coupling
B. Twice the inductance of either inductor, assuming no mutual
coupling
C. The sum of the two inductances, assuming no mutual coupling
D. The total inductance cannot be determined without knowing
the exact inductances
3BE 14.4 B
What is the total capacitance of two equal, parallel-connected
capacitors?
A. Half the capacitance of either capacitor
B. Twice the capacitance of either capacitor
C. The value of either capacitor
D. The total capacitance cannot be determined without knowing
the exact capacitances
3BE 14.5 B
What is the total resistance of two equal, series-connected
resistors?
A. Half the resistance of either resistor
B. Twice the resistance of either resistor
C. The value of either resistor
D. The total resistance cannot be determined without knowing
the exact resistances
3BE 14.6 B
What is the total inductance of two equal, series-connected
inductors?
A. Half the inductance of either inductor, assuming no mutual
coupling
B. Twice the inductance of either inductor, assuming no mutual
coupling
C. The value of either inductor, assuming no mutual coupling
D. The total inductance cannot be determined without knowing
the exact inductances
3BE 14.7 A
What is the total capacitance of two equal, series-connected
capacitors?
A. Half the capacitance of either capacitor
B. Twice the capacitance of either capacitor
C. The value of either capacitor
D. The total capacitance cannot be determined without knowing
the exact capacitances
3BE 15.1 C
What is the voltage across a 500 turn secondary winding in a
transformer when the 2250 turn primary is connected to 117-VAC?
A. 2369 volts
B. 526.5 volts
C. 26 volts
D. 5.8 volts
3BE 15.2 A
What is the turns ratio of a transformer to match an audio
amplifier having an output impedance of 200 ohms to a speaker
having an impedance of 10 ohms?
A. 4.47 to 1
B. 14.14 to 1
C. 20 to 1
D. 400 to 1
3BE 15.3 A
What is the turns ratio of a transformer to match an audio
amplifier having an output impedance of 600 ohms to a speaker
having an impedance of 4 ohms?
A. 12.2 to 1
B. 24.4 to 1
C. 150 to 1
D. 300 to 1
3BE 15.4 D
What is the impedance of a speaker which requires a
transformer with a turns ratio of 24 to 1 to match an
audio amplifier having an output impedance of 2000 ohms?
A. 576 ohms
B. 83.3 ohms
C. 7.0 ohms
D. 3.5 ohms
3BE 16.1 B
What is the voltage that would produce the same amount of heat
over time in a resistive element as would an applied sine wave
AC voltage?
A. A DC voltage equal to the peak-to-peak value of the AC
voltage
B. A DC voltage equal to the RMS value of the AC voltage
C. A DC voltage equal to the average value of the AC voltage
D. A DC voltage equal to the peak value of the AC voltage
3BE 16.2 D
What is the peak-to-peak voltage of a sine wave which has
an RMS voltage of 117-volts?
A. 82.7 volts
B. 165.5 volts
C. 183.9 volts
D. 330.9 volts
3BE 16.3 B
A sine wave of 17-volts peak is equivalent to how many
volts RMS?
A. 8.5 volts
B. 12 volts
C. 24 volts
D. 34 volts
--------------------------------------------------
End of Subelement 3BE.