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Amateur Radio 2024 - General > G5 – ELECTRICAL PRINCIPLES [3 Exam Questions – 3 Groups] 40 Questions > Flashcards

G5 – ELECTRICAL PRINCIPLES [3 Exam Questions – 3 Groups] 40 Questions Flashcards

1
Q

“What happens when inductive and capacitive reactance are equal in a series LC circuit?”

A. Resonance causes impedance to be very high
B. Impedance is equal to the geometric mean of the inductance and capacitance
C. Resonance causes impedance to be very low
D. Impedance is equal to the arithmetic mean of the inductance and capacitance

A

C. Resonance causes impedance to be very low

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2
Q

“What is reactance?”

A. Opposition to the flow of direct current caused by resistance
B. Opposition to the flow of alternating current caused by capacitance or inductance
C. Reinforcement of the flow of direct current caused by resistance
D. Reinforcement of the flow of alternating current caused by capacitance or inductance

A

B. Opposition to the flow of alternating current caused by capacitance or inductance

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3
Q

“Which of the following is opposition to the flow of alternating current in an inductor?”

A. Conductance
B. Reluctance
C. Admittance
D. Reactance

A

D. Reactance

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4
Q

“Which of the following is opposition to the flow of alternating current in a capacitor?”

A. Conductance
B. Reluctance
C. Reactance
D. Admittance

A

C. Reactance

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5
Q

“How does an inductor 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 increases
C. As the amplitude of the applied AC increases, the reactance decreases
D. As the frequency of the applied AC increases, the reactance increases

A

D. As the frequency of the applied AC increases, the reactance increases

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6
Q

“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 increases
D. As the amplitude of the applied AC increases, the reactance decreases

A

A. As the frequency of the applied AC increases, the reactance decreases

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7
Q

“What is the term for the inverse of impedance?”

A. Conductance
B. Susceptance
C. Reluctance
D. Admittance

A

D. Admittance

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8
Q

“What is impedance?”

A. The ratio of current to voltage
B. The product of current and voltage
C. The ratio of voltage to current
D. The product of current and reactance

A

C. The ratio of voltage to current

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9
Q

“What unit is used to measure reactance?”

A. Farad
B. Ohm
C. Ampere
D. Siemens

A

B. Ohm

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10
Q

“Which of the following devices can be used for impedance matching at radio frequencies?”

A. A transformer
B. A Pi-network
C. A length of transmission line
D. All these choices are correct

A

D. All these choices are correct

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11
Q

“What letter is used to represent reactance?”

A. Z
B. X
C. B
D. Y

A

B. X

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12
Q

“What occurs in an LC circuit at resonance? “

A. Current and voltage are equal
B. Resistance is cancelled
C. The circuit radiates all its energy in the form of radio waves
D. Inductive reactance and capacitive reactance cancel

A

D. Inductive reactance and capacitive reactance cancel

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13
Q

“What dB change represents a factor of two increase or decrease in power?”

A. Approximately 2 dB
B. Approximately 3 dB
C. Approximately 6 dB
D. Approximately 9 dB

A

B. Approximately 3 dB

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14
Q

“How does the total current relate to the individual currents in a circuit of parallel resistors?”

A. It equals the average of the branch currents
B. It decreases as more parallel branches are added to the circuit
C. It equals the sum of the currents through each branch
D. It is the sum of the reciprocal of each individual voltage drop

A

C. It equals the sum of the currents through each branch

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15
Q

“How many watts of electrical power are consumed if 400 VDC is supplied to an 800-ohm load?”

A. 0.5 watts
B. 200 watts
C. 400 watts
D. 3200 watts

A

B. 200 watts

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16
Q

“How many watts of electrical power are consumed by a 12 VDC light bulb that draws 0.2 amperes?”

A. 2.4 watts
B. 24 watts
C. 6 watts
D. 60 watts

A

A. 2.4 watts

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17
Q

“How many watts are consumed when a current of 7.0 milliamperes flows through a 1,250-ohm resistance?”

A. Approximately 61 milliwatts
B. Approximately 61 watts
C. Approximately 11 milliwatts
D. Approximately 11 watts

A

A. Approximately 61 milliwatts

18
Q

“What is the PEP produced by 200 volts peak-to-peak across a 50-ohm dummy load?”

A. 1.4 watts
B. 100 watts
C. 353.5 watts
D. 400 watts

A

B. 100 watts

19
Q

“What value of an AC signal produces the same power dissipation in a resistor as a DC voltage of the same value?”

A. The peak-to-peak value
B. The peak value
C. The RMS value
D. The reciprocal of the RMS value

A

C. The RMS value

20
Q

“What is the peak-to-peak voltage of a sine wave with an RMS voltage of 120 volts?”

A. 84.8 volts
B. 169.7 volts
C. 240.0 volts
D. 339.4 volts

A

D. 339.4 volts

21
Q

“What is the RMS voltage of a sine wave with a value of 17 volts peak?”

A. 8.5 volts
B. 12 volts
C. 24 volts
D. 34 volts

A

B. 12 volts

22
Q

“What percentage of power loss is equivalent to a loss of 1 dB?”

A. 10.9 percent
B. 12.2 percent
C. 20.6 percent
D. 25.9 percent

A

C. 20.6 percent

23
Q

“What is the ratio of PEP to average power for an unmodulated carrier?”

A. 0.707
B. 1.00
C. 1.414
D. 2.00

A

B. 1.00

24
Q

“What is the RMS voltage across a 50-ohm dummy load dissipating 1200 watts?”

A. 173 volts
B. 245 volts
C. 346 volts
D. 692 volts

A

B. 245 volts

25
Q

“What is the output PEP of an unmodulated carrier if the average power is 1060 watts?”

A. 530 watts
B. 1060 watts
C. 1500 watts
D. 2120 watts

A

B. 1060 watts

26
Q

“What is the output PEP of 500 volts peak-to-peak across a 50-ohm load?”

A. 8.75 watts
B. 625 watts
C. 2500 watts
D. 5000 watts

A

B. 625 watts

27
Q

“What causes a voltage to appear across the secondary winding of a transformer when an AC voltage source is connected across its primary winding?”

A. Capacitive coupling
B. Displacement current coupling
C. Mutual inductance
D. Mutual capacitance

A

C. Mutual inductance

28
Q

“What is the output voltage if an input signal is applied to the secondary winding of a 4:1 voltage step-down transformer instead of the primary winding?”

A. The input voltage is multiplied by 4
B. The input voltage is divided by 4
C. Additional resistance must be added in series with the primary to prevent overload
D. Additional resistance must be added in parallel with the secondary to prevent overload

A

A. The input voltage is multiplied by 4

29
Q

“What is the total resistance of a 10-, a 20-, and a 50-ohm resistor connected in parallel?”

A. 5.9 ohms
B. 0.17 ohms
C. 17 ohms
D. 80 ohms

A

A. 5.9 ohms

30
Q

“What is the approximate total resistance of a 100- and a 200-ohm resistor in parallel?”

A. 300 ohms
B. 150 ohms
C. 75 ohms
D. 67 ohms

A

D. 67 ohms

31
Q

“Why is the primary winding wire of a voltage step-up transformer usually a larger size than that of the secondary winding?”

A. To improve the coupling between the primary and secondary
B. To accommodate the higher current of the primary
C. To prevent parasitic oscillations due to resistive losses in the primary
D. To ensure that the volume of the primary winding is equal to the volume of the secondary winding

A

B. To accommodate the higher current of the primary

32
Q

“What is the voltage output of a transformer with a 500-turn primary and a 1500-turn secondary when 120 VAC is applied to the primary?”

A. 360 volts
B. 120 volts
C. 40 volts
D. 25.5 volts

A

A. 360 volts

33
Q

“What transformer turns ratio matches an antenna’s 600-ohm feed point impedance to a 50-ohm coaxial cable?”

A. 3.5 to 1
B. 12 to 1
C. 24 to 1
D. 144 to 1

A

A. 3.5 to 1

34
Q

“What is the equivalent capacitance of two 5.0-nanofarad capacitors and one 750-picofarad capacitor connected in parallel?”

A. 576.9 nanofarads
B. 1,733 picofarads
C. 3,583 picofarads
D. 10.750 nanofarads

A

D. 10.750 nanofarads

35
Q

“What is the capacitance of three 100-microfarad capacitors connected in series?”

A. 0.33 microfarads
B. 3.0 microfarads
C. 33.3 microfarads
D. 300 microfarads

A

C. 33.3 microfarads

36
Q

“What is the inductance of three 10-millihenry inductors connected in parallel?”

A. 0.30 henries
B. 3.3 henries
C. 3.3 millihenries
D. 30 millihenries

A

C. 3.3 millihenries

37
Q

“What is the inductance of a circuit with a 20-millihenry inductor connected in series with a 50-millihenry inductor?”

A. 7 millihenries
B. 14.3 millihenries
C. 70 millihenries
D. 1,000 millihenries

A

C. 70 millihenries

38
Q

“What is the capacitance of a 20-microfarad capacitor connected in series with a 50-microfarad capacitor?”

A. 0.07 microfarads
B. 14.3 microfarads
C. 70 microfarads
D. 1,000 microfarads

A

B. 14.3 microfarads

39
Q

“Which of the following components should be added to a capacitor to increase the capacitance?”

A. An inductor in series
B. An inductor in parallel
C. A capacitor in parallel
D. A capacitor in series

A

C. A capacitor in parallel

40
Q

“Which of the following components should be added to an inductor to increase the inductance?”

A. A capacitor in series
B. A capacitor in parallel
C. An inductor in parallel
D. An inductor in series

A

D. An inductor in series

Amateur Radio 2024 - General (10 decks)

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