SUBELEMENT G5 – ELECTRICAL PRINCIPLES

Question 1

G5A01 (C)

What is impedance?

Answer 1

C. The opposition to the flow of current in an AC circuit

Question 2

G5A02 (B)

What is reactance?

Answer 2

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

Question 3

G5A03 (D)

Which of the following causes opposition to the flow of alternating current in an inductor?

Answer 3

D. Reactance

Question 4

G5A04 (C)

Which of the following causes opposition to the flow of alternating current in a capacitor?

Answer 4

C. Reactance

Question 5

G5A05 (D)

How does an inductor react to AC?

Answer 5

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

Question 6

G5A06 (A)

How does a capacitor react to AC?

Answer 6

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

Question 7

G5A07 (D)
What happens when the impedance of an electrical load is equal to the output impedance of a power source, assuming both impedances are resistive?

Answer 7

D. The source can deliver maximum power to the load

Question 8

G5A08 (A)

Why is impedance matching important?

Answer 8

A. So the source can deliver maximum power to the load

Question 9

G5A09 (B)

What unit is used to measure reactance?

Answer 9

B. Ohm

Question 10

G5A10 (B)

What unit is used to measure impedance?

Answer 10

B. Ohm

Question 11

G5A11 (A)

Which of the following describes one method of impedance matching between two AC circuits?

Answer 11

A. Insert an LC network between the two circuits

Question 12

G5A12 (B)

What is one reason to use an impedance matching transformer?

Answer 12

B. To maximize the transfer of power

Question 13

G5A13 (D)

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

Answer 13

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

Question 14

G5B01 (B)

What dB change represents a two-times increase or decrease in power?

Answer 14

B. Approximately 3 dB

Question 15

G5B02 (C)

How does the total current relate to the individual currents in each branch of a purely resistive parallel circuit?

Answer 15

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

Question 16

G5B03 (B)

How many watts of electrical power are used if 400 VDC is supplied to an 800 ohm load?

Answer 16

B. 200 watts

Question 17

G5B04 (A)

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

Answer 17

A. 2.4 watts

Question 18

G5B05 (A)

How many watts are dissipated when a current of 7.0 milliamperes flows through 1.25 kilohms resistance?

Answer 18

A. Approximately 61 milliwatts

Question 19

G5B06 (B)
What is the output PEP from a transmitter if an oscilloscope measures 200 volts peak-to-peak across a 50 ohm dummy load connected to the transmitter output?

Answer 19

B. 100 watts

Question 20

G5B07 (C)

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

Answer 20

C. The RMS value

Question 21

G5B08 (D) ** QUESTION REMOVED BY QPC February 4, 2015**

Answer 21

NA

Question 22

G5B09 (B)

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

Answer 22

B. 12 volts

Question 23

G5B10 (C)

What percentage of power loss would result from a transmission line loss of 1 dB?

Answer 23

C. 20.5 percent

Question 24

G5B11 (B)

What is the ratio of peak envelope power to average power for an unmodulated carrier?

Answer 24

B. 1.00

Question 25

G5B12 (B) | What would be the RMS voltage across a 50 ohm dummy load dissipating 1200 watts?

Answer 25

B. 245 volts

Question 26

G5B13 (B) What is the output PEP of an unmodulated carrier if an average reading wattmeter connected to the transmitter output indicates 1060 watts?

Answer 26

B. 1060 watts

Question 27

G5B14 (B) What is the output PEP from a transmitter if an oscilloscope measures 500 volts peak-to-peak across a 50 ohm resistive load connected to the transmitter output?

Answer 27

B. 625 watts

Question 28

G5C01 (C) What causes a voltage to appear across the secondary winding of a transformer when an AC voltage source is connected across its primary winding?

Answer 28

C. Mutual inductance

Question 29

G5C02 (A) | What happens if you reverse the primary and secondary windings of a 4:1 voltage step down transformer?

Answer 29

A. The secondary voltage becomes 4 times the primary voltage

Question 30

G5C03 (B) | Which of the following components should be added to an existing resistor to increase the resistance?

Answer 30

B. A resistor in series

Question 31

G5C04 (C) | What is the total resistance of three 100 ohm resistors in parallel?

Answer 31

C. 33.3 ohms

Question 32

G5C05 (C) If three equal value resistors in series produce 450 ohms, what is the value of each resistor? A. 1500 ohms

Answer 32

C. 150 ohms

Question 33

G5C06 (C) What is the RMS voltage across a 500-turn secondary winding in a transformer if the 2250-turn primary is connected to 120 VAC?

Answer 33

C. 26.7 volts

Question 34

G5C07 (A) What is the turns ratio of a transformer used to match an audio amplifier having 600 ohm output impedance to a speaker having 4 ohm impedance?

Answer 34

A. 12.2 to 1

Question 35

G5C08 (D) What is the equivalent capacitance of two 5.0 nanofarad capacitors and one 750 picofarad capacitor connected in parallel?

Answer 35

D. 10.750 nanofarads

Question 36

G5C09 (C) | What is the capacitance of three 100 microfarad capacitors connected in series?

Answer 36

C. 33.3 microfarads

Question 37

G5C10 (C) | What is the inductance of three 10 millihenry inductors connected in parallel?

Answer 37

C. 3.3 millihenrys

Question 38

G5C11 (C) | What is the inductance of a 20 millihenry inductor connected in series with a 50 millihenry inductor?

Answer 38

C. 70 millihenrys

Question 39

G5C12 (B) | What is the capacitance of a 20 microfarad capacitor connected in series with a 50 microfarad capacitor?

Answer 39

B. 14.3 microfarads

Question 40

G5C13 (C) | Which of the following components should be added to a capacitor to increase the capacitance?

Answer 40

C. A capacitor in parallel

Question 41

G5C14 (D) | Which of the following components should be added to an inductor to increase the inductance?

Answer 41

D. An inductor in series

Question 42

G5C15 (A) | What is the total resistance of a 10 ohm, a 20 ohm, and a 50 ohm resistor connected in parallel?

Answer 42

A. 5.9 ohms

Question 43

G5C16 (B) Why is the conductor of the primary winding of many voltage step up transformers larger in diameter than the conductor of the secondary winding?

Answer 43

B. To accommodate the higher current of the primary

Question 44

G5C17 (C) | What is the value in nanofarads (nF) of a 22,000 pF capacitor?

Answer 44

C. 22 nF

Question 45

G5C18 (D) | What is the value in microfarads of a 4700 nanofarad (nF) capacitor?

Answer 45

D. 4.7 µF