The Decibel; current and voltage dividers; electrical power calculations; sine wave root-mean-square (RMS) values; PEP calculations

General Class Exam Question Pool

effective 7/01/2015 thru 6/30/2019

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2015-G5B: The Decibel; current and voltage dividers; electrical power calculations; sine wave root-mean-square (RMS) values; PEP calculations

2015-G5B01:
What dB change represents a two-times increase or decrease in power?

Approximately 3 dB

Approximately 2 dB

Approximately 6 dB

Approximately 12 dB

2015-G5B02:
How does the total current relate to the individual currents in each branch of a purely resistive parallel circuit?

It equals the sum of the currents through each branch

It equals the average of each branch current

It decreases as more parallel branches are added to the circuit

It is the sum of the reciprocal of each individual voltage drop

2015-G5B03:
How many watts of electrical power are used if 400 VDC is supplied to an 800 ohm load?

200 watts

0.5 watts

400 watts

3200 watts

2015-G5B04:
How many watts of electrical power are used by a 12 VDC light bulb that draws 0.2 amperes?

2.4 watts

24 watts

6 watts

60 watts

2015-G5B05:
How many watts are dissipated when a current of 7.0 milliamperes flows through 1.25 kilohms resistance?

Approximately 61 milliwatts

Approximately 61 watts

Approximately 11 milliwatts

Approximately 11 watts

2015-G5B06:
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?

100 watts

1.4 watts

353.5 watts

400 watts

2015-G5B07:
What value of an AC signal produces the same power dissipation in a resistor as a DC voltage of the same value?

The RMS value

The peak-to-peak value

The peak value

The reciprocal of the RMS value

2015-G5B09:
What is the RMS voltage of a sine wave with a value of 17 volts peak?

12 volts

8.5 volts

24 volts

34 volts

2015-G5B10:
What percentage of power loss would result from a transmission line loss of 1 dB?

20.5 percent

10.9 percent

12.2 percent

25.9 percent

2015-G5B11:
What is the ratio of peak envelope power to average power for an unmodulated carrier?

1.00

0.707

1.414

2.00

2015-G5B12:
What would be the RMS voltage across a 50 ohm dummy load dissipating 1200 watts?

245 volts

173 volts

346 volts

692 volts

2015-G5B13:
What is the output PEP of an unmodulated carrier if an average reading wattmeter connected to the transmitter output indicates 1060 watts?

1060 watts

530 watts

1500 watts

2120 watts

2015-G5B14:
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?