SUBELEMENT E8 -- SIGNALS AND EMISSIONS [5 Exam Questions -- 5 Groups]
E8A AC waveforms: sine wave, square
wave, sawtooth wave; AC
measurements: peak, peak-to-peak and root-mean-square (RMS) value,
peak-envelope-power (PEP) relative to average
E8A01
(C)
Starting
at a positive peak, how many times does a sine wave cross the zero axis in one
complete cycle?
A. 180 times
B. 4 times
C. 2 times
D. 360 times
E8A02
(C)
What is
a wave called that abruptly changes back and forth between two voltage levels
and remains an equal time at each level?
A. A sine wave
B. A cosine wave
C. A square wave
D. A sawtooth wave
E8A03
(D)
What
sine waves added to a fundamental frequency make up a square wave?
A. A sine wave 0.707 times the fundamental frequency
B. All odd and even harmonics
C. All even harmonics
D. All odd harmonics
E8A04
(A)
What
type of wave is made up of a sine wave of a fundamental frequency and all its
odd harmonics?
A. A square wave
B. A sine wave
C. A cosine wave
D. A tangent wave
E8A05
(B)
What is
a sawtooth wave?
A. A wave that alternates between two values
and spends an equal time at each level
B. A wave with a straight
line rise time faster than the fall time (or vice versa)
C. A wave that produces a phase angle tangent
to the unit circle
D. A wave whose amplitude at any given instant
can be represented by a point on a wheel rotating at a uniform speed
E8A06
(C)
What
type of wave has a rise time significantly faster than the fall time (or vice
versa)?
A. A cosine wave
B. A square wave
C. A sawtooth wave
D. A sine wave
E8A07
(A)
What
type of wave is made up of sine waves of a fundamental frequency and all
harmonics?
A. A sawtooth wave
B. A square wave
C. A sine wave
D. A cosine wave
E8A08
(B)
What is
the peak voltage at a common household electrical outlet?
A. 240 volts
B. 170 volts
C. 120 volts
D. 340 volts
E8A09
(C)
What is
the peak-to-peak voltage at a common household electrical outlet?
A. 240 volts
B. 120 volts
C. 340 volts
D. 170 volts
E8A10
(A)
What is
the RMS voltage at a common household electrical power outlet?
A. 120-V AC
B. 340-V AC
C. 85-V AC
D. 170-V AC
E8A11
(A)
What is
the RMS value of a 340-volt peak-to-peak pure sine wave?
A. 120-V AC
B. 170-V AC
C. 240-V AC
D. 300-V AC
E8A12
(C)
What is
the equivalent to the root-mean-square value of an AC voltage?
A. The AC voltage found by taking the square of
the average value of the peak AC voltage
B. The DC voltage causing the same heating of a
given resistor as the peak AC voltage
C. The AC voltage causing
the same heating of a given resistor as a DC voltage of the same value
D. The AC voltage found by taking the square
root of the average AC value
E8A13
(D)
What
would be the most accurate way of determining the RMS voltage of a complex
waveform?
A. By using a grid dip meter
B. By measuring the voltage with a D'Arsonval
meter
C. By using an absorption wavemeter
D. By measuring the heating
effect in a known resistor
E8A14
(A)
For
many types of voices, what is the approximate ratio of PEP to average power
during a modulation peak in a single-sideband phone signal?
A. 2.5 to 1
B. 25 to 1
C. 1 to 1
D. 100 to 1
E8A15
(B)
In a
single-sideband phone signal, what determines the PEP-to-average power ratio?
A. The frequency of the modulating signal
B. The speech
characteristics
C. The degree of carrier suppression
D. The amplifier power
E8A16
(C)
What is
the approximate DC input power to a Class B RF power amplifier stage in an
FM-phone transmitter when the PEP output power is 1500 watts?
A. 900 watts
B. 1765 watts
C. 2500 watts
D. 3000 watts
E8A17
(D)
What is
the approximate DC input power to a Class AB RF power amplifier stage in an
unmodulated carrier transmitter when the PEP output power is 500 watts?
A. 250 watts
B. 600 watts
C. 800 watts
D. 1000 watts