WorksheetsELECS 28
Total questions: 50
Worksheet time: 25mins
What device is similar to an RTD but has a negative temperature coefficient?
Strain gauge
Thermistor
Negative-type RTD
Thermocouple
The resistive change of a strain gauge
is based on the weight placed upon it, but can be many thousands of ohms
is usually no more than 100Ω
is based on the gauge factor, but is typically less than an ohm
has a positive temperature coefficient
The silicon-controlled rectifier can be turned off
by a negative gate pulse
by forced commutation
with the off switch
when the breakover voltage is exceeded
The output voltage of a typical thermocouple is
less than 100 mV
greater than 1 V
Thermocouples vary resistance, not voltage.
None of the above
The connections to a thermocouple
can produce an unwanted thermocouple effect, which must be compensated for
produce an extra desirable thermocouple effect
must be protected, since high voltages are present
produce an extra desirable thermocouple effect and must be protected, since high voltages are present
What is the zero-voltage switch used for?
To reduce radiation of high frequencies during turn-on of a high current to a load
To control low-voltage circuits
To provide power to a circuit when power is lost
For extremely low-voltage applications
Temperature sensing can be achieved by the use of
thermocouples
RTDs
thermistors
All of the above
The purpose of compensation for a thermocouple is
to decrease temperature sensitivity
to increase voltage output
to cancel unwanted voltage output of a thermocouple
used for high-temperature circuits
The change in value of an analog signal during the conversion process produces what is called the
quantization error
resolution error
Nyquist error
sampling error
Which of the following performance specifications applies to a sample-and-hold circuit?
Aperture time
Aperture droop
Feedback
Acquisition jitter
RTDs are typically connected with other fixed resistors
in a pi configuration
in a bridge configuration
and variable resistors
and capacitors in a filter-type circuit
Holding current for an SCR is best described as
the minimum current required for turn-off
the current required before an SCR will turn on
the amount of current required to maintain conduction
the gate current required to maintain conduction
What is the moving part of a linear variable differential transformer?
Primary
Secondary
Diaphragm
Core
What are the two main applications for ac?
direct, pulsating
electric, magnetic
power, information
static, dynamic
The distance that a signal's energy can travel in the time it takes for one cycle to occur is called the signal's:
amplitude
frequency
wavelength
period
One oscilloscope selector knob that allows the major and minor divisions of the graticule to be used to determine a signal amplitude value is called the:
time/cm control
position control
intensity control
volts/cm control
If current varies periodically from zero to a maximum, back to zero, and then repeats, the signal is:
direct
alternating
pulsating
repetitive
What voltage will an ac voltmeter display?
rms
average
peak
peak-to-peak
What is the peak value of a household appliance that uses a 230 V ac source?
163 V
230 V
325 V
480 V
What is the waveform period difference between the 60 Hz electricity used in this country and the 50 Hz used in Europe?
3 ms
16 ms
4 ms
20 ms
Test equipment selection enables the technician to both generate signals and:
change circuit conditions
inject signals
sense circuit conditions
change signal frequencies
Why is ac current transfer more effective than dc current transfer over long distances?
due to the height of power lines
due to the use of ac generators
due to step-up and step-down transformers reducing I2R losses
due to very high voltages
A sine wave reaches maximum positive voltage at:
90°
0°
–90°
360°
Which percentages of full-amplitude rise time are used for a pulse wave?
0 to 50 percent
0 to 100 percent
5 to 95 percent
10 to 90 percent
What is the average value of a 12 V peak wave?
3.82 V
4.24 V
7.64 V
9.42 V
A test equipment item that has the ability to produce either square, triangular, or sawtooth waveforms is called:
a function generator
a radio frequency generator
an audio frequency generator
a frequency meter or counter
The current is flowing in what direction?
clockwise
counterclockwise
in both directions at the same time
50% of the time clockwise and 50% of the time counterclockwise
What does the CRT oscilloscope display?
voltage and period
current and frequency
rms voltage and current
frequency and voltage
Power companies supply ac, not dc, because:
it is easier to transmit ac
there is no longer a need for dc
dc is more dangerous
there are not enough batteries
If a waveform period is determined to be 10 microseconds in duration, what is the frequency of the signal?
100 Hz
1000 Hz
10 kHz
100 kHz
The phase difference between sine waves of different frequencies is:
equal to their frequency differences
the difference in their fixed time displacement
the same throughout time
constantly changing
If a sine wave signal is 100 mV peak-to-peak, how many volts would be measured by a voltmeter?
14.14 mV
35.4 mV
63.7 mV
70.7 mV
What term expresses the frequency of a rectangular wave?
Hz
period
PRF
PRT
AC effective voltage is named:
average
peak
peak-to-peak
root mean square
If a voltmeter measures a sine wave as 500 mV, what would be its average value?
159.0 mV
318.5 mV
318.5 mV
451.0 mV
One adjustable knob on the oscilloscope that allows the trace to be aligned with a reference graticule is called the:
position control
focus control
intensity control
volts/cm control
Signal comparisons may be most easily seen when using which item of test equipment?
spectrum analyzer
multimeter
function generator
dual trace oscilloscope
The magnitude that an alternation varies from zero is called its:
altitude
amplitude
attitude
polarity
The power that is distributed from a power plant to your home is:
high voltage to high voltage
low voltage to high voltage
high voltage to low voltage
low voltage to low voltage
A rectangular wave that has a duty cycle of 50 percent could be called a:
c wave
sawtooth wave
square wave
triangle wave
A triangle wave consists of repeating:
positive ramps only
negative ramps only
positive and negative ramps of equal value
positive and negative ramps of unequal value
What is the name of a device used to directly measure the frequency of a periodic wave?
oscilloscope
frequency meter or counter
audio frequency generator
radio frequency generator
Which control should be moved to display more cycles of a signal on an oscilloscope?
horizontal position to left or right
volts/cm to a smaller number
vertical position to top or bottom
time/cm to a higher setting
What is the name of a device that converts sound waves to electrical waves?
an amplifier
an antenna
a filter
a microphone
If the frequency of a radio wave is increased, then its wavelength will:
increase
decrease
remain the same
cannot tell
What is the rms voltage value of an ac signal whose peak oscilloscope display uses 3 major divisions above the zero setting? (V/cm = 5)
5.3 V
10.6 V
15.0 V
21.2 V
What is the peak-to-peak current value when an ammeter measures a 20 mA value?
14 mA
28 mA
40 mA
57 mA
How long would it take to transmit an electromagnetic wave to a receiving antenna 1,000 miles away?
5.38 ms
10.8 ms
53.8 ms
108 ms
What is the waveform period of a square wave signal that horizontally covers 3 major divisions per cycle? (time/cm = 50 ms)
50 ms
100 ms
150 ms
200 ms
What is the period of a 16 MHz sine wave?
196 ns
62.5 ns
31.25 ns
19.9 ns
