Alternating Current vs Direct Current MCQs : This section focuses on the "Alternating Current vs Direct Current". These Multiple Choice Questions (MCQs) should be practiced to improve the Alternating Current vs Direct Current skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.
Question 1
If a sine wave signal is 100 mV peak-to-peak, how many volts would be measured by a voltmeter?
A. 14.14 mV
B. 35.4 mV
C. 63.7 mV
D. 70.7 mV
Question 2
A rectangular wave that has a duty cycle of 50 percent could be called a:
A. c wave
B. sawtooth wave
C. square wave
D. triangle wave
Question 3
AC effective voltage is named:
A. average
B. peak
C. peak-to-peak
D. root mean square
Question 4
What voltage will an ac voltmeter display?
A. rms
B. average
C. peak
D. peak-to-peak
Question 5
Which control should be moved to display more cycles of a signal on an oscilloscope?
A. horizontal position to left or right
B. volts/cm to a smaller number
C. vertical position to top or bottom
D. time/cm to a higher setting
Question 6
If a waveform period is determined to be 10 microseconds in duration, what is the frequency of the signal?
A. 100 Hz
B. 1000 Hz
C. 10 kHz
D. 100 kHz
Question 7
One adjustable knob on the oscilloscope that allows the trace to be aligned with a reference graticule is called the:
A. position control
B. focus control
C. intensity control
D. volts/cm control
Question 8
The magnitude that an alternation varies from zero is called its:
A. altitude
B. amplitude
C. attitude
D. polarity
Question 9
What is the waveform period difference between the 60 Hz electricity used in this country and the 50 Hz used in Europe?
A. 3 ms
B. 16 ms
C. 4 ms
D. 20 ms
Question 10
Test equipment selection enables the technician to both generate signals and:
A. change circuit conditions
B. inject signals
C. sense circuit conditions
D. change signal frequencies
Question 11
Which percentages of full-amplitude rise time are used for a pulse wave?
A. 0 to 50 percent
B. 0 to 100 percent
C. 5 to 95 percent
D. 10 to 90 percent
Question 12
If current varies periodically from zero to a maximum, back to zero, and then repeats, the signal is:
A. direct
B. alternating
C. pulsating
D. repetitive
Question 13
How long would it take to transmit an electromagnetic wave to a receiving antenna 1,000 miles away?
A. 5.38 ms
B. 10.8 ms
C. 53.8 ms
D. 108 ms
Question 14
The distance that a signal's energy can travel in the time it takes for one cycle to occur is called the signal's:
A. amplitude
B. frequency
C. wavelength
D. period
Question 15
What term expresses the frequency of a rectangular wave?
A. Hz
B. period
C. PRF
D. PRT
Question 16
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)
A. 5.3 V
B. 10.6 V
C. 15.0 V
D. 21.2 V
Question 17
A sine wave has:
A. four quadrants
B. two alternations
C. one period
D. all of the above
Question 18
What is the average value of a 12 V peak wave?
A. 3.82 V
B. 4.24 V
C. 7.64 V
D. 9.42 V
Question 19
If the frequency of a radio wave is increased, then its wavelength will:
A. increase
B. decrease
C. remain the same
D. cannot tell
Question 20
One oscilloscope selector knob that allows the major and minor divisions of the graticule to be used to determine a waveform period is called a:
A. focus control
B. time/cm control
C. intensity control
D. volts/cm control
Question 21
A test equipment item that has the ability to produce either square, triangular, or sawtooth waveforms is called:
A. a function generator
B. a radio frequency generator
C. an audio frequency generator
D. a frequency meter or counter
Question 22
If a voltmeter measures a sine wave as 500 mV, what would be its average value?
A. 159.0 mV
B. 318.5 mV
C. 353.5 mV
D. 451.0 mV
Question 23
What is the name of a device that converts sound waves to electrical waves?
A. an amplifier
B. an antenna
C. a filter
D. a microphone
Question 24
What is the peak-to peak voltage of a 56 Vrms ac voltage?
A. 158 V
B. 164 V
C. 82 V
D. 79 V
Question 25
Signal comparisons may be most easily seen when using which item of test equipment?
A. spectrum analyzer
B. multimeter
C. function generator
D. dual trace oscilloscope
Question 26
What is the peak-to-peak current value when an ammeter measures a 20 mA value?
A. 14 mA
B. 28 mA
C. 40 mA
D. 57 mA
Question 27
Power companies supply ac, not dc, because:
A. it is easier to transmit ac
B. there is no longer a need for dc
C. dc is more dangerous
D. there are not enough batteries
Question 28
Why is ac current transfer more effective than dc current transfer over long distances?
A. due to the height of power lines
B. due to the use of ac generators
C. due to step-up and step-down transformers reducing I2R losses
D. due to very high voltages
Question 29
A sine wave reaches maximum positive voltage at:
A. 90°
B. 0°
C. –90°
D. 360°
Question 30
A triangle wave consists of repeating:
A. positive ramps only
B. negative ramps only
C. positive and negative ramps of equal value
D. positive and negative ramps of unequal value
Question 31
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:
A. time/cm control
B. position control
C. intensity control
D. volts/cm control
Question 32
What does the CRT oscilloscope display?
A. voltage and period
B. current and frequency
C. rms voltage and current
D. frequency and voltage
Question 33
What is the waveform period of a square wave signal that horizontally covers 3 major divisions per cycle? (time/cm = 50 ms)
A. 50 ms
B. 100 ms
C. 150 ms
D. 200 ms
Question 34
The power that is distributed from a power plant to your home is:
A. high voltage to high voltage
B. low voltage to high voltage
C. high voltage to low voltage
D. low voltage to low voltage
Question 35
What is the period of a 16 MHz sine wave?
A. 196 ns
B. 62.5 ns
C. 31.25 ns
D. 19.9 ns
Question 36
The phase difference between sine waves of different frequencies is:
A. equal to their frequency differences
B. the difference in their fixed time displacement
C. the same throughout time
D. constantly changing
Question 37
What is the peak value of a household appliance that uses a 230 V ac source?
A. 163 V
B. 230 V
C. 325 V
D. 480 V
Question 38
What are the two main applications for ac?
A. direct, pulsating
B. electric, magnetic
C. power, information
D. static, dynamic
Question 39
What is the name of a device used to directly measure the frequency of a periodic wave?
A. oscilloscope
B. frequency meter or counter
C. audio frequency generator
D. radio frequency generator