Alternating Current Vs Direct Current MCQs
Practice and Learn through MCQs and Quizzes. W3Definitions.com have 40 Alternating Current Vs Direct Current MCQs
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
- Correct Answer: Option C
A sine wave has:
- A. four quadrants
- B. two alternations
- C. one period
- D. all of the above
- Correct Answer: Option D
A sine wave reaches maximum positive voltage at:
- A. 90°
- B. 0°
- C. –90°
- D. 360°
- Correct Answer: Option A
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
- Correct Answer: Option A
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
- Correct Answer: Option C
AC effective voltage is named:
- A. average
- B. peak
- C. peak-to-peak
- D. root mean square
- Correct Answer: Option D
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
- Correct Answer: Option A
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
- Correct Answer: Option B
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
- Correct Answer: Option D
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
- Correct Answer: Option D
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
- Correct Answer: Option C
If the frequency of a radio wave is increased, then its wavelength will:
- A. increase
- B. decrease
- C. remain the same
- D. cannot tell
- Correct Answer: Option B
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
- Correct Answer: Option A
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
- Correct Answer: Option D
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
- Correct Answer: Option B
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
- Correct Answer: Option A
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
- Correct Answer: Option D
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
- Correct Answer: Option C
The __________ is defined as the ratio of a pulse width (positive or negative pulse or cycle) to the overall period of time of the wave.
- A. pulse width
- B. duty cycle
- C. phase shift
- D. active ratio
- Correct Answer: Option B
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
- Correct Answer: Option C
The letter in the Greek alphabet used to represent wavelength is __________.
- A. lambda
- B. theta
- C. omega
- D. delta
- Correct Answer: Option A
The magnitude that an alternation varies from zero is called its:
- A. altitude
- B. amplitude
- C. attitude
- D. polarity
- Correct Answer: Option B
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
- Correct Answer: Option B
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
- Correct Answer: Option C
What are the two main applications for ac?
- A. direct, pulsating
- B. electric, magnetic
- C. power, information
- D. static, dynamic
- Correct Answer: Option C
What does the CRT oscilloscope display?
- A. voltage and period
- B. current and frequency
- C. rms voltage and current
- D. frequency and voltage
- Correct Answer: Option A
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
- Correct Answer: Option C
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
- Correct Answer: Option D
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
- Correct Answer: Option B
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
- Correct Answer: Option C
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
- Correct Answer: Option A
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
- Correct Answer: Option D
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
- Correct Answer: Option B
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
- Correct Answer: Option A
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
- Correct Answer: Option C
What term expresses the frequency of a rectangular wave?
- A. Hz
- B. period
- C. PRF
- D. PRT
- Correct Answer: Option C
What voltage will an ac voltmeter display?
- A. rms
- B. average
- C. peak
- D. peak-to-peak
- Correct Answer: Option A
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
- Correct Answer: Option D
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
- Correct Answer: Option D
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
- Correct Answer: Option C