# Alternating Current vs Direct Current MCQ Questions & Answers

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

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 2

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 3

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 4

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 5

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 6

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 7

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 8

A sine wave reaches maximum positive voltage at:

A. 90°
B. 0°
C. –90°
D. 360°

Question 9

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 10

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 11

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 12

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 13

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 14

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 15

A test equipment item that has the ability to produce either square, triangular, or sawtooth waveforms is called:

A. a function generator
C. an audio frequency generator
D. a frequency meter or counter

Question 16

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 17

A sine wave has:

B. two alternations
C. one period
D. all of the above

Question 18

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 19

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 20

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 21

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 22

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 23

What does the CRT oscilloscope display?

A. voltage and period
B. current and frequency
C. rms voltage and current
D. frequency and voltage

Question 24

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 25

What voltage will an ac voltmeter display?

A. rms
B. average
C. peak
D. peak-to-peak

Question 26

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 27

The magnitude that an alternation varies from zero is called its:

A. altitude
B. amplitude
C. attitude
D. polarity

Question 28

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 29

What term expresses the frequency of a rectangular wave?

A. Hz
B. period
C. PRF
D. PRT

Question 30

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

Question 31

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 32

AC effective voltage is named:

A. average
B. peak
C. peak-to-peak
D. root mean square

Question 33

What are the two main applications for ac?

A. direct, pulsating
B. electric, magnetic
C. power, information
D. static, dynamic

Question 34

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 35

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 36

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 37

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 38

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