# 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

What voltage will an ac voltmeter display?

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

Question 2

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 3

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 4

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 5

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 6

AC effective voltage is named:

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

Question 7

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 8

A sine wave has:

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

Question 9

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 10

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 11

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 12

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 13

What term expresses the frequency of a rectangular wave?

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

Question 14

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 15

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 16

A sine wave reaches maximum positive voltage at:

A. 90°
B. 0°
C. –90°
D. 360°

Question 17

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 18

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 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

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 21

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 22

What does the CRT oscilloscope display?

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

Question 23

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 24

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 25

What are the two main applications for ac?

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

Question 26

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 27

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 28

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 29

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 30

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 31

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 32

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 33

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 34

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 35

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

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

Question 36

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 37

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 38

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