# Chapter 9 : Alternating Current Basics (Gibilisco)

20 Questions | Total Attempts: 523  Settings  • 1.
Which of the following can vary with ac, but not with dc?
• A.

Power

• B.

Voltage

• C.

Frequency

• D.

Magnitude

• 2.
On a spectrum analyzer, a pure ac signal, having just one frequency component, would look like:
• A.

A single pip

• B.

A perfect sine wave

• C.

A square wave

• D.

A sawtooth wave

• 3.
The length of time between a point in one cycle and the same point in the next cycle of an ac wave is the:
• A.

Frequency

• B.

Magnitude

• C.

Period

• D.

Polarity

• 4.
The period of an ac wave is:
• A.

The same as the frequency

• B.

Not related to the frequency

• C.

Equal to 1 divided by the frequency

• D.

Equal to amplitude divided by the frequency

• 5.
The sixth harmonic of an ac wave whose period is 0.001 second has a frequency of:
• A.

0.006Hz

• B.

167 Hz

• C.

7kHz

• D.

6kHz

• 6.
A degree of phase represents:
• A.

6.28 cycles

• B.

57.3 cycles

• C.

1/6.28 cycle

• D.

1/360 cycle

• 7.
Two waves have the same frequency but differ in phase by 1/20 cycle. The phase difference in degrees is:
• A.

18

• B.

20

• C.

36

• D.

5.73

• 8.
A triangular frequency:
• A.

Has a fast rise time and slow decay time

• B.

Has a slow rise time and fast decay time

• C.

Has equal rise and decay rates

• D.

Rises and falls abruply

• 9.
A signal has a frequency of 1770 Hz. The angular frequency is:
• A.

• B.

• C.

• D.

Impossible to determine from the data given

• 10.
Three-phase ac:
• A.

Has waves that add up to three times the originals

• B.

Has three waves, all of the same magnitude

• C.

Is what you get at a common wall outlet

• D.

Is of interest only to physicists

• 11.
If two waves have the same frequency and the same amplitude, but opposite phase, the composite wave is:
• A.

Twice the amplitude of either wave alone

• B.

Half of the amplitude of either wave alone

• C.

A xomplex waveform but with the same frequency as the originals

• D.

Zero

• 12.
If two waves have the same frequency and the same phase, the composite wave:
• A.

Has a magnitude equal to the difference between the two originals

• B.

Has a magnitude equal to the sum of the two originals

• C.

Is complex with the same frequency as the originals

• D.

Is zero

• 13.
In a 117V utility circuit, the peak voltage is:
• A.

82.7V

• B.

165V

• C.

234V

• D.

331V

• 14.
In a 117V utility circuits, the peak-to-peak voltage is:
• A.

82.7V

• B.

165V

• C.

234V

• D.

331V

• 15.
In a perfect sine wave, the pk-pk value is:
• A.

Half the peak value

• B.

The same as the peak value

• C.

1.414 times the peak value

• D.

Twice the peak value

• 16.
If a 45Vdc battery is connected in series with the 117V utility mains as shown in Fig. 9-15, the peak voltage will be:
• A.

+ 210V and - 120V

• B.

+ 162V and - 72V

• C.

+ 396V and - 286V

• D.

Both equal to 117V

• 17.
In the situation of question 16, the pk-pk voltage will be:
• A.

117 V

• B.

210 V

• C.

331 V

• D.

396 V

• 18.
Which one of the following does not affect the power output available from a particular ac generator?
• A.

The strength of the magnet

• B.

The number of turns in the coil

• C.

The type of natural energy source used.

• D.

The speed of rotation of the coil or magnet

• 19.
If a 175 V dc source were connected in series with the utility mains from a standard wall outlet, the result would be:
• A.

Smooth dc

• B.

Smooth ac

• C.

Ac with one peak greater than the other

• D.

Pulsating dc

• 20.
An advantage of ac over dc in utility applications is the fact that:
• A.

Ac is easier to transform one voltage to another.

• B.

Ac is transmitted with loss in wires

• C.

Ac can be easily gotten from dc generators

• D.

Ac can be generated with less dangerous by products

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