Chapter 9 : Alternating Current Basics (Gibilisco)
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- 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.
1770 radians per second
- B.
11,120 radians per second
- C.
282 radians per second
- 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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