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Experience:  MIT Graduate (Math, Programming, Science, and Music)
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# 1. The total number of AC cycles completed in one second is

### Customer Question

1. The total number of AC cycles completed in one second is the current's
A. alteration
B. timing
C. phase
D. frequency
2. What is the real power (rounded) of a balanced, three-phase, Y-connected system that has a power
factor of 0.9, an effective line current of 50 A and a phase voltage of 200 V?
A. 90 KW
B. 15.5 KW
C. 26.9 KW
D. 9 KW
3. AC power is created by using
A. an AC motor
B. Transformers
C. Batteries
D. an AC generator
4. An AC sine wave has an RMS value of 100 V. What is the average of the waveform?
A. 92.6 V
B. 102 V
C. 80 V
D. 90 V
5. If the resistance in an AC circuit is 100 OHMS and the impedance is 120 OHMS, what is the circuit's
power factor (rounded)?
A. 0.631
B. 0.833
C. 0.707
D. 0.714
6. In order to reduce inductive reactance, what devices are normally placed on transmission or distribution
lines?
A. Shunt reactors
B. Semiconductors
C. Resistors
D. Capacitors
7. The peak value of an AC sine wave is 120 V. What is the average value (rounded)?
A. 76.3 V
B. 46.8 V
C. 84.8 V
D. 25.5 V
8. If someone told you that a certain AC circuit was a capacitive circuit, you would know that in that circuit
the current
A. and voltage are zero.
B. lags the voltage.
C. and voltage are in phase.
D. leads the voltage.
9. If the phase angle in a circuit is 45 degrees, what is the power factor of this circuit?
A. 0
B. 0.15
C. 0.707
D. 0.45
10. A technician uses an oscilloscope to measure the peak value of an AC wave. He tells you that the
voltage has a peak value of 100 V. What is the rms value of the voltage?
A. 70.7 V
B. 707 V
C. 10 V
D. 100 V
11. The duration of one cycle of AC power can be divided into degrees. How many degrees are in one-half
cycle of AC power?
A. 270°
B. 180°
C. 360°
D. 90°
12. What is the phase angle of the voltage with respect to the current in a resistive circuit?
B. 0º
C. 45º lagging
13. What is the average value of an AC voltage that has a maximum peak voltage of 80 VAC?
A. 160 VAC
B. 50.88 VAC
C. 38.31 VAC
D. 56.56 VAC
14. If plotted, the voltage or current produced by an alternator forms a curve called a
A. hertz wave.
B. pulsed wave.
C. sine wave.
D. sawtooth wave.
15. The peak value of an AC sine wave is 120 V. What is the effective value (rounded)?
A. 200 V
B. 140 V
C. 65 V
D. 85 V
16. In a certain balanced three-phase system, each line current is 5 A and each line voltage is 220 V. What
is the approximate real power, if the power factor is 0.7?
A. 1770 W
B. 154 W
C. 1100 W
D. 1334 W
17. What's the time duration of one-half cycle of AC power?
A. 1/45 S
B. 1/120 S
C. 1/60 S
D. 1/30 S
18. If a sine wave representing AC voltage has an effective value of 70 VAC, what would be the wave's
peak value?
A. 63.81 V
B. 98.98 V
C. 54.96 V
D. 70.49 V
19. An AC sine wave has an effective value of 100 V. What is the peak value of the waveform?
A. 200 V
B. 96.3 V
C. 141.4 V
D. 183 V
20. An AC circuit has both a resistor and an inductor. The total opposition to the flow of current in this
circuit is called
A. impedance.
B. resistance.
C. reactance.
D. inductance.
21. When electric power is transmitted over long distances, line losses can be reduced by generating AC
rather than DC voltage, and by transmitting
A. low voltage and low current.
B. high voltage and high current.
C. high voltage and low current.
D. low voltage and high current.
22. Another name for the Y- or wye-connected system of polyphase power is the
A. split-phase system.
B. delta system.
C. star system.
D. balanced system.
23. If a motor designed for 50 or 60 cycle operation is connected to 60 Hz current, the motor will
A. overheat and fail.
B. stall easily.
C. turn faster.
D. produce less torque.
24. What is the typical frequency of AC power in North America?
A. 120 Hz
B. 400 Hz
C. 60 Hz
D. 50 Hz
25. In a three-phase power system, the phases of each voltage are normally separated by how many time
degrees?
A. 90
B. 180
C. 120
D. 60
Submitted: 1 year ago.
Category: Homework
Expert:  Martin replied 1 year ago.

Hello! What is the deadline for this work?

Expert:  Martin replied 1 year ago.

Please specify date, time and timezone. That way I'll be sure to get it done in time.