Name: ________________________ Class: ___________________ Date: __________
ID: A
MECH 1100 Quiz 4 Practice
True/False
Indicate whether the statement is true or false.
____
1. An advantage of a of a three-phase induction motor is that it does not require starter windings.
____
2. The difference in the synchronous speed of the stator field and the rotor speed of a motor is called the
differential speed.
____
3. A sychronous motor can be used when constant speed is required.
____
4. A sine wave’s frequency equals the reciprical of its period
____
5. The higher a sine waves frequency, the shorter it’s period.
____
6. A sine wave’s peak value is smaller than its RMS value.
____
7. RMS is another name for peak.
____
8. 7.07V PP is approximately equal to 2.5V RMS
____
9. The period of a 5 Hz wave form is 200ms.
____ 10. Current flows both ways simultaneously in an AC circuit.
____ 11. Only frequency increase with the speed of an AC generator.
____ 12. Kirchhoff’s voltage law can be used with resistive circuits.
____ 13. Capacitance is the ability to store voltage.
____ 14. If the distance between the plates of a capacitor increases, the capacitance decreases.
____ 15. A capacitor can fully charge in one time constant.
____ 16. Capacitance is a capacitor’s ability to store resistance.
____ 17. When two capacitors are connected in series across a dc source, the smallest capacitor drops the largest
voltage.
____ 18. A capacitor will fully charge in about five time constants.
____ 19. Efficient filtering is directly related to RC time constant.
1
Name: ________________________
ID: A
____ 20. Leakage through a capacitor is undesirable.
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____ 21. A sine wave with a frequency of 13kHz is changing at a faster rate than a sine wave with a frequency of
a. 18kHz
c. 12,000 Hz
b. 16,000 Hz
d. 1.5 MHz
____ 22. When a sine wave has a frequency of 60Hz, in 20s it goes through
a. 20 cycles
c. 1200 cycles
b. .333 cycles
d. 3 cycles
____ 23. If the peak value of a sine wave is 12V, the rms value is
a. 16.97V
c. 8.48V
b. 6V
d. 24V
____ 24. If the peak value of a sine wave is 9V, the rms value is
a. 6.36V
c. 8.24V
b. 12.72
d. 4.5V
____ 25. The average value of a 20V peak sine wave over one complete cycle is
a. 10V
c. 0V
b. 20V
d. 40V
____ 26. The average half-cycle value of a sine wave with a 10V peak is
a. 7.07V
c. 14.14V
b. 15.7V
d. 6.37V
____ 27. The instantaneous value of a 5A peak sine wave at a point 45° from its positive-going zero crossing is
a. 3.54V
c. 3.54A
b. 7.07A
d. 7.07A
____ 28. Which one of the following can be measured from points B to F?
a.
b.
the frequency
the angle
c.
d.
2
the period
the peak-to-peak voltage
Name: ________________________
ID: A
____ 29. V PP is measured between points ________ and _________.
a.
b.
A and B
G and I
c.
d.
C and H
D and F
____ 30. Which of the following can be measured from point E to point F?
a.
b.
the RMS voltage
the peak voltage
c.
d.
the peak to peak voltage
one cycle of voltage
c.
d.
6.84V P
4.84V P
____ 31. Calculate V R2
a.
b.
6.84V PP
13.15V P
3
Name: ________________________
ID: A
____ 32. What is the approximate peak input voltage?
a.
b.
28.3V P
14.1V P
c.
d.
20V P
20V P
c.
d.
13.2V P
13.7V P
____ 33. Calculate V R1
a.
b.
21.4V P
6.84V P
____ 34. What is the instantaneous voltage across R 1 at an angle of 22°?
a.
b.
8.03V
12.0V
c.
d.
4
2.56V
20.3V
Name: ________________________
ID: A
____ 35. Calculate R T
a.
b.
1.13kΩ
4.7kΩ
c.
d.
4.77kΩ
6.2kΩ
____ 36. Calculate the instantaneous voltage across R 1 at 122°
a.
b.
18.2V
5.8V
c.
d.
11.2V
11.6V
____ 37. A 60Hz sine wave completes _______ cycles every 10 seconds.
a. 6
c. 1/16
b. 10
d. 600
____ 38.
A sine wave’s instantaneous voltage is 0V at ___________degrees/
a. 0
c. 360
b. 180
d. all of these
____ 39. What is one time constant of a 4.7µF in series with a 22kΩ resister?
a. 0.103ms
c. 10.3ms
b. 1.03ms
d. 103ms
____ 40. How long will it take a 0.047µF capacitor to fully charge through a 100kΩ resister?
a. 2.35s
c. 23.5ms
b. 0.235ms
d. 235ms
____ 41. If a 4.7µF capacitor operates at 10kHz, X C =__________.
a. 339Ω
c. 3.39Ω
b. 294µΩ
d. infinite resistance
5
Name: ________________________
ID: A
____ 42. At what frequency is a 2000pF capacitor operating if its reactance is 745Ω ?
a. 107kHz
c. 1.01kHz
b. 10.1kHz
d. 1010Hz
____ 43. If a 22µF capacitor is coneected to a 15V 400Hz source, its current equals ___________.
a. 55mA
c. 829mA
b. 18.1mA
d. 1.81A
____ 44. What is the capacitance that stores 1.175µC of charge and drops 25V?
a. 0.047µF
c. 4.7µF
b. 0.47µF
d. 47µF
____ 45. How much stored charge in a 0.47µC capacitor that drops 18V?
a. 846µF
c. 8.46µF
b. 84.6µF
d. 0.846µF
____ 46. If a 0.047µF capacitor operates at 220kHz, X C equals __________.
a. 15.4k Ω
c. 150Ω
b. 1.54k Ω
d. 15.4Ω
____ 47. If a 47µF capacitor is connected to a 20V, 400Hz source, the current is __________.
a. 425A
c. 8.51A
b. 2.36A
d. 0.851A
Problem
48. Be able to define Amplitude, Cycle, Degree, Duty Cycle, Fall time, Frequency, Function generator,
Fundamental Frequency, Harmonics, Hertz, Induction motor, Instantaneous value, Oscillator, Oscilloscope,
Peak-to-Peak value, Peak value, Period, Periodic, Phase, Pulse, Pulse Width, Radian, Ramp, Rise time, rms
value, Sine Wave, Squirrel Cage, Synchronous Motor, Waveform
6
Name: ________________________
ID: A
49. Calculate V RMS , I RMS and P RMS
V RMS =___________ I RMS =_____________ P RMS = _____________
50. Interpret the oscilloscope to find V P , V PP , Period, Frequency and duty cycle.
V P =______
V PP =_______ P = ________ f = __________ Duty cycle = _______
7
Name: ________________________
ID: A
51. Know the key terms:
Bypass, Capacitance, Capacitive reactance, Capacitor, Charging, Coupling, Decoupling, Dielectric,
Dielectric Constant, Dielectric Strength, Exponential, Farad, Filter, Instantaneous power, RC time constant,
Reactive Power, Ripple Voltage, Temperature coefficient, Transient time, True Power, VAR.
52. Calculate the total capacitance, the reactants for each capacitor and the voltage drop across C 2 in RMS.
Total Capacitance = ______________ X C1 =___________
X C2 =_____________
V C2 =__________
53. Calculate the total capacitance, the reactants for each capacitor and the voltage drop across C 8 in RMS.
Total Capacitance = ________ X C8 =_______
X C9 =______
V C8 =__________
8
X C10 =______
Name: ________________________
ID: A
54. Calculate the time constant τ and the instantaneous dis-charging voltage at 1 time constant using RMS
voltage.
τ = ________ V ins tan tan eous = ________
55. Calculate the time constant τ and the instantaneous charging voltage at 1 time constant using RMS voltage.
τ = ________ V ins tan tan eous = ________
9
ID: A
MECH 1100 Quiz 4 Practice
Answer Section
TRUE/FALSE
1. ANS: T
2. ANS: F
Slip
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
PTS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
1
T
T
T
F
F
T
T
F
F
T
F
T
F
F
T
T
T
T
PTS: 1
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
1
1
1
1
1
1
PTS:
PTS:
PTS:
PTS:
1
1
1
1
MULTIPLE CHOICE
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
ANS: C
ANS: C
ANS: C
ANS: A
ANS: C
ANS: D
ANS: C
5sin(45)
PTS:
ANS:
ANS:
ANS:
ANS:
1
C
D
B
C
1
ID: A
32.
33.
34.
35.
36.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
ANS:
A
A
A
D
A
D
D
D
C
C
A
C
A
C
D
B
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
PTS:
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
PROBLEM
48. ANS:
see your book
PTS: 1
49. ANS:
V RMS = 84.84V
I RMS = 56.5mA P RMS = 4.8W
PTS: 1
50. ANS:
V P = 120V
V PP = 240V
Period = 16.3ms
f = 60 Hz Duty cycle = 36.8%
PTS: 1
51. ANS:
See your book
PTS: 1
52. ANS:
Total Capacitance = 30µF X C1 =35.36Ω X C2 =53.05Ω
V C2 =50.9V
PTS: 1
2
ID: A
53. ANS:
Total Capacitance = 127µF X C8 =132.6Ω X C9 =56.43Ω
V C8 =60V
PTS: 1
54. ANS:
τ =.000185 V ins tan tan eous = 31.21
PTS: 1
55. ANS:
τ = 4.23 V ins tan tan eous = 53.44
PTS: 1
3
X C10 =44.2Ω