Jeppensen Section D Flashcards
(86 cards)
1
Q
- Two advantages of alternating current over direct current are
(A)
(B)
A
It is easy to generate
It is easy to change voltage and current values
2
Q
- The waveform of alternating current produced by a rotating generator is called a _____
Wave
A
Sine
3
Q
A
4
Q
- A _____ is one complete sequence of voltage or current changes from zero to a positive peak to zero then through a negative peak, and back to zero.
A
Cycle
5
Q
- An_______ is one-half of an AC cycle.
A
Alternation
6
Q
- The time required for one cycle of events to occur is known as the ______ of alternating
current.
A
Period
7
Q
- The number of complete cycles per second is the ______ of AC and is expressed in
________.
A
Frequency
Hertz
8
Q
- The AC power used in most aircraft is ______ hertz.
A
400
9
Q
- A rotating generator having four poles and turning at 1.800 rpm will generate an AC with a frequency of _____ hertz.
A
60
10
Q
- In an AC circuit the product of the voltage and the current is the ________ and is expressed in ________
A
Apparent power
Volt-amps
11
Q
- True power in an AC circuit is expressed in terms of _______ (watts or volt-amps).
A
Watts
12
Q
- The ratio between the true power and the apparent power in an AC circuit is known as the
___________
A
Power Factor
13
Q
- The maximum value of voltage in either the positive or negative direction is known as the ________ voltage.
A
Peak
14
Q
- The maximum difference between the positive and negative peak values of alternating voltage or current is called the _______ value.
A
Peak-to-Peak
15
Q
- The average value of alternating current is calculated by multiplying _______ by the peak value.
A
0.637
16
Q
The RMS value of AC is ________ times the peak value
A
0.707
17
Q
- Another name for the RMS value of AC is the ______ value
A
effective
18
Q
- A purely resistive circuit has a power factor of _________
A
One
19
Q
- Inductance opposes a change in current by the generation of a _______
A
Back Voltage
20
Q
- The amount of induction in a coil is affected by the
a.
b.
c.
d.
e.
A
Number of turns of wire
Spacing between the turns
Number of layers of winding
Ratio of the diameter of the coil to the length
Material used for the core
21
Q
- Increasing the inductance of a coil will _______ (increase or decrease) the amount of AC that can flow
A
Decrease
22
Q
- When inductors are connected in series, the total inductance can be found using what formula? __________
A
LT=L1+L2+L3+…
23
Q
- The total inductance is millihenries.
A
230
24
Q
- When inductors are connected in parallel. the total inductance can be found using what formula?
A
LT= 1/ (1/L1+1/L2+1/L3)
25
26
27
28
29
30
30. The opposition to current flow in a conductor caused by the generation of a hack voltage as the magnetic field cuts across the conductor is called _________
Inductive Reactance
31
31 Inductive reactance is indicated by the symbol _______.
X1
32
32. Inductive reactance is measured in ______.
Ohms
33
33. Inductive reactance ______ (increases or decreases) as the frequency increases.
Increases
34
34. Inductive reactance may be calculated using what formula?________
XL = 2pifL
35
35. Find the inductive reactance caused by the presence of a 300-millihenry choke in a 400-hertz circuit. _______ ohms
753.6
36
36. Find the inductive reactance caused by the presence of a 1.2-henry choke in a 400-hertz circuit. _______ ohms
3,014.4
37
37. in a purely inductive circuit, the current _______ (leads or lags) the voltage,
lags
38
38. The phase angle between the current and voltage in a purely inductive circuit is _____
90 degrees
39
39. The power factor of a purely inductive circuit is _______
Zero
40
40. A(n) ______ is a type of inductor installed in a circuit to impede the flow of AC of a particular frequency, while not affecting the flow of AC below that frequency.
Choke
41
41. A(n) ______ is used to step up or step down an AC voltage.
Transformer
42
43
43. Electrical energy is stored in a capacitor in _____ fields.
Electrostatic
44
44. The strength of an electrostatic field to determined by the _______ (voltage or current)
Voltage
45
45. A capacitor consists of two ______ separated by a(n) __________
Conductors
Dielectric
46
46. The basic unit of capacitance is the ________
farad
47
47. The three variables that affect the capacity of a capacitor are
A.
B.
C.
The area of the plates
The distance the plates are apart
The dielectric constant of the dielectric
48
48. Fifty microfarads = __________ farads
0.000050
49
49. A capacitor with a thin dielectric has _____ (more or less) capacity than the same capacitor with a thick dielectric.
More
50
50. The working voltage of a capacitor is rated in ________ (AC or DC) volts.
DC
51
51. The reference dielectric is air which has a dielectric constant of _________
one
52
52. The formulas for finding total series capacitance are the same as those used for finding the total resistance of resistors connected in ________ (series or parallel).
parallel
53
54
55
55. What formula is used for finding the total capacitance of capacitors connected in parallel?
______________
CT= C1+C2+C3
56
57
57. The time constant of a capacitive circuit is determined by the ______ and the _______ of the circuit.
Capacitance and the Resistance
58
58. In an R-C circuit, changes in current ________ (lead or lag) changes in the voltage.
Lead
59
60
60. The opposition to the flow of alternating current caused by a capacitor in a circuit is known as _______.
Capacitive reactance
61
61. Capacitive reactance ________ ( increases or decreases ) as the frequency of the circuit increases.
Decreases
62
63
64
64. When a large amount of capacity is needed with a low working voltage, a(n) _____ ( electrolytic or non electrolytic ) capacitor is used.
Electrolytic
65
65. Three types of opposition to the flow of alternating current are
A.
B.
C.
Resistance
Inductive Reactance
Capacitive Reactance
66
66. The total opposition to the flow of alternating current is called _____.
Impedance
67
67. Total reactance is the _____ (sum of or difference between) the inductive and the capacitive reactance.
Difference
68
69
70
70. Power factor is the ratio of the ______ of the circuit to the impedance.
Resistance
71
71. Phase angle is the angle whose ______ (sine or cosine) is the power factor.
Cosine
72
73
74
74. True power may be found using the formula ________
Power Factor
75
75. True power is measured in _______ (watts or volt-amps).
Watts
76
76. Apparent power is the product of the source voltage times the ________ ________
Total current
77
78
79
79. What equation may be used to find the resonant frequency of an AC circuit? Resonant frequency = _______
FR= 1/ (2pi/LC)
80
80. Resonant frequency = ______ hertz
24.42
81
81. Current flow is ______(maximum or minimum) in a series RCL circuit at resonant frequency.
Maximum
82
82. Resonant frequency is ______ hertz
1,592
83
83. The source current is _______ (maximum or minimum) in a parallel RCL circuit at its resonant frequency.
Minimum
84
84. Circulating current in a parallel RCL circuit is _______(maximum or minimum) at the resonant frequency of the combination.
Maximum
85
85. Two ways of connecting the three windings of a three-phase AC generator are:
a.
b.
Y
Delta
86
86. A(n) _______ may be used to convert alternating current to direct current.
Rectifier
