Jeppensen Section D Flashcards
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
Q
A
26
Q
A
27
Q
A
28
Q
A
29
Q
A
30
Q
- 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 _________
A
Inductive Reactance
31
Q
31 Inductive reactance is indicated by the symbol _______.
A
X1
32
Q
- Inductive reactance is measured in ______.
A
Ohms
33
Q
- Inductive reactance ______ (increases or decreases) as the frequency increases.
A
Increases
34
Q
- Inductive reactance may be calculated using what formula?________
A
XL = 2pifL
35
Q
- Find the inductive reactance caused by the presence of a 300-millihenry choke in a 400-hertz circuit. _______ ohms
A
753.6
36
Q
- Find the inductive reactance caused by the presence of a 1.2-henry choke in a 400-hertz circuit. _______ ohms
A
3,014.4
37
Q
- in a purely inductive circuit, the current _______ (leads or lags) the voltage,
A
lags
38
Q
- The phase angle between the current and voltage in a purely inductive circuit is _____
A
90 degrees
39
Q
- The power factor of a purely inductive circuit is _______
A
Zero
40
Q
- 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.
A
Choke
41
Q
- A(n) ______ is used to step up or step down an AC voltage.
A
Transformer
42
Q
A
43
Q
- Electrical energy is stored in a capacitor in _____ fields.
A
Electrostatic
44
Q
- The strength of an electrostatic field to determined by the _______ (voltage or current)
A
Voltage
45
Q
- A capacitor consists of two ______ separated by a(n) __________
A
Conductors
Dielectric
46
Q
- The basic unit of capacitance is the ________
A
farad
47
Q
- The three variables that affect the capacity of a capacitor are
A.
B.
C.
A
The area of the plates
The distance the plates are apart
The dielectric constant of the dielectric
48
Q
- Fifty microfarads = __________ farads
A
0.000050
49
Q
- A capacitor with a thin dielectric has _____ (more or less) capacity than the same capacitor with a thick dielectric.
A
More
50
Q
- The working voltage of a capacitor is rated in ________ (AC or DC) volts.
A
DC
51
Q
- The reference dielectric is air which has a dielectric constant of _________
A
one
52
Q
- 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).
A
parallel
53
Q
A
54
Q
A
55
Q
- What formula is used for finding the total capacitance of capacitors connected in parallel?
______________
A
CT= C1+C2+C3
56
Q
A
57
Q
- The time constant of a capacitive circuit is determined by the ______ and the _______ of the circuit.
A
Capacitance and the Resistance
58
Q
- In an R-C circuit, changes in current ________ (lead or lag) changes in the voltage.
A
Lead
59
Q
A
60
Q
- The opposition to the flow of alternating current caused by a capacitor in a circuit is known as _______.
A
Capacitive reactance
61
Q
- Capacitive reactance ________ ( increases or decreases ) as the frequency of the circuit increases.
A
Decreases
62
Q
A
63
Q
A
64
Q
- When a large amount of capacity is needed with a low working voltage, a(n) _____ ( electrolytic or non electrolytic ) capacitor is used.
A
Electrolytic
65
Q
- Three types of opposition to the flow of alternating current are
A.
B.
C.
A
Resistance
Inductive Reactance
Capacitive Reactance
66
Q
- The total opposition to the flow of alternating current is called _____.
A
Impedance
67
Q
- Total reactance is the _____ (sum of or difference between) the inductive and the capacitive reactance.
A
Difference
68
Q
A
69
Q
A
70
Q
- Power factor is the ratio of the ______ of the circuit to the impedance.
A
Resistance
71
Q
- Phase angle is the angle whose ______ (sine or cosine) is the power factor.
A
Cosine
72
Q
A
73
Q
A
74
Q
- True power may be found using the formula ________
A
Power Factor
75
Q
- True power is measured in _______ (watts or volt-amps).
A
Watts
76
Q
- Apparent power is the product of the source voltage times the ________ ________
A
Total current
77
Q
A
78
Q
A
79
Q
- What equation may be used to find the resonant frequency of an AC circuit? Resonant frequency = _______
A
FR= 1/ (2pi/LC)
80
Q
- Resonant frequency = ______ hertz
A
24.42
81
Q
- Current flow is ______(maximum or minimum) in a series RCL circuit at resonant frequency.
A
Maximum
82
Q
- Resonant frequency is ______ hertz
A
1,592
83
Q
- The source current is _______ (maximum or minimum) in a parallel RCL circuit at its resonant frequency.
A
Minimum
84
Q
- Circulating current in a parallel RCL circuit is _______(maximum or minimum) at the resonant frequency of the combination.
A
Maximum
85
Q
- Two ways of connecting the three windings of a three-phase AC generator are:
a.
b.
A
Y
Delta
86
Q
- A(n) _______ may be used to convert alternating current to direct current.
A
Rectifier
