BASIC ELECTRICITY Flashcards
1
Q
The working voltage of a capacitor in an AC circuit should be
A
at least 50% greater than the highest applied voltage
2
Q
The term that describes the combined resistive forces in an AC circuit is
A
impedance
3
Q
What is the opposition to the flow of AC produced by a magnetic field with generated back voltage (EMF) called?
A
inductive reactance
4
Q
Electrostatic fields are also known as
A
Dielectric fields
5
Q
The basis for transformer operation in the use of alternating current is mutual
A
inductance
6
Q
The opposition offered by a coil to the flow of alternating current is called (disregard resistance)
A
inductive reactance
7
Q
What factors strengthen a coil inductor?
A. Limiting and seperating the coils
B. Adding and separating the coils
C. Adding coils close together
A
C. Adding coils close together
8
Q
An increase in which of the following factors will cause an increase in the inductive reactance of a circuit?
A. inductance and frequency
B. resistance and voltage
C. resistance and capacitive reactance
A
A. inductance and frequency
9
Q
(Refer to figure 1) When different rated capacitors are connected in series in a circuit, the total capacitance is
A
less than the capacitance of the of the lowest rated capacitor
10
Q
Capacitors are sometimes used in DC circuits to
A
smooth out slight pulsations in current/voltage
11
Q
In an AC circuit, the effective voltage is
A
less than the maximum instantaneous voltage
12
Q
The amount of electricity is a capacitor can store is directly proportional to the
A
plate area and inversely proportional to the distance between the plates
13
Q
(Refer to figure 2) What is the total capacitance of a series circuit containing three capacitors with capacitance’s of .02 µF, .05 µF, .1 µF
A
.0125 µF
14
Q
What is the total capacitance of a circuit containing three capacitors in parallel with capacitances of .02 µF, .05 µF, and .1 µF?
A
.17 µF
15
Q
Convert farads to microfarads by
A
multiplying farads by 10 to the power of 6
16
Q
Convert farads to picofarads by
A
multiplying farads by 10 to the power of 12
17
Q
Unless otherwise specified, any values given for current or voltage in an AC circuit are assumed to be
A
effective values
18
Q
When different rated capacitors are connected in a parallel circuit, the total capacitance is
A
equal to the sum of all the capacitances
19
Q
When inductors are connected in series in a circuit, the total inductance is (where the magnetic fields of each inductor do not affect the others)
A
equal to the sum of the individual inductances
20
Q
(Refer to figure 3) When more than two inductors are connected together in such a way that there is no undictive coupling, the total inductance is the sum of the individual inductances.
A
less than the inductance of the lowest rated inductor
21
Q
What is the total capacitance of a parallel circuit containing three with capacitances of .25 µF, .03 µF, and .12 µF respectively?
A
.4 µF
22
Q
Which requires the most electrical power during operation?
A. A 12V motor requiring 8 amperes.
B. Four 30W lamps in a 12V parallel circuit.
C. Two lights requiring 3A each in a 24V parallel system.
A
C. Two lights requring 3A each in a 24V parallel system
23
Q
How much power must a 24V generator furnish to a system which contains the following loads?
One motor (75% efficient) 1/5hp,
Three position lights 20W each,
One heating element 5A,
One anticollision light 3A
A
451W
24
Q
A 23V electric motor has 1000W input and 1 horsepower output. Maintaining the efficiency, how much input power will a 24V, 1-hp electric motor require?
A
1000W
25
How many amperes will a 28V generator be required to supply to a circuit containing five lamps in parallel, three of which have a reisitance of 6Ω and two of which have a resistance of 5Ω each?
25.2A
26
A 1-horsepower, 24VDC electric motor that is 80% efficient requries 932.5W. How much power will a 1-horsepower, 12VDC electric motor that is 75% efficient require?
994.7 watts
27
The potential difference between two conductors which are insulated from each other is measured in
volts
28
Which effect does not apply to the movement of electrons flowing in a conductor?
A.magnetic energy.
B.thermal energy.
C.static energy.
C. static energy
29
A 24V source is required to furnish 48W to a parallel circuit consisting of four resistors of equal value. What is the voltage drop across each resistor?
24V
30
When calculating power in a reactive or inductive AC circuit, the true power is
less than the apparent power
31
(Refer to figure 4) How much power is being furnished to the circuit?
2645 watts
32
(Refer to figure 5) What is the impedance of an AC-series circuit consisting of an inductor with a reactance of 10Ω, a capacitor with a reactance of 4Ω and a reisistor with a resistance of 8Ω?
10Ω
33
(Refer to figure 6) If resistor R₅ is disconnected at the junction of R₄ and R₃ as shown, what will the ohmmeter read?
3Ω
34
(Refer to figure 7) If resistor R₃ is disconnected at terminal D, what will the ohmmeter read?
infinite resistance
35
(Refer to figure 8) With an ohmmeter connected to the circuit as shown, what will the ohmmeter read?
10Ω
36
(Refer to figure 9) How many instruments (voltmeters and ammeters) are installed correctly?
Two
37
The correct way to connect a test voltmeter in a circuit is
in parallel with a unit
38
What will a voltmeter read if properly connected across a closed switch in a circuit with electrical power on?
zero voltage
39
What does the letter Q symbolize when measuring electrical charge?
Coulombs
40
Which term means .001 ampere?
milliampere
41
A cabin entry light of 10W and a dome light of 20W are connected in parallel to a 30V source. If the voltage across the 10W light is measure, it will be
equal to the voltage across the 20W light
42
.002KV equals
2V
43
(Refer to figure 10) What is the measured voltage of the series-parallel circuit between terminals A and B?
3.0 volts
44
(Refer to figure 64) A 24V source is required to furnish 48W to a parallel circuit consisting of two resistors of equal value. What is the value of each resistor?
24Ω
45
What requires the most electrical power?
A. A 1/5hp, 24V motor which is 75% efficient.
B. Four 30W lamps arranged in a 12V parallel circuit.
C. A 24V anticollision light circuit consisting of two light assemblies which require 3 amperes each during operation.
A. A 1/5hp, 24V motor which is 75% efficient
46
What unit is used to express electrical power?
Watt
47
What is the basic unit of electrical quantity?
Coulomb. 1 coulomb = 6.28 \* 10¹⁸ electrons
48
What is operating resistance of a 30W light bulb designed for a 28V system?
26.13Ω
49
Which statement is correct when made in reference to a parallel circuit?
A. The current is equal in all portions of the circuit.
B. The total current is equal to the sum of the currents through the individual branches of the circuit.
C. The current in amperes can be found by dividing the EMF in volts by the sum of the resistors in ohms.
B. The total current is equal to the sum of the currents through the individual branches of the circuit.
50
Which of the following are commonly used as rectifiers in electrical circuits?
1. Anodes.
2. Cathodes.
3. Diodes.
3. Diodes
51
Diodes are used in electrical power supply circuits primarily as
rectifiers
52
Transfer of electric energy from one circuit to another without the aid of electrical connections
A. is called inductance.
B. is called capacitance.
C. can cause excessive arcing and heat, and as a result is practical for use only with low voltages/amperages
A. is called inductance
53
If three resistors of 3Ω, 5Ω and 22Ω are connected in series in a 28V circuit, how much curent will flow through the 3Ω resistor?
.93A
54
A circuit has an applied voltage of 30V and a load consisting of a 10Ω resistor in series with a 20Ω resistor. What is the voltage drop across the 10Ω resistor?
10V
55
(Refer to figure 11) Find the total current flowing in the wire between points C and D
3A
56
(Refer to figure 11) Find the voltage across the 8Ω resistor
24V
57
In a parallel circuit with four 6Ω resistors across a 24V battery, what is the total voltage across resistor 3 (VR3 ) in the circuit?
24V
58
If each cell, connected in series equals 2V, how would a 12 cell lead acid battery be rated?
24V
59
(Refer to figure 12) Find the total resistance of the circuit
21.2Ω
60
Which is correct in reference to electical resistance?
A. Two electrical devices will have the same combined resistance if they are connected in series as they will have if connected in parallel.
B. If one of three bulbs in a parallel lighting circuit is removed, the total resistance of the circuit will be become greater.
C. An electrical device that has a high resistance will use more power than one with a low resistance with the same applied voltage.
B. If one of three bulbs in a parallel lighting circuit is removed, the total resistance of the circuit will become greater.
61
What happens to the current in a voltage step-up transformer with a ratio of 1:4?
The current is stepped down by a 1:4 ratio.
62
(Refer to figure 13) Determine the total current flow in the circuit.
1.4A
63
In a parallel circuit with three 6Ω resistors across a 12V battery, what is the total current value in the circuit?
6A
64
(Refer to figure 14) The total resitance of the circuit is
17Ω
65
Which of these will cause the resistance of a conductor to decrease?
A. Decrease the length or the cross-sectional area.
B. Decrease the length or increase the cross-sectional area.
C. Increase the length or decrease the cross-sectional area.
B. Decrease the length or increase the cross-sectional area.
66
Through which material will magnetic lines of force pass the most readily?
Iron
67
(Refer to figure 64) A 48V source is required to furnish 192W to a parallel circuit consisting of three resistors of equal value. What is the value of each resistor?
36Ω
68
Which is correct concerning a parallel circuit?
A. Total resistance will be smaller than the smallest resistor.
B. Total resistnace will decrease when one of the resistances is removed.
C. Total voltage drop is the same as the total resistance.
A. Total resistnace will be smaller than the smallest resistor.
69
The voltage drop in a circuit of known resistance is dependent on
A. the voltage of the circuit.
B. only the resistance of the conductor and does not change with a change in either voltage or amperage.
C. the amperage of the circuit.
C. the amperage of the circuit.
70
A thermal switch, or thermal protector, as used in an electric motor, is designed to
open the circuit in order to allow cooling of the motor.
71
(Refer to figure 15) With the landing gear retracted the red indicator light will not come on if an open occurs in wire
A.#19
B.#7
C.#17
A. #19
72
(Refer to figure 15) The #7 wire is used to
close the PUSH-TO-TEST circuit
73
(Refer to figure 15) When the landing gear is down, the green light will not come on if an open occurs in wire
#6
74
(Refer to figure 16) What will be the effect if the PCO relay fails to operate when the left-hand tank is selected?
The fuel pressure crossfeed valve open light will not illuminate.
75
(Refer to figure 16) The TCO relay will operate if 24VDC is applied to the bus and the fuel tank selector is in the
crossfeed position
76
(Refer to figure 16) With power to the bus and the fuel selector switched to the right-hand tank, how many relays in the system are operating?
3
77
(Refer to figure 16) When electrical power is applied to the bus, which relays are energized?
PCC and TCC
78
(Refer to figure 16) Energize the circuit with the fuel tank selector switch selected to the left-hand position. Using the schematic, identify the switches that will change position.
5,6, 11, 12, 13, 15, 16
79
(Refer to figure 17) Which of the components is a potentiometer?
3
80
(Refer to figure 17) The electrical symbol represented at #5 is a variable
resistor
81
(Refer to figure 18) When the landing gears are up and the throttles retarded, the warning horn will not sound if an open occurs in wire.
A. 4.
B. 2.
C. 9.
A.4
82
(Refer to figure 18) The control valve switch must be places in the neutral position when the landing gears are down to
A. permit the test circuit to operate
B. prevent the warning horn from sounding when the throttles are closed
C. remove the groud from the green light
B. prevent the warning horn from sounding when the throttles are closed
83
(Refer to figure 19) Under which condition will a ground be provided for the warning horn through both gear switches when the throttles are closed?
A. Right gear up and left gear down.
B. Both gears up and the control valve out of neutral.
C. Left gear up and right gear down
C. Left gear up and right gear down
84
(Refer to figure 19) When the throttles are retarded with only the right gear down, the warning horn will not sound if an open occurs in wire
A. #5.
B. #13.
C. #6.
A. #5
85
(Refer to figure 19) When the landing gears are up and the throttles are retarded, the warning horn will not sound if an open occurs in wire
A. #5.
B. #7.
C.#6
C. #6
86
When referring to an electrical circuit diagram, what point is considered to be at zero voltage?
The ground reference
87
What is the purpose of the ground symbol used in electrical circuit diagrams?
To show that there is a return path for the current between the source of electrical energy and the load.
88
(Refer to figure 20) Troubleshooting an open circuit with a voltmeter as shown in this circuit will
A. permit current to flow and illuminate the lamp.
B. create a low resistance path and the current flow will be greater than normal.
C. permit the battery voltage to appear on the voltmeter.
permit battery voltage to appear on the voltmeter
89
(Referto figure 21) Which symbol represents a variable resistor
resistor with slanted arrow.
90
In a PNP transistor application, the solid state device is turned on when the
base is negative with respect to the emitter
91
In an NPN transistor application, the solid state device is turned on when the
base is positive with respect to the emitter
92
Typical applications for zener diodes is as
voltage regulators
93
(Refer to figure 22) Which illustration is correct concerning bias application and current (positive charge) flow
1
94
Forward biasing of a solid state device will cause the device to
conduct
95
(Refer to figure 23) If an open occurs at R₁, the light
cannot be turned off
96
(Refer to figure 23) If R₂ sticks in the up position, the light will
will be on full bright
97
(Refer to figure 24) Which statement concerning the depicted logic gate is true?
Any input being 1 will produce a 1 output
98
(Refer to figure 25) In a functional and operating circuit, the depicted logic gate's output will be 0
when one or more inputs are 0
99
(Refer to figure 26) Which of the logic gate output conditions is correct with respect to the given inputs?
2
100
Which of the following logic gates will provide an active high out only when all inputs are different? XNOR, NAND, XOR
XOR
101
A lead-acid battery with 12 cells is connected in series (no-load voltage = 2.1 volts/cell) furnishes 10 amperes to a load of 2Ω. The internal resistance of the battery in this instance is
.52Ω
102
If electrolyte from a lead-acid battery is spilled in the batery compartment, which procedure should be followed?
Apply sodium bicarbonate solution to the affected area followed by a water rinse.
103
Which statement regarding the hydrometer reading of a lead-acid storage battery electrolyte is true?
A. The hydrometer reading does not require a temperature correction if the electrolyte temperature is 80°F.
B. A specific gravity correction should be added to the hydrometer reading if the electrolyte temperature is below 59°F.
C. The hydrometer reading will give a true indication of the capacity of the battery regardless of the electrolyte temperature.
A. The hydrometer reading does not require a temperature correction if the electrolyte temperature is 80°F.
104
A fully charged lead-acid batter will not freeze until extremely low temperatures are reached because
most of the acid is in the solution
105
What determines the amound of current which will flow through a battery while it is being charged by a constant voltage source?
The state of charge of the battery
106
Which of the following statements is/are generally true regarding the charging of several aircraft batteries together?
1. Batteries of different voltages (but different capacities) can be connected in series with each other across the charger, and charged using the constant current method.
2. Batteries of different ampere-hour capacity and same voltage can be conected in parallel with each other across the charge, and charged using the constant voltage method.
3. Batteries of teh same voltage and same ampere-hour capacity must be connected in series with each other across the charger, and charged using the constant current method.
1 and 2
107
The method used to rapidly charge a nickel-cadmium battery utilizes
constant voltage and varying current
108
The purpose of providing a space underneath the pates in a lead acid battery's cell container is to
prevent sediment buildup from contacting plates and causing a short circuit
109
Which condition is an indication of improperly torqued cell link connections of a nickel-cadmium batter?
heat or burn marks on the hardware
110
The presence of any small amount of potassium carbonate deposits on the top of nickel-cadmium battery cells in service in an indication of
normal operation
111
What is the likely result of servicing and charging nickel-cadmium and lead acid batteries together in the same service area?
contamination of both types of batteries
112
Which of the following best describes the operating principal in a nickel-cadmium battery installed in an aircraft?
A. At full charge, the electrolyte will be at its lowest level and should be filled.
B. To completely charge a nickel-cadmium battery, some gassing must take place; thus, some water will be used.
C. When positive plates slowly give up oxygen, which is regained by the negative plates, the battery is charging.
To completely charge a nickel-cadmium battery, some gassing must take place; thus, some water will be used.
113
The electrolyte of a nickel cadmium battery is the lowest when the battery is
in a discharged condition
114
The electrolyte of a nickel-cadmium battery is highest when the battery is
in a fully charged condition
115
The end-of-charge voltage of a 19-cell nickel-cadmium battery, measured while still on charge,
depends upon its temperature and the method used for charging
116
Nickel cadmium batteries which are stored for along period of time will show a low liquid level because
electrolyte becomes absorbed into the plates
117
How can the state-of-charge of a nickel-cadmium battery be determined?
By a measured discharge
118
What may result if water is added to a nickel-cadmium battery when it is not fully charged?
Excessive spewing is likely to occur during the charging cycle
119
In nickel-cadmium batteries, a rise in cell temperaure
causes a decrease in internal resistance
120
Which of the following best descibes the contributing factors to thermal runaway in a nickel-cadmium battery installed in an aircraft?
A. High internal resistance intensified by high cell temperatures and a high current discharge/charge rate in a constant potential (voltage) charging system.
B. Low internal resistance intensified by high cell temperatures and a high voltage discharge/charge rate in a constant current charging system.
C. Low internal resistance intensified by high cell temperatures and a high current discharge/charge rate in a constant potential (voltage) charging system.
C. Low internal resistance intensified by high cell temperatures and a high current discharge/charge rate in a constant potential (voltage) charging system.
121
When charging current is applied to a nickel-cadmium battery, the cells emit gas
toward the end of the charging cycle
