BASIC ELECTRICITY Flashcards
1
Q
A charged Atom is known as a(n) ____
A
Ion
2
Q
An atom having more electrons than protons will carry a positive or negative charge.
A
Negative
3
Q
An atom having fewer electrons than protons will carry a positive or negative charge.
A
Positive
4
Q
Materials which permit the flow of electrons are referred to as ________.
A
Conductors
5
Q
What are materials which oppose the movement of electrons called?
A
Insulators
6
Q
The speed of electron movement is considered to be how many miles per second?
This is the same as the speed of what?
A
186,000
light
7
Q
When electrons flow in a conductor, they cause a(n) ________________to surround the conductor.
A
Magnetic field
8
Q
Electron flow is considered to be from the ____ terminal of the battery (or other current source) through the circuit, and return to the ____terminal of the battery.
A
Negative
Positive
9
Q
The ___ is the basic unit of electrical charge (quantity) and is equal to 6.28 billion, billion electrons.
A
Coulumb
10
Q
When one coulomb of electrons flows past a point in one second, there is a current flow of one ________.
What is the symbol?
A
Ampere
I
11
Q
What is the standard unit of electrical resistance, or opposition to current flow.
What is the symbol?
A
Ohm
R
12
Q
What is the unit of electrical pressure known as?
A
Volt
13
Q
How is electrical power expressed?
What is the symbol?
A
Watts
P
14
Q
Each unit of electrical measurement may be expressed using a single letter. What letters are used for the expressions below?
1. Voltage
2. Current
3. Resistance
4. Power
A
- E
- I
- R
- P
15
Q
Write the following numbers using metric prefixes:
a. 126,000,000 ohms
b. 0.002 amp
c. 156,000 volts
d. 0.000,000,000,003 farads
e. 115,900,000 hertz
f. 326,000 meters
A
a. 126
b. 2
c. 156
d. 2
e. 115.9
f. 326
16
Q
Multiply and express your answers in scientific notation:
a. 325,000,000 x 1,500,000
b. 0.000,002 x 45
c. 750 x 0.25
A
a. 4.875 x 10(14)
b. 9 x 10 (-5)
c. 1.875 x 10(2)
17
Q
Divide using powers of ten:
a. 326,000,000 / 1,900,000
b. 365,000 / 0.025
5,400 / 18
A
a. 1.72 x 10(2)
b. 1.46 x 10(7)
c. 3 x 10(2)
18
Q
A body havine an accumulation of electrons on its surface is said to have a ____(positive or negative) static charge.
A
Negative
19
Q
Static dischargers on an aircraft control surface provide sharp points from which a static charge can be dissipated from the control surface into the ________.
A
Air
20
Q
Flexible metal braids called ______ straps connect the control surfaces to the aircraft structure to prevent the buildup of static charges.
A
Bonding
21
Q
The ease with which lines of magnetic flux can pass through a material is known as a material’s ____.
A
Permeability
22
Q
What is the opposition to the flow of magnetic force.
A
Reluctance
23
Q
One ____ is equal to a magnetic flux density of one weber per m2
A
Tesla
24
Q
One _____ represents a magnetic flux density of one maxwell per square centimeter.
A
Gauss
25
____ is the ability of a material to retain magnetism after a magnetizing force is removed.
Retentivity
26
_____ is the magnetism remaining in a material after the magnetizing force has been removed.
Residual magnetism
27
the lines of magnetic flux are considered to leave the _____ (north or south) pole of a magnet and enter at the ________ pole.
North
South
28
According to the left-hand rule, the lines of flux would encircle the conductor as shown in ____A or B?
B
29
According to the left-hand rule for electromagnets, the pole at end A of the electromagnet is the _____ pole.
North
30
The strength of an electromagnet is determined by the _\_\_ and by the _____ flowing through it.
Number of turns
Amount of current
31
What 3 things do you need to create a light?
1. Power Source
2. Conductor
3. Source
32
Which shell determines whether you have a conductor or insulator?
Outer Shell
33
What is a diode?
One-way check valve
34
What is Electron flow?
What is Conventional flow?
Negative to Positive
Positive to Negative
35
What is a coulumb and it's symbol?
Basic Unit of electric quantity
(Q)
36
What is an Amp?
What is it's symbol?
What is it also called?
1 Coulumb
(I)
Current
37
What is an Ohm?
What is it's symbol?
Measure of resistance to flow.
Ω
38
One volt results in the flow of 1 _\_\_\_?
Amp
39
What does EMF stand for?
What is the the definition of EMF?
What is the symbol for EMF?
Electromotive Force
The force to drive 1 amp to flow through 1 ohm of resistance.
(E)
40
What is the most important law to electricity?
Ohm's Law
41
What is the definition of a watt?
The amount of power dissipated when 1 amp flows under force of 1 volt.
42
What is the maximum permissible resistance for a bonding strap?
.03Ω
43
What are the 5 sources of electricity?
1. Chemical electricity - NICAD batteries
2. Thermocoupler - temperature difference causes current flow difference.
3. Light
4. Magnetrom
5. Electromagnetism
44
What is Ohm's Law?
The flow of electrons = current.
45
How many watts = 1 horsepower
746
46
Definition of horsepower
Practical measure for power in electrical circuit
47
What is Kirchhoff's Law
The sum of applied voltage and the sum of voltage drops in a closed circuit will = 0.
48
What are the 3 elements of a circuit?
1. Source
2. Load
3. Conductor
49
What 3 things affect the resistance of a conductor?
1. Physical characteristics
2. Dimensions
3. Temperature
50
What is the purpose of a conductor?
To provide a path for electrons to flow from a source through the load and back to the source with minimal resistance.
51
Definition of Resistivity
The resistance of a standard length and cross-sectional area of a conductor.
52
Most aircraft circuits use either _\_\_ or _\_\_ conductors.
1. Copper
2. Aluminum
53
Why is copper wire generally used in aircraft circuits?
It has about 2/3 the resistance of aluminum wire of the same gauge.
54
In which circuits would aluminum wire be used?
Why?
Applications requiring a great deal of current.
Aluminum weighs much less than copper
55
What is the ratio between resistance and length in a conductor?
varies directly. As length increases, its resistance increases.
56
How is the ratio between the resistance of a conductor and the cross-sectional area?
It varies inversely. As conductor's cross-sectional area increases, resistance increases.
57
How is aircraft wire measured?
American Wire Gauge (AWG)
Larger numbers represent smaller wire size.
58
What is the smallest size of wire normally used in an aircraft?
22-gauge
59
What is a circular mil?
standard measurement of a round conductor's cross-sectional area
60
What is positive temperature coefficient of resistance in metals?
The resistance of the material increases as its temperature increases.
61
Both copper and aluminum exhibit _\_\_\_ changes in resistance with temperatures encountered in flight.
small
62
Using a soft iron core in an electromagnet increases its strength because it is _\_\_\_ the lines of flux.
concentrates
63
There are 2 types of electromagnets used in practical applications, those having _\_\_\_ cores and those having _\_\_\_ cores.
fixed
movable
64
Name 5 ways electrical energy may be generated.
1. Magnetism
2. Chemical
3. Thermal
4. Pressure
5. Light
65
Formula for finding Voltage if Current and Resistance are known.
E = IR
66
Formula for finding Current if Voltage and Resistance are known.
I = E/R
67
Formula for finding Resistance if Voltage and Current are known.
R = E/I
68
Formula for finding Power if Voltage and Current are known.
P = IE
69
Formula for finding Voltage if Power and Current are known.
E = P/I
70
Formula for finding Current if Power and Voltage are known.
I = P/E
71
Formula for finding Power if Resistance and Current are known.
E = IP and P = IE or P = I = I2R
72
Formula for finding Voltage if Resistance and Power are known.
E = √PR
73
Formula for finding Current if Power and Resistance are known.
I = √P/R
74
Formula for finding Resistance if Power and Voltage are known.
I = P/E and R = E/I or R = E2/P
75
Formula for finding Resistance if Current and Power are known.
E = P/I and R = E/I or R = P/I2
76
Formula for finding Power if Voltage and Resistance are known.
I = E/R and P = IE or P = E2/R
77
If 3 amps of current are flowing in a 12-volt circuit, how much resistance is present?
4 ohms
78
When a 5 ohm resistance is placed in a 20-volt circuit, how much current will flow?
4 amps
79
A 60-watt light bulb installed in a 24-volt circuit will cause how much current to flow?
2.5 amps
80
What is the total power and total current for a 12-volt aircraft system with the following equipment installed?
a. Navigation lights, 3 lights at 20 watts each = _\_\_\_ amps
b. Radio #1, 60 watts = _\_\_\_ amps
c. Radio #2, 30 watts = _\_\_\_ amps
d. Interior lights, 30 watts = _\_\_\_ amps
Total power = _\_\_\_ watts
Total current = _\_\_\_ amps
a. 5
b. 5
c. 2.5
d. 2.5
Total power = 180 watts
Total current = 15 amps
81
How much current is required for a 12-volt DC electric motor to produce 1/4 horsepower if we assume that there are no losses in the system?
1/4 horsepower = _\_\_\_ watts
In a 12-volt motor this will require _\_\_\_ amps
186.5 watts
15.54 amps
82
The purpose of a conductor is to _\_\_\_
provide a path for electrons to flow from a source through the load and back with minimum resistance.
83
Most aircraft electrical systems are of the _\_\_\_ type, meaning aircraft structure provides _\_\_\_\_.
Why?
single-wire type
the path through which current returns to the source.
Saves a lot of weight.
84
The resistance of a conductor is affected by 3 things: _\_\_\_
1. Physical characteristics
2. Dimensions
3. Temperature
85
Copper wire has _\_\_\_ the resistance of an equivalent gauge of aluminum wire.
2/3
86
What is Resistivity?
Resistance of a standard length and cross-sectional area of a conductor.
87
For applications requiring a great deal of current, _\_\_\_/ is used.
Why?
Aluminum wire
Aluminum weighs much less than copper
88
The resistance of a conductor, the _\_\_\_ varies _\_\_\_ with the conductor's length.
The resistance of a conductor varies _\_\_\_ with it's cross-sectional area.
amount of resistance
directly
inversly
89
Aircraft wire is measured by the _\_\_\_
The smallest wire normally used in aircraft is the _\_\_\_ with a diameter of _____".
American Wire Gage (AWG) system
22-gauge
0.25"
90
Metals have a _______ meaning the resistance of the material ______ as its temperature increases.
positive temperature coefficient of resistance
increases
91
What do switches do?
Safely control the flow of electrons
92
The 2 most common switches used in aircraft are:
1. Enclosed toggle switch
2. Rocker switch
93
What is a single-pole, single-throw (SPST) switch?
What is it used for?
Switch that controls only 1 circuit and has 2 connections and 2 positions, open and closed.
To turn something on or off.
94
What is a double-pole switch used for?
To control more than 1 circuit.
95
A battery is a device which changes ______ energy to _______ energy
Chemical
Electrical
96
A primary cell _______ be recharged.
Cannot
97
The most common used storage battery in light aircraft is the _________ battery.
Lead-acid
98
The active material on the positive plate of a fully charged lead-acid battery is
Lead Peroxide
99
The active material on the negative plate of a fully charged lead-acid battery is ______
Spongy lead
100
The electrolyte of a lead-acid battery is made up of _____ _____ and water.
Sulfuric acid
101
When a lead-acid battery is discharged, the active material on both positive and negative plates is converted to _____ _____.
lead sulfate
102
The specific gravity of a fully charged lead-acid battery is approximately ______.
1.275
103
The open circuit voltage of a lead-acid battery is approximately _____ volts.
2.1
104
The capacity of a battery is its ability to produce a given amount of _____ (voltage or current) for a specified time.
current
105
The ampere-hour capacity of a lead-acid battery is determined by what 4 things?
1. Amount of active material
2. Area of plates
3. Amount of electrolytes
4. Temperature
106
The five-minute discharge rate of a lead-acid battery gives _____ (more or less) ampere-hours than the five-hour rate?
less
107
Spilled electrolyte from a lead-acid battery may be neutralized using a solution of ______ and water.
baking soda
108
When removing a battery from an aircraft, you should remove the _____ lead first.
negative
109
When installing a battery in an aircraft, you should connect the _____ lead first.
110
The constant ______ (current or voltage) charging method is the most effective method for charging aircraft batteries.
current
111
The generating system in an aircraft utilizes the constant _____ (voltage or current) method to charge a battery.
voltage
112
A nickel-cadmium battery can maintain a nearly constant _____ (voltage or current) until it is almost totally discharged.
voltage
113
High charging currents in nickel-cadmium batteries may cause a breakdown of the cellophane-like cel separator material, resulting in a condition known as _____ or _____.
vicious
thermal runaway
114
Nickel-cadmium battery installations are required to have _____ monitoring equipment.
temperature
115
Both the positive and negative plates of a nickel-cadmium cell are made of powered nickel plaque, fused to a nickel screen.
A. The positive plates are impregnated with _____ hydroxide.
B. The negative plates are impregnated with _____ hydroxide.
Nickel
Cadmium
116
The electrolyte for a nickel-cadmium battery is __________ and water.
potassium hydroxide
117
The specific gravity of the electrolyte in a nickel-cadmium battery _____ change as the state of the battery changes.
does not
118
The electrolyte level of a nickel-cadmium battery is ______ immediately after the battery is charged.
highest
119
The white powder that forms on the top of a nickel-cadmium battery that has been in service is _______.
potassium carbonate
120
During the service of a nickel-cadmium battery, the electrical leakage between the cells and the case should be checked with a ______.
milliammeter
121
If water is added to any cell of a nickel-cadmium battery, the amount and location of the cell should be recorded in the ______.
Battery Service Record
122
If the capacity of a nickel-cadmium battery is less than it should be or if there is an indication that some of the cells are unbalanced, the battery should be _______.
deep cycled
123
What is the purpose of a bonding strap?
Provides a conductive path between two structures.
124
What is the maximum permissible resistance of a bonding strap?
.003 ohms
125
The resistance of a conductor is affected by 3 things:
1. Physical characteristics
2. Dimensions
3. Temperature
126
What is a trip-free circuit breaker?
Once the breaker opens, the circuit remains open until the circuit cools regardless of the position of the operating control.
127
Using a soft iron core in an electromagnet increases its strength, those having _____ cores and those having _____ cores.
fixed
movable
128
Name 5 ways electrical energy may be generated:
1. Magnetism
2. Chemical
3. Thermal
4. Pressure
5. Light
129
What is the formula to figure Voltage when Current and Resistance are known?
E = IR
130
What is the formula to figure Current when Voltage and Resistance are known?
I = E/R
131
What is the formula to figure Resistance when Current and Voltage are known?
R = E/I
132
What is the formula to figure Power when Current and Voltage are known?
P = IE
133
What is the formula to figure Voltage when Current and Power are known?
E = P/I
134
What is the formula to figure Current when Power and Voltage are known?
I = P/E
135
What is the formula to figure Power when Current and Resistance are known?
E = IP / P = IE
136
If 3 amps of current are flowing in a 12v circuit, how much resistance is present?
4 ohms
137
When a 5 ohm resistance is placed in a 20-volt circuit, how much current will flow?
4 amps
138
A 60-watt light bulb installed in a 24-volt circuit will cause how much current flow?
2.5 amps
139
What is a rheostat?
Resistor that varies the amount of current flow. (Light dimmer switch)
140
What is a potentiometer?
Resistor that varies voltage in a circuit (Volume control audio panel)
141
What is a thermistor?
Resistor that varies based on temperature. (Fridge thermostate)
142
What are photoconductive cells?
Variable resistor that is sensitive to light (Backlighting based on ambient brightness.
143
Define Alternating Current
Current that periodically changes direction and continuously changes in magnitude.
144
Define Instantaneous Value of Alternating Current.
Value of Voltage or current flowing in any instant.
145
Define Effective Value of Alternating Current.
The direct current to produce an equal heating effect.
146
Define Maximum Value of Alternating Current.
Maximum value of largest instantaneous value.
147
Define inductance
The transfer of electrical energy without electrical connections.
148
What is the basis for transformer operations in the use of alternating current?
Mutual inductance
149
What is inductive reactance?
The opposition of a coil to the flow of alternating current.
150
An increase in inductance and frequency causes an _____ in inductive reactance.
increase
151
What is an electrostatic field?
Also known as _____
When 2 objects in close vicinity have a different electrical charge.
dielectric field
152
What determines the amount of electricity a capacitor can store?
1. Directly proportional to the plate area.
2. Inversely proportional to the distance between the plates.
153
What is the symbol for a variable capacitor?
154
A capacitor used in an ac circuit should have a working voltage value of at least _____ greater than the applied voltage to reduce or eliminate the danger of the dielectric breaking down.
50%
155
Capacitors are sometimes used in dc circuits to _____
smooth out slight pulsations in current / voltage.
156
Capacitors behave in series like resistors do in ______
parallel
157
State of charge determines ____________.....
current which will flow through a battery while being charged by a constant voltage source.
158
How are batteries rated?
according to voltage and ampere hour capacity.
159
_____ have a much lower freezing point than water in batteries.
sulfuric acid
160
A hydrometer reading does not require a temperature correction at _____.
80° F
161
Spilled electrolyte can be neutralized with _____
sodium bicaronate and rinse with water
162
how is sediment buildup that can cause a short circuit prevented.
a space is placed under the plates.
163
The voltage of batteries in series is _____
added
164
The voltage of batteries in parallel _____
remains the same
165
When a lead-acid battery is fully charged, most of the sulfuric acid is in the _____ (plates / solution)
solution
166
What determines the amount 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
167
The purpose of providing a space underneath the plates in a lead-acid battery's cell is to _______
prevent sediment buildup from contacting the plates and causing a short circuit.
168
If each cell, connected in series, equals 2 volts, how would a 12-cell lead-acid battery be rated?
24 volts
169
What is the electrolyte used in a nickel-cadmium battery?
potassium hydroxide
170
When is the electrolyte of a nickel-cadmium battery lowest?
When discharged
171
What will happen to a nicad-battery if water is added when not fully charged?
spewing will occur during charging
172
Nicad batteries which are stored for long period of time will show ______ fluid level
low
173
How do you determine the state of charge on a NICAD battery?
by a measured discharge
174
What happens if you service lead-acid batteries and NICAD batteries in the same service area?
Can result in contamination of both types of batteries because fumes are not compatible with each.
175
What are the methods of charging batteries?
1. Constant voltage - charging airborne
2. Constant current method
176
What is the advantage of a constant voltage method of charging?
Rapid charging rate
177
What are the disadvantages of a constant voltage method?
1. High charging rate could cause the battery to overheat.
178
What is the advantage of a constant current method of charging?
controls the charging rate
179
What is the disadvantage of a constant current method of charging?
lower rate of charge
180
When charging multiple batteries what applies to the constant voltage method?
1. Must be connected in parallel
2. Can be different capacity but must be same voltage
181
When charging multiple batteries what applies to the constant current method?
1. Must be connected in series
2. Can be different voltage but must be same capacity.
182
When do NICAD batteries tend to emit gas?
toward the end of the charging cycle
183
What determines the voltage of a fully charged NICAD 19 cell battery?
depends on the temperature & method used for charging.
184
When do NICAD batteries tend to heat up?
when current moves either in to or out of them
185
NICAD batteries have _____ internal resistance allowing a high rate of charging current
low
186
High temperatures in a NICAD batteries cause the separating material inside the cells to break down which reduces the _____ _____ allowing more current flow causing more heat.
This process is called ______
internal resistance
thermal runaway
187
What contributes to thermal runaway
1. Low internal resistance
2. High cell temperatures
3. High current discharge / charge rate
188
Heat or burn on the hardware is an indication of _____
an indication of improperly torqued cell link connections
189
What is the most probably cause of excessive amount of potassium carbonate formation?
battery overcharging
190
NICAD battery cases and drain surfaces which have been affected by electrolyte should be neutralized with _____
boric acid
191
If electrolyte from a lead-acid battery is spilled in the battery compartment, which procedure should be followed?
apply sodium bicarbonate solution to the affected area followed by a water rinse.
192
The method used to rapidly charge a nickel-cadmium battery utilizes _____
constant voltage and varying current
193
What condition is an indication of improperly torqued cell link connections of a nickel-cadmium battery?
Heat or burn marks on the hardware
194
The presence of small amounts of potassium carbonate deposits on the top of nickel-cadmium battery cells that have been in service for a time is an indication of _____
normal operation
195
What is the likely result of servicing and charging nickel-cadmium and lead-acid batteries together in the same service are?
contamination of both types of batteries
196
The electrolyte of a nickel-cadmium battery is highest when the battery is _____
in fully charged condition
197
The end of charge voltage of a 19-cell nickel-cadmium battery, measured while still on a charge ______
depends upon its temperature and the method used for charging
198
Nicad batteries which are stored for a long period of time will show a low liquid level because ______
electrolyte becomes absorbed in the plates
199
How can the state-of-charge of a Nicad battery be determined?
By a measured discharge
200
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
201
In Nicad batteries, a rise in cell temperature
causes a decrease in internal resistance
202
When a charging current is applied to a nickel-cadmium battery, the cells emit gas only _____
towards the end of the charging cycle
203
Nicad battery cases and drain surfaces which have been affected by electrolyte should be neutralized with a solution of _____
boric acid
204
What best describes the contributing factors to thermal runaway in a Nicad battery installed in an aircraft?
1. Low internal resistance intensisified by high cell temperatures.
2. High current discharge / charge rate in a constant potential (voltage) charging system.
205
How do you use an ohm meter to correctly test for resistance?
1. Put ohm meter parallel to the resistance.
2. Must have 1 end of the circuit open
206
What is the correct way to connect an ammeter to test
1. The ammeter should be in series with the circuit
2. Avoid creating an unintended 2nd path for the current.
207
How do you connect a voltmeter to test a circuit?
1. Connect it parallel to the circuit
2. Verify the polarity of the voltmeter is correct.
208
If an ammeter show a full charge rate, but the battery remains discharged what is the likely cause?
an internally shorted battery
209
What is the purpose of the ground symbol used in electrical circuit diagrams?
shows a return path for fault currents and allows the fuse or breaker to disconnect the circuit.
210
When referring to an electrical circuit diagram, what point is considered to be at zero voltage?
ground reference
211
212
What does a bonding strap do?
provides a low-resistance path between a control surface and the aircraft structure.
213
What is the symbol for Electrical Charge?
What is the unit?
Q
Coulumb
214
What is the symbol for Electromotive force?
What is the unit?
E or V
Volt
215
What is the symbol for Current?
What is the unit?
I
Ampere
216
What is the symbol for Resistance?
What is the unit?
R
Ohm
217
What is the symbol for Power?
What is the unit?
P
Watt
218
MULTIPLIER. PREFIX. SYMBOL
1,000,000 _____ _____
1,000
100
.001
0.000,001
0,000,000,001
0,000,000,000,001
MULTIPLIER. PREFIX. SYMBOL
1,000,000 Mega M
1,000. Kilo k
100 hecto h
.001 milli m
0.000,001. micro (mu)
0,000,000,001 nano n
0,000,000,000,001 pico p
219
With left-hand rule of thumb for electron flow. If you grasp the conductor in your left hand with your thumb pointing in the direction of electron flow, your fingers encircle the conductor in the direction of the ______________.
lines of flux travel
220
With left-hand rule of thumb for coils. If you grasp the conductor in your left hand with your thumb point in the direction of electron flow, your thumb points to the ______________.
north pole
221
Definition of ohm's law
current that flows in a circuit is:
- directly proportional to the voltage (force) that causes it
- inversely proportional to the resistance (opposition).
222
1 horsepower = ______ watts
746
223
Protective devices (circuit breakers / fuses) prevent damage caused by ______ resulting in large amounts of ______ or a _____ resulting in _____.
overloading
current flow
short
conductor heating
224
overloading a circuit results from _____
loads that are too large for the wiring
225
A short occurs when _____
part of a circuit comes in direct contact with return side of the circuit.
226
A trip-free circuit breaker means
once the breaker opens, the circuit remains open until the circuit cools regardless of position of the operating control.
Impossible to hold circuit closed if fault exists.
227
Resistor color codes:
First band - _____
Second Band - _____
Third Band - _____
Fourth Band - _____
No 4th band color - _____
1. First figure
2. 2nd figure
3. multiplier
4. tolerance
5. 20% tolerance
228
A battery converts ________ into _________
chemical energy
electrical energy
229
What is the difference between a primary cell in a battery and a secondary cell?
Primary cell - active material cannot be restored.
Secondary cell - electricity can restore active material to a charged condition.
230
Batteries consisting of secondary cells are called ______
storage batteries
231
The open-circuit voltage of a lead-acid battery is _____
2.1 volts per cell
232
The battery ______ gives a good indication of the battery's charge.
specific gravity
233
Definition of specific gravity
ratio of the weight of a given volume of a material to the same volume of pure water.
234
What is the average specific gravity of a fully charged battery?
1.275 - 1.300 at 80°F
235
Definition of capacity of a battery
ability to produce given amount of current for a specified time.
236
capacity is measured in _______
ampere-hour
237
2 methods of charging battery
1. Constant-current
2. Constant-voltage
238
constant-current charging should be done at a rate of no more than _____ of the battery's ampere-hour rating.
7°
239
In the constant-voltage method of charging the amount of current that flows into a battery is determined by the battery's ________.
state of charge
240
Why do turbine engines need Nicad batteries?
require an extremely high current for starting.
241
Definition of ampere-hour
amount of electricity put into or taken from a battery when a current of 1 ampere flows for 1 hour.
