M3 Flashcards
1
Q
Are protons negatively charged
A
No, they are positively charged
2
Q
What is a neutron
A
Neutral particles with a charge of 0. They ensure that positively charged protons don’t repel.
3
Q
What is an electron
A
A negatively charged particle that travels on the shells or orbits.
4
Q
Why don’t electrons move away from the nucleus
A
Because of the centrifugal force which attracts the electrons towards the positively charged protons.
5
Q
When is an atom electrically neautral
A
When number of protons and electrons is the same
6
Q
What is an ion
A
A positive or negatively charged atom. Happens through ionisation
7
Q
What is a molecule
A
An electrically neutral group of two or more atoms held together by chemical bonds. Distinguished by their lack of electrical charge.
8
Q
What is a cation
A
A positively charged ion
9
Q
What is an anion
A
A negatively charged ion
10
Q
What do cations and anions do together
A
They attract to each other and form ionic compounds like salts
11
Q
what is a compound
A
A chemically bonded substance so posed of two or more identical molecules. Composed of atoms from more than one element.
12
Q
What are the four types of bonds
A
Convalent bonds
Ionic bonds
Inter metallic compounds
Certain complexes held together by coordinate covalent bonds
13
Q
What is a conductor
A
It has less than 4 electrons. 3 or less in valance shell.
14
Q
What are the characteristics of a conductor
A
Metals
Closely packed and have a crystal lattice
High density, which allows electrons on outer shell to separate from their atoms and move within the atomic structure.
Hugh mobility of electrons
15
Q
What is a semiconductor
A
An atom that has 4 electrons
Conductivity is produced by adding other forge in atoms - dopping
16
Q
What are some example of semi conductors
A
Silicon
Germanium
17
Q
What is an insulator
A
Also known as non conductors
Has more than 4 electrons on valence shell.
Has no free electrons therefore cannot be conducted
The structure of electrons is tightly packed therefore means electrons cannot break away
18
Q
What is an example of insulators
A
Micra
Porcelain
19
Q
What is static electricity
A
When two materials are rubbed against each other and some electrons from one material are handed over to the other material. The electrons that are given are called free electrons and are in the valence shell
20
Q
How can static electricity be produced
A
Contact
Friction
Induction
21
Q
What is an example of static friction
A
When a glass rod is rubbed with fur it becomes negatively charged. Whereas if it is rubbed with silk it becomes positively charged
22
Q
What is the law of attraction
A
Opposites attract
23
Q
What happens to the lines of force
A
They extend in all directions from the charged body and terminate where there is an opposite charge
24
Q
Why are metals good conductors
A
As they have a vast number of free electrons available
25
What happens when you apply a force to a solid
Electrons flow from a negative to the positive pole
26
What happens when an electron enters a conductor
Another electron at opposite end of conductor is pushed out.
27
What is the movement of an electron called
Current
28
What happens if the current remains constant
The same number of electrons flow through a conductor regardless of its cross section area
29
What does it mean if a conductors cross section is smaller
It means the electrons are more closely packed together. Therefore heating is higher. Therefore electron ion collisions occur more often with higher intensity. Increasing heating.
30
What is the formula for current density
Current density = Current [A] / cross section area [mm2]
J = I / A
31
What does a greater density in a conductor mean
More heat is produced.
32
What is the maximum a cable can be heated to
60 degree c. For each given cross section an ambient temp of 25 degrees c
33
Is water a conductor
Pure water is not a conductor. As it does not contain any ions so electrons do not move through the solution
34
Is Tap water a conductor $$$$$$
Yes. As it contains hydrogen and oxygen. Of DC is applied hydrogen is generated at negative pole and oxygen at positive.
35
What is it meant by the decomposition of chemical compounds
The passing of an electric current through a liquid which is called electrolysis. The conducting substance is called an electrolyte
36
What is an electrolyte
The conducting substance that occurs when an electric current passes through
37
Where can you find the condition of electricity in gases
The application of gases can be found in the filament builds with a higher electrical output of 60w
38
Why would you find a gas in a filament light bulb
To prevent it from burning oxidising or vaporising. Gases such as nitrogen argon and krypton
39
What is the production of electrical continuity in gasses or metal vapours
The production of light
40
What is the process of light by gasses called
It is called gas discharge, happens to fluorescent tubes
41
Why does gas discharge happen
Due to the heat. The molecules or atoms move to and from random layers without combining with each other. The gas atoms that are enclosed in the bulbs are electrically neutrals so no need to combine.
Electrons of fewer atoms will split if for energy supply then freely moving charge carriers are generated. The current increases in such a way that it has to be limited with resistance.
42
What does gas discharge arise from
Electrons and positive ions therefore being it neutral.
43
What is an oscilloscope
Provides a visual isotion of rapidly varying processes in electrical engineering
44
What is an oscillograph
Rapidly varying electrical process which can be permanently recorded. Whereas using a oscilloscope the processes can be visualised but not recorded. More so pictures.
45
Do more on oscilloscope etc
46
What is potential difference
Always arises between two differently charged points. When there is an deficiency of electrons at one point and an excess at another point.
47
How do you generate voltage
By separating negative and positive charges
48
What is a generator
It draws electrons from positive pole and transports them to negative pole so potential difference is maintained and therefore produces an electrical voltage. Not the only way to produce it tho.
49
Add more on how to produce voltage.
50
What is EMF
electromotive force.
51
What does the electromotive force do.
A force that acts in a way that a body is pushed pulled or lifted. As electrical charges will exert a push or pull force on each other without actually coming into contact with each other.
52
Who developed the electric field theory
Faraday
53
How can electrical attraction and repulsion was shown
By electrical flux line. Yet they are invisible in real life. The more lines the stronger the field would be. The lines also take the shortest means possible to get from a positive to a negative charge.
54
What does the density of flux lines red present
The quantity of electrical excitement between charges
55
What is voltage
Also known as electric pressure. It’s the difference in electrical potential between two points. The force that acts on electron to cause it to move.
56
What does distance between for an electron and nucleus
The greater distance between the electron and nucleus the stronger the potential energy of electron.
57
What is DC
Direct current. The charge carriers consistently flow in same direction at same current
58
What is AC
Alternative current. A flow of charges repeatedly changing direction and current in a certain time period
59
What is the value of 1 ampere
6.24 x10 18 electron/sec
60
How can you measure current
Ammeter or current meter
61
What is the charge of a single electron
-0.1602 x 10 -18 C
62
How many electrons are in the valance shell for a good conductor
3 or less
63
If you were to rub a glass rod with silk it would become what charge
Positive
64
Opposite charges do what and like charges do what
Opposite charge and like charges repel
65
What is a battery made up off
Two different materials and an electrolyte
66
If you increase distance between electron and neutron what happens
Potential energy/ voltage increases
67
What will a nickel cadmium cells voltage be when it is discharged
1 volt
68
What would chromel alumels mv change by its temperature increases by 100 degrees c
353.5volts
69
What is superimposed voltage
Goes below zero but inconsistent to rest of graph
70
What is a generator
A device which separates charge
71
What is emf
Electromotive force
72
How does current density affect heat
The greater the current density the more heat that’s produced
73
What is the liquid in electrolysis
Electrolyte
74
What is gas discharge
The electrical continuity in gases or metal vapour which results in light
75
What is the speed of movement of charges depends on
Temp
Cross section
Conductor materials
76
What is 1 amp
6.24 x 10(18)
77
What’s the device called for recording oscillations?
Oscilloscope
78
What are the two kinds of voltage and what do they do
AC - changes polarity
DC - same polarity (direction)
79
Is pure water a conductor?
No but tap water is as it has other chemicals in it
80
What is the maximum temperature for cables
60 degrees
81
What is testing temp for cables
25 degrees Celsius
82
How to work out current density
Current/ cross sectional area
83
What charge does a glass rod have when rubbed with fur and silk
Fur - negative
Silk - positive
84
Examples of insulators
Porcelain
85
What is doping
Adding foreign atoms
86
Insulators have how many electrons in valance orbit
5 or more
87
Semi conductors have how many electrons in valance orbit
Exactly 4
88
Good conductors have fun how many electrons in valence orbit?
3 or less
89
Four types of bonds
Covalent, ionic, intermetallic, coordinate covalent
90
What happens to conductance when resistance is high
Low conductance
91
Charge of an electron
-0.1602 x 10 (-18)
92
What if the electrostatic law of attraction?
Opposite charges attract
Same charges repel
93
What are the 4 types of bonds
Covalent
Ionic
Intermetallic
Coordinate covalent
94
What type of cells generate light
Photocells
95
Good conductors have how many electrons in valance orbit
3 or less
96
3 main components to a three phase principle
120 degrees between coils and wavelengths
115v between 1 phase and neutral
200v between 1 phase and another phase
97
What is electron emission
The superstation of electrons from a metal bonding. It’s a common method of doing this by heating
98
What is the charged rate of lead acid
2v
99
What is the charged rate of nickelncadminium
1.2v
100
How does pressure produce heat
Crushing piezo crystal
101
How do you increase voltage
Increase magnetic speed strength
Increase movement speed
Length of conductor
102
Difference between primary and secondary cells
Primary cells aren’t rechargeable whereas secondary are
103
What’s the charged and discharged voltage of lead acid
Charged - 2v
Uncharged - 1.83v
104
What’s the charged and discharged voltage of nichel codmium
Charged - 1.2v
Discharged 1v
105
What’s the most common secondary cell
Lead acid and nickel codium
106
What’s the mix of the electrolyte consist of and percentage
70/30
Suphric acid and water
107
Advatanges of using a nickel codium battery over a lead battery
Larger capacity
Better power to weight ratio
108
Voltage
The difference in energy between electrical charges or potentials.
The force that acts on electrons cause to move
109
What happens when the distance between the electron and nucleus gets bigger
The stronger the potential energy of electron gets.
110
What is direct current
If voltage has the same polarity over time. Either positive or negative. Doesn’t change - singular direction
111
What is a voltmeter
Is connected in parallel with the terminals of a power source.
112
Two ways to measure voltage
Analogue meter - pointer deflection
Numerical read out - digital meter
113
What does 1v equal
1000mv
114
What is electrical current
The flow of electrical charges in a certain direction
115
What’s the equation for current
Current = charge / time or current = volt/ resistance
116
Is an electrical current a flow of electrons
No not necessarily. There are other charge carriers that cause the flow of electrons
-in solid conductive materials - electron currents
117
What’s is dc
Direct current - the charge carriers constantly flow in same direction at same current
118
What is ac
A flow of charges repeadily changing direction and current in a certain period of time
119
1 ampere =
1 ampere = 6.24 x 10 (18) electron/second
120
How do you measure a current of a series
The charge carriers flow through a Ammeter or current meter
121
What’s is resistance
A measure of the opposition to the current flow of an electrical circuit
122
What is resistance
Measure of its opposition to the flow of electrical current. The breaking action of a conductive material, therefore dependent on atomic density of material. - closer the ions are the greater the braking action
123
What is ohms law
The relationship between current, voltage and resistance
124
What is the ohms law equation
Volatage = current x resistance
125
What is conductance
The ease with which electric current flows through materials
126
Conductance
Higher resistance = lower conductivity
Lower resistance = higher conductivity
127
What’s is the equation for resistance
G = 1/R measured in siemens (s)
128
What is charge
The sum of all electrical charges is the quantity of electricity - called charge
129
What’s is the si unit for charge
Coulomb (C) 1c = 6.24 x 10(18) electrons
130
What’s is the equation for charge
Charge = current/time
131
What is conventional current flow
The electric current flows from positive to negative pole
132
Electron flow
direction of electrons is flowing through a conductor depends on applied voltage. If the polarity of the voltage is not changing then electrons will flow through the same direction - DC
If changing polarity then it’s - AC
133
How does light generate electricity
By a photocell
134
Semi conductor materials
Silicon and germanium
135
What is a photocells function
Generates electric voltage as they are energy converters
136
What effects the amount of electricity generated by a photocell
Time, intensity,colour, type
137
What’s the device called for recording oscillations?
Oscilloscope
138
What’s gas discharge
Electrical continuity is gases or metal vapour which results in light
139
What’s the liquid called in electrolysis
Electrolyte
140
How do you get current density
Current/cross sectional area
141
What are the two types of voltage and what’s the difference
Ac- changes polarity
Dc- same polarity
142
Whats the charge of 1 amp
6.24 x 10 to power of 18
143
Speed of movement of charges depends on
Temp, cross sectional area, conductor material
144
How does current density affect heat
The greater the current density, the higher the heat
145
Whats EMF
Electromotive force
146
What’s a generator
A device that splits/separates charges
147
What’s si unit of charge
Columbs
148
How’s static electricity produced
Contact, friction, induction
149
What are thermocouples used for in aviation
Measuring exhaust gas temps
150
What’s the Most common thermocouple
Chromel and alumel
151
What’s the positive and negative plates of nickel cadmium made up from
Positive plate is made up from nickel oxy hydroxide
Negative plate is made up from metallic cadmium
152
What does the positive and negative plates of lead acid consist of
Positive is made up from lead peroxide
Negative is made up from spongy lead
153
In a series cell what happens to volts and amps
Volts increase and Amps stay the same
154
What determines amount of voltage generated through induction
Magnetic field strength, length of wire, speed of motion
155
What’s the action called that occurs in a battery cell
Galvanic cell
156
Advantages of using nickel cadmium batteries over a lead battery?
Larger capacity, better power to weight ratio
157
What’s the mix of the electrolyte in lead acid
70 percentage sulphric acid
30 percentage water
158
Most common secondary cell
Lead acid and nickel cadmium
159
What’s the charged and discharged voltage of nickel cadmium
Charged 1.2
Discharged 1
160
What’s the charged and discharged voltage of lead acid
Charged 2
Discharged 1.83
161
Difference between primary and secondary cells
Primary’s are one use and can’t can’t be recharged whereas secondaries can
162
How do you increase voltage
Increase magnetite strength, increase movement strength, length of conductor
163
How does pressure produce heat
Crushing the piezo crystal
164
What’s the electrostatic law of attraction
Opposite charges attract whereas same charges repell
165
Charges of an electron?
-0.1602 x 10 to the power of minus 18
166
What types of cells generate light
Photocells
167
If dc’s applied to water what’s generated at either pole
Negative- hydrogen
Positive- oxygen
168
4 types of bonds
Inter-metallic, covalent, ionic, coordinate convalent
169
What’s doping
Adding foreign atoms
170
Examples of insulators
Porcelain
