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INSTALLER TECHNICIANINSTALLER TECHNICIAN
Exploring ElectronsExploring Electrons
and and
ElectricityElectricity
Module #2 - 270-21-1Module #2 - 270-21-1
LESSON OBJECTIVESLESSON OBJECTIVES
Summarize major characteristics of electron Summarize major characteristics of electron orbits and orbital shells. (pg’s 2-3)orbits and orbital shells. (pg’s 2-3)
Define electron characteristics of the shell Define electron characteristics of the shell capacity, valence shell, and electron energy capacity, valence shell, and electron energy level. (pg’s 3-6)level. (pg’s 3-6)
Define and identify the types of conductors and Define and identify the types of conductors and insulators. (pg’s 7-8)insulators. (pg’s 7-8)
Define semiconductor characteristics. (pg 9)Define semiconductor characteristics. (pg 9) Describe electron current flow. (pg’s 10-11)Describe electron current flow. (pg’s 10-11)
LESSON OBJECTIVESLESSON OBJECTIVES
Describe energy transfer that produces electrical Describe energy transfer that produces electrical current. (pg 12)current. (pg 12)
Define the electrical current characteristics Define the electrical current characteristics regarding speed and the amount of current. regarding speed and the amount of current. (pg’s 12-13)(pg’s 12-13)
Define electromotive force, potential difference, Define electromotive force, potential difference, and voltage (pg’s 16-17)and voltage (pg’s 16-17)
List the units of measurement for voltage (pg 20) List the units of measurement for voltage (pg 20)
List the units of measurement for current (pg 20) List the units of measurement for current (pg 20)
Conductors, Semiconductors & Insulators
Most materials belong to one of Most materials belong to one of three broad groups: three broad groups: conductors, insulators, and conductors, insulators, and semiconductors. The semiconductors. The borderlines are not clear, borderlines are not clear, though, and many substances though, and many substances cannot easily be put into one cannot easily be put into one group or the other.group or the other.
Atomic structure of conductors, insulators, and semiconductors
Insulator - full valence shell
Conductor - 1 to 2valence electrons
Semiconductor - 4valence electrons
Atomic structure of conductors, insulators, and semiconductors
Conductor - 1 to 2valence electrons
IMPORTANTIMPORTANTThe 3rd orbital shell has a maximum capacity of 18
electrons
Atomic structure of conductors, insulators, and semiconductors
Semiconductor - 4valence electrons
IMPORTANT NOTE:The # of valence electrons in the valence shell determines what a particular element it is .
Electricity-the flow of free electrons
Bound electron Free electron
Valance electron
Negative source
Positive source
NN
NN
The center of an atom is called the nucleus.Most atoms have neutrons which have no charge.A nucleus also has protonsand they have a positive charge.
Negative electronsorbit the nucleus.
NN
NN Negative electronsorbit the nucleus.
IMPORTANT NOTE:IMPORTANT NOTE:The attraction between the positive nucleus and the negative electrons keep the electrons from breaking away from the nucleus even at high speeds.
NN
NN
This is a copper atom.
It has 29 protons.
It has 29 electrons.
Its net charge = 0.
Valence electron
The valence electron
The nucleus plus the inner electron orbits
A simple model of the copper atom looks like this:
Copper wire is usedto conduct electricitybecause the valence
electrons move freelythrough its structure.
Remember, the valenceelectrons are weakly
attracted to the nuclei.
So far, we know that copper’s single valence electron makes it a good conductor.
It acts as an electrical insulator.
The rule of eight states that a material like thiswould be stable since its valence orbit is full.
No Vacancy
VOLTAGE & CURRENTVOLTAGE & CURRENT
VOLTAGE = VOLTSVOLTAGE = VOLTSAC = AC = DC =DC =
CURRENT = AMPERES (A)CURRENT = AMPERES (A)
VOLTAGE - The difference in electric potential between two charges.
1 Volt
- Difference in Electric Charge
1 Ohmof Resistance
Produces 1 Ampereof Current Flow.
* IMPORTANT ** IMPORTANT *
CURRENT - The rate of flow of electrons- The rate of flow of electrons
MeasurementPoint
= One Coulomb= One CoulombPer SecondPer Second
= One Ampere= One Ampere
-12-12 -9-9 -6-6 -3-3 00 +3+3 +6+6 +9+9 +12+12
picopico nanonano micromicro millimilli 00 KiloKilo MegaMega GigaGiga TerraTerra
Metric Prefixes
USING UNITS OF ELECTRICAL MEASUREMENTS
______1______ 1____ 1000 1,000,000,0001,000,000,000,000 1,000,000 1,000,000
_______1______ ___1___ 1,000,000,000,000
1,000,000,000 1000
10-9
10-12 10-610-3
103 106
109 1012
(p) (n) (u) (m) (K) (M) (G) (T)
m(MILLI)
PREFIX CHART
BASE UNITS
33
3 3
Movement of Decimal Point to and from Base Units
3
3
M(MEGA)
k(KILO)
3
3
(MICRO)
EXAMPLES OF CONVERTING UNITS
0.012 A =___ mA12 (move 3 decimal places to the right)
450 mA = ___ A (move 3 decimal places to the left)0.45
47 000 = ___ k (move 3 decimal places to the left)47
2.2 M = _________ (move 6 decimal places to the right)2 200 000
500 A = _________A (move 6 decimal places to the left)0.000 5