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

Insulator - full valence shell

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 .

Structure of an atom

Neutron

Proton

Electron

Shell or energy level -

+

-

+

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

NN

NN

Valence electron

Its attraction to the nucleus is relatively weak.

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