Download KENTUCKY TECH ELIZABETHTOWN

ELIZABETHTOWN COMMUNITY AND TECHNICAL COLLEGE
BEX 100 BASIC ELECTRICITY FOR NON MAJORS
LECTURE GUIDE – UNIT 1
Instructor: Jerry Brown
Reference: Delmar’s Standard Textbook of Electricity, Third Edition
ATOMIC STRUCTURE
Objectives
At the completion of the lesson, the student should be able to:
1. List the three major parts of an atom
2. State the Law of Charges
3. Discuss the Law of Centrifugal Force
4. Discuss the differences between Conductors and Insulators
Terms to Know
Atom
Alternating Current (AC)
Centrifugal Force
Conductors
Direct Current (DC)
Electron
Electron Orbits
Insulators
Matter
Negative
Neutron
Nucleus
Positive
Proton
Semi-Conductors
Valence Electrons
HISTORY OF ELECTRICITY
Greeks discovered about 2000 years ago
Has been used practically only about 100 years
Amber became charged when rubbed with other materials
Attracted things like leaves, feathers, bits of cloth
Word “Electric” comes from Greek word “Elektron”
Positive Charges (List A)
Negative Charges (List B)
STUDY OF ATOMS
Atom is the basic building block of the Universe
All matter is made of a combination of atoms
Matter – Any substance that has mass and takes up space
Matter can exist in three forms: Solid, Liquid, Gas
Element: Can’t be divided into a simpler substance
Three States of Water: Solid (Ice), Liquid, Gas (Vapor/Steam)
Parts of an Atom:
Electron
Proton
Neutron
Examples:
Helium Atom
Copper Atom
Proton – Positive charge
Electron – Negative Charge
Neutron – No charge (Neutral)
LAW OF CHARGES
Opposite charges attract; Like charges repel
Valence Electrons
Outer shell of the Atom is known as the “VALENCE SHELL”
Electrons located in the outer shell are “VALENCE ELECTRONS”
The Valence Shell can’t hold more than 8 Electrons
Current Flow – Electrons move from atom to atom
INSULATORS – have 7 or 8 electrons in their Valence Shell
SEMI-CONDUCTORS – Have 4 electrons in their Valence Shell
CONDUCTORS – 1 or 2 electrons in their Valence Shell
They give up their electrons with little effort
They allow current flow easily (Low Resistance)
Examples of Good Conductors:
Silver – 1 Valence Electron
Copper – 1 Valence Electron
Gold – 1 Valence Electron
Aluminum – 2 Valence Electrons
Platinum – 1 Valence Electron
INSULATORS
Materials that have 4 Valence Electrons
Resist flow of electricity
Electrons are held tightly and are not given up easily
Examples:
Rubber
Plastic
Glass
Wood
2
SEMI-CONDUCTORS
Materials that have 4 Valence Electrons
Are neither good insulators nor good conductors
Used to make Diodes and Transistors
Computers are full of semi-conductors
Silicon and Germanium are the most common materials used
METHODS OF PRODUCING ELECTRICITY
Magnetism – Generators
Chemical – Battery
Pressure – Piezo Sensors
Heat – Thermocouples
Friction – Static
Light – Photovoltaic
REVIEW QUESTIONS
1. What is the Valence Shell?
2. List the three main parts of an atom and their charges:
3. What is the maximum number of electrons that the outer shell can hold?
4. How many electrons are in a Conductor’s outer shell?
5. How many electrons are in an Insulator’s outer shell?
6. What is electricity?
7. How many electrons are in a Semi-Conductor’s outer shell?
8. State the Law of Charges.
9. What keeps electrons from falling into the Nucleus?
10. What does the prefix “kilo” mean?
3