CENT-112-2

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CENT-112 Fundamentals of Electricity and Electronics1

Section 1: Fundamentals of

Electricity & Electronics

Safety Precautions Basic Electrical Terms and Circuits

Basic Measuring Instruments

Basic Electrical Circuit Materials

Energy

Sources of Electricity

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A GOOD THING TO KEEP IN

MIND!

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THE BEST TOOLS EVER

INVENTED HANDS!

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SAFETY SHIELDS ARE EYE

INSURANCE!

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SAFETY SHOES ARE NOT FOR

DEFEAT!

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HEARING PROTECTION IS

FOR WINNERS!

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Always check Electrical Circuits

Deenergized

Discharge capacitors.

Check Power Leads (T1-T3)

Check Capacitors discharged. < 30VAC is deenergized.

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Electrostatic Discharge (ESD)

Invisible Threat

1 touch can ruin this card.

Wear a wrist strap.

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General Safety Rules

1. Do not work when you are tired or takingmedicine that makes you drowsy.

2. Do not work in poor light.

3. Do not work in damp areas or with wet or dampclothing and shoes.

4. Use approved tools, equipment, & protective

devices.5. Remove all metal items when working around

exposed circuits.

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General Safety Rules Continued

6. Never assume that a circuit is off. Double-check it with an instrument that you are sure is

operational.

7. Buddy system is used at circuit breakersupplying power if working on circuit.

8. Never override safety interlocks.

9. Keep all tools and test equipment in goodworking condition.

10. Discharge capacitors.

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General Safety Rules Continued

11. Do not remove grounds and do not use adaptersthat defeat the equipment ground.

12. Use CO2 or halogenated-type fire extinguisherto put out electrical fires. Water conducts

electricity! (i.e. galley fire in oven).13. Store solvents and other chemicals in

appropriate areas. (i.e. fire personnel incident).

14. Do not work on unfamiliar circuits.15. Do not cut corners or rush. No horseplay or

practical jokes in the labs (i.e. throwing caps,meggering).

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Shock Victim

Do not become part of the problem. Use non-conductive belt and break free shock

victim.

Call for medical assistance. (911)

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Review CPR

Check for response. Have someone call 911.

Clear airway.

Look, listen and feel for breathing.

Give 2 full breaths.

15 compressions (1 and 2 and 3)

Continue till medical help arrives, you are

relieved or are too tired to continue.

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Questions

Q1. Who is responsible for safety?

A1. Everybody is responsible for their safety.

Q2. What protects electronic circuits from ESD? A2. ESD packaging & wrist straps.

Q3. What is the worst electrical shock you have

heard of or experienced? A3. Various.

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Scientific NotationPrefix Symbol Decimal Power of Ten

tera T 1,000,000,000,000 1012

giga G 1,000,000,000 109

mega M 1,000,000 106

kilo k 1,000 103

basic unit 1

milli m .001 103

micro .000001 106

nano n .000000001 109

pico p .000000000001 1012

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Ohms Law

E

I R

E=IR

Given:

E = Voltage

I = Current

R = Resistance

I = E/R

R = E/I

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Questions

Q4. Given a 1 Megohm resistor with a 120 voltpotential applied to it, what current will pass

through it?

A4. .12 milliamps Q5. Can this current kill you if you touch it?

A5. No. .1 Amp for 1 second can be fatal.

Q6. How many students know CPR? A6. It is a good thing to be qualified in CPR

when working on or near electrical circuits.

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Questions Continued

Q7. Given a 1.5 Amp battery charger with a totalcircuit resistance of 8 ohms, what supply voltage

is generated?

A7. 12 volts

Q8. What amperage is present when you place

the new chip in your cellular phone?

A8. micro amps.

Q9. What amperage is present when you put

leads on a new car battery?

A9. milliamps

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Atomic Theory

Foundation for Solid State Devices

Atom - Smallest part of an element thatretains the characteristics of that element.

Molecule Smallest part of a compound.

Compound- 2 or more elements

chemically combined.

Definitions

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Atom Parts:Electrons: Negative part of an atom.

Protons: Positive part of an atom.

Neutrons: Negative part of an atom.

The Atom

N

PN

P

E

E

E

E E

E

E

E

E

E

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Static Electricity

Like charges repel each other and unlike chargesattract each other.

Walking across a wool or nylon rug , you can

generate a static charge of electricity, dischargingseveral thousand volts of electricity to a metallic

object like a door handle.

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Definitions

Coulomb: Practical unit of measurement of theamount of electricity. Used to describe the flowof electricity.

1 Coulomb = 6.24 X 1018 electrons.

Electrostatic or Dielectric field: The field orforce surrounding a charged body.

Charge Transfer

Direct Contact Induction: Electron flow due to charged object in

close proximity.

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Valence Electrons are those electrons whichare located in the outermost or Valence

shell of an atom.

The number of valence electrons an atoms

has determines the electrical properties ofthat atom.

< 4 electrons => Conductor

> 4 electrons => Insulator

4 electrons => Semiconductor

Energy Band Diagrams

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Energy Band Diagrams Continued

Conductor Semiconductor Insulator

Valence Band Forbidden Band Conduction Band

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Covalentvs. Ionic Bonding

OctetRule and Covalent Bonding

N and P Crystals

Base Material - Silicon or GermaniumDoping - Process by which impurity atoms are

added into a pure base material to create a

compound with improved electrical properties. This

process is used when making semiconductors.

Bonding

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Static Device Application

Electrostatic Precipitator: Collector Plates needcleaning.

Oil

Mist

Mechanical

Filter

Ionizer Plate:

Positively charges

Particles in air

Collector Plate:

Negative plates

collects + ions.

Clean

Air

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Basic Electrical Circuit

Power Supply

(Source)

Conductor

Load

(Light)

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Types of Current

AC: Alternating Current

DC: Direct Current

0

+

-

0

+

-

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Circuit Flow

Conventional Current Flow: Hole flow.

Electron Flow Series Circuit

Parallel Circuit

Series/parallel Circuit

Documents

CENT-112-2