Fundamentals of Electricity - A Reasearch Project from Marikina Polytechnic College

FUNDAMENTALS OF ELECTRICITY

ELECTRICITY DEPARTMENT

MARIKINA POLYTECHNIC COLLEGEMARIKINA CITY

MARIKINA POLYTECHNIC COLLEGE

COLLEGE OF TECHNICAL TEACHER EDUCATION

FUNDAMENTALS OF ELECTRICITY

A module presented to the faculty of Electrical Department

In partial fulfillment of the requirements in

Technical Writing in the Discipline

PREPARERS:

Donna Femie C. Calimbayan

Genelan C. Francisco

Jerwin V. Lopez

Gio P. San Buenaventura

BTTE ELECTRICAL TECHNOLOGY

March 2014

I

TABLE OF CONTENTS

ACKNOWLEDGEMENT………………………………………………………..…. II

PREFACE………………………………………………………………………….... III-IV

PRE-TEST…………………………………………………………………………... V-X

UNIT I INTRODUCTION TO ELECTRICITY……………………….…….. 1-14

UNIT II COMPARISON OF AC TO DC ……………………………….…… 15-20

UNIT III OHM’S LAW…………………………………………………………. 21-27

UNIT IV ELECTRICAL CIRCUITS ………………………………………….. 28-34

UNIT V ELECTRICAL POWER AND ENERGY ………………………….. 35-37

UNIT VI CONDUCTORS AND INSULATORS ……………………………. 38-45

UNIT VII WIRES AND CABLES …………………………………………...… 46-58

POST-TEST……………………………………………………………...………….. 59-65

ANSWER KEY …………………………………………….……………………….. 66-70

TECHNICAL TERMS USED IN THIS MODULE ……………………………….. 71-72

REFERENCES……………………………..……………………………………….. 73-75

ABOUT THE AUTHORS…………………………………………………………… 76

ABOUT THE REVIEWERS…........................................................................... 77

II

ACKNOWLEDGEMENT

We would like to extend our gratitude to all those people who helped and

supported us in completing this module. Especially we would like to thank our beloved

evaluator Mr. Ramil A. Caballero for the lessons, advices on what to do, and guidance.

In addition, our former instructor in high school Mr. Jomar P. Mogado of Malanday

National High School for giving us such ideas in improving our module.

Moreover, we would also want to express our gratefulness to the one who gave

this task on module writing Ms. Cecile I. Vizcaya, we are very thankful because these

tasks give us lessons. In addition, we would like to thank her for motivating us to work

hard and finished this module.

In addition, we express our sincere gratitude to our families who understood and

encouraged us in every time we spent in making this module.

Last but not the least; we would like to extend our heart-felt gratitude to our Lord

in guiding us in making this module.

Finally, thank you to all who helped us may good God bless you all.

III

PREFACE

Electricity plays an important role on human necessities. From giving our lives

simple and easy through human innovations. It is also the most useful discovery of man

that leads from simple tool to the most advance gadgets today.

This module deals with the basic fundamentals of electricity to guide students in

learning such field of specialization. The module covers such information that helps

students and instructors for their field of study, specially the beginners. It contains the

topic that will surely have a great contribution in terms of electrical technology; it

includes the history of electricity, theory, purposes and the basics in the field of

specialization.

This module has seven (7) units. Each unit has the following parts: Learning

Outcomes, Information Sheet, Exercises, Performance Sheet, Activity Sheet, Pretest,

and Posttest. To get the most from this module, you need to do the following:

1. Begin it by taking the pretest, you will find out what you already know and check

your answer by proceeding in the Answer Key. If you already know the topic and

you got a high score, you may proceed to the next lesson. That means you don’t

need to go through the unit because you already know what it is all about. If you

failed to get a perfect or almost perfect on the score, go through the lessons

again and review especially to the items which you get fail.

2. By reading the introduction and learning outcomes, will tell you what should you

know and be able to do at the end of this module.

3. By Begin in the Information Sheet. An Information Sheet contains important

notes or basic information that you need to know.

After reading, go through the exercises. Test yourself on how much you have

learned in the unit that you read. If any, demonstrate what you have been learned by

doing what the Activity Sheet and the Performance Sheet directs you to do.

IV

After all the chapters, answer the post test. This will determine how much do you

understand on the module.

You must be able to apply what you have been learned in another activity or in

real-life situation. Each lesson also provides you with references and definition of the

key terms for your guide. Use them fully, they can be a great help to you.

We expect that this module gives satisfaction to those who will read and benefit

this module, and to give help to those who teaches this study as a supplementary tool

for their teaching.

The Writers

REMEMBER!

If you have any questions, do not hesitate to ask your instructor for assistance.

V

PRE-TEST

I. Directions: Read the following questions then encircle the letter of the best

answer.

1. The same electrical charge ___________ each other.

A. repels B. attracts C. neutralize D. destroy

2. It is classified neither negatively nor positively charged particles.

A. electrostatic force

B. electron in motion

C. atom

D. neutron

3. The equal number of electron and proton in an atom.

A. negative B. positive C. neutral D. none of the above

4. It stated on Electron Theory that all matter is made up of _______________.

A. neutron B. atom C. molecules D. electron

5. The smallest particle of molecule.

A. proton B. ion C. atom D. electron

II. Read the following question then choose the letter of the correct answer in the

box below. Write your answers on the space provided.

_________ 6. What do you find at the center of an atom?

_________ 7. What is the attraction between the electron and the nucleus?

_________ 8. What do you call the negatively charged particle of an atom?

VI

_________ 9. What do you call the positively charged particle of an atom?

_________ 10. What particle of an atom is not electrically charged?

III. Directions: Identify the following. Write the answer on the space below

11. Causes electrons to flow in a single direction along the wire.

_______________________________________________________

_

12. It is replaced Edison's DC battery system.

_______________________________________________________

_

13. Instead of applying the magnetism along the wire steadily, he

used a magnet that was rotating.

____________________________________________________

14. It is the flow or rate of flow of electric force in the conductor.

_______________________________________________________

_

15. Two classification of Electric Current

VII

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IV. Directions: Tell whether the following idea refers to Alternating Current or Direct

Current. Write AC if the answer is Alternating Current and DC if it is Direct Current.

Write the answer on your paper.

16. Electrons keep switching directions - forward and backward.

________________________________________________________

17. The frequency is 50Hz or 60Hz depending upon the country.

________________________________________________________

18. Obtained from Cell or Battery.

________________________________________________________

19. Safe to transfer over longer city distances and can provide more power.

________________________________________________________

20. Electrons move steadily in one direction or 'forward'.

________________________________________________________

V. Direction: Find the missing quantity for each of the circuits below.

21. 5Ω I=2AV=?

VIII

________________________________________________________

22.

________________________________________________________

23.

________________________________________________________

24.

________________________________________________________

25.

________________________________________________________

I=2A

R=?

20V

I=?

10V

R=5Ω

R=?

1000V

I=500A

R=10Ω I=0.4AV=?

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VI. Directions: Match Column A with Column B. Write the letter of the correct

answer on the space provided.

A B

____ 26. Switch A. current cannot pass through the bulb

when the other filament of the bulb is cut

____ 27. Source of power B. caused the load to light up

____ 28. Conductor C. consumes power

____ 29. Load D. electrical path

____ 30. Series circuit

connection

E. bulb has its own circuit

F. control the circuit

VII. Directions: Identify the following. Write the answer on the space provided

________________31. It is the rate at which energy is used or the rate at

which work is done.

________________32. The measuring unit of electrical power is watt, named

after Scottish inventor and mechanical engineer.

________________33. It is one of the basic quantitative properties describing

a physical system or object's state.

VIII. Directions: Multiple Choices. Encircle the correct answer below.

34. Which of the following would normally be the best conductor?

X

A. copper

B. glass

C. steel

D. silver

35. Which of the following determines how good a material is as an electrical

conductor?

A. its superior strength in hot and cold weathers

B. the type of atoms that make up the material

C. the purity of the sample

D. when the electrons are free to flow

36. Substances that do not allow electricity to pass through them are:

A. conductors

B. cells

C. insulators

D. wires

37. What are those electrical conductors 8mm2 (AWG no. 8) and smaller sizes.

A. cables

B. wires

C. cord

D. cable wires

38. It is consist of group of wires twisted to form a metallic string.

A. stranded wires

B. solid wires

C. cable wires

D. cord

39. If a wire has a diameter of one mil, what is the cross sectional value of the

conductor.

A. One circular mil

B. One hundred circular mil

C. One thousand circular mil

B. One million circular mil

40. What do you call the larger conductors than the wires?

XI

A. Wires

B. Cables

C. Cord

D. Conductors

PRINCIPLES OF ELECTRICITY INTRODUCTION

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UNIT I

INTRODUCTION TO ELECTRICITY

Electricity plays an important role in man’s conquest for existence. It figures

everywhere in our lives. It lights up our homes, cooks our food, powers our computers,

television sets, and other electronic devices. Electricity from batteries keeps our cars

running and makes our flashlights shine in the dark.

It has been said that it is here with us since the beginning of the time. Before we

live, it already exists in many things, like in friction, lightning, etc. It has also many

sources like tides, solar, wind, etc. It is stated that electricity was the very useful

discovery that a person did.

Where does our electricity come? Most of the electricity we use each day comes

from a power station. Large fan-like machines called turbines turn to create electricity.

The electricity reaches us by travelling along wires strung from power poles or towers,

or run underground. This allows us to switch on our lights, heat and cool our homes and

use our appliances.

In the end of the unit, you must be able to:

1. Understand the history of electricity.

2. Identify major sources of electricity.

3. Analyze the theory and principles of electron.


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INFORMATION SHEET 1.1

HISTORY OF ELECTRICITY

In 600 B.C, Thales a Greek philosopher accidentally discovered static electricity.

He saw that his garments have bits

of straw and hair. So, Thales

decided to rub his garments with an

amber stone. He was surprised

because the pieces of hair and straw

attract on the stone, the amber

became electrified and it attracted

the pieces of straw. Thales wrote the

incident and did not do anything

about it because he could not

explain the mystery. He did not know he discovered static electricity.

In 1600, William Gilbert, an English Physician

was able to put an electrical charged on the

objects by means of friction or rubbing. He

observed that when the two material rubbed

together, it will receive an opposite charges, that

is, one object got a positive charge and the other

a negative charge. He also noticed that two

oppositely charged materials attract each other.

Gilbert experiment was a re-discovery of static

electricity, the word static means at rest. The

Greek word for amber stone is “ELEKTRON” and

so the term electricity came about.

Figure 1.1: Benjamin Franklin while doing his experiment about electricity in lightning

Figure 1.2: William Gilbert, English Physician


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GREAT PERSONS WHO INVOLVED IN THE DISCOVERY OF ELECTRICITY:


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SOURCES OF ELECTRICITY

Friction – It is a static electricity which is generated by

rubbing two materials. By rubbing any material and

putting it on a light object, the object will intact with the

rubbed material so that, static electricity will produce

Chemical action – It is a great deal of the world’s electricity

produced by batteries. These devices generate a different potential

means of chemical action. It is also a process that leads to the

transformation of one set of chemical substances to another.

Heat action –Two dissolution metals bonded together

in a junction when heated, exhibits a difference of

potential. Such bond is called thermocouple. The trip

of an iron wire, for example, may be welded to that of a

copper wire. When, this junction is heated, the iron

wire shows a positive charge and the copper wire has

a negative charge. Electricity generated by heat action

is called thermoelectric.

Figure 1.3: Friction on balloon

Figure 1.4: Battery, an example of chemical

reaction

Figure 1.5: Thermocouple

http://en.wikipedia.org/wiki/Chemical_substance


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Light action – Photo cells are semi-conduction

devices which convert light electrical energy

directly into electrical energy. Either sunlight or

artificial illumination may be employed. This

action is due to the ability of lights energy to

free electrons from the atoms of the semi-

conductor material. This process is called

photo-electricity.

Pressure – It is a difference of potential

appears across the face of certain crystal

such as quarts, when they are squeezed

or stretched. This is called piezo-

electricity. Piezo- electricity is the electric

charge that accumulates in certain solid

materials in response to applied

mechanical stress. The word

piezoelectricity means electricity

resulting from pressure.

Mechanical action – All electricity in large useful

amount is at present produced by rotating

machines working with the use of magnets. These

machines, known as generator, are turned by water

power, gas engines or steam engines and

sometimes by electric motor.

Figure1.6: Sun, one of the source of light action

Figure 1.7: Piezoelectricity on a lighter

Figure 1.8: Electric Generator

http://en.wikipedia.org/wiki/Stress_(physics)

http://en.wikipedia.org/wiki/Electric_charge

http://en.wikipedia.org/wiki/Electric_charge


Figure 1.10: Bataan nuclear power plant

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MECHANICAL POWER PLANTS THAT PRODUCES ELECTRICAL ENERGY:

Hydropower is an energy obtained from flowing water. Energy in water can be

harnessed and used in the foot motive

energy or temperature differences. The

most common application is the dam.

Power produced by the fall of water from

a higher to a lower level and extracted by

means of waterwheels or hydraulic

turbines. Hydro-power is a natural

resource available wherever a sufficient

volume of steady water flow exists.

Nuclear Power is the method in which

steam is produced by heating water

through a process called nuclear fission.

In a nuclear power plant, a reactor

contains a core of nuclear fuel, primary

enriched uranium. When atoms of

uranium fuel are hit by neutrons they

fission (split), releasing heat neutrons.

Nuclear power is an electrical power

produced from energy released by

controlled fission or fusion of atomic

nuclei in a nuclear reaction. Mass is

converted into energy and the amount of released energy greatly exceeds that from

chemical processes such as combustion.

Figure 1.9: Magat dam Hydro power plant


Figure 1.12: Wind Power Plant in Ilocos

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Solar Power is a power derived from

the energy of the sun. A radiant energy

produced in the Sun as a result of

nuclear fusion reactions. It is

transmitted to the earth through space

by electromagnetic radiation in quanta

of energy called photons which interact

with the earth’s atmosphere and

surface.

Wind Power is the kinetic energy of

wind or the extraction of this energy

by wind turbines. Windmill machine

converts wind into useful energy. This

energy is derived from the force of

wind acting on oblique blades or sails

that radiate from a shaft. The turning

shaft may be connected to machinery

used to perform such work as milling

grain, pumping water, or generating

electricity. When the shaft is

connected to a load, such as a pump, the device is typically called a windmill. When it is

used to generate electricity, it is known as a wind turbine generator.

Fossil Fuel Power Plant(FFPP) – (also

known as steam electric power plant in the

Figure 1.11: Solar powered houses in Masbate


Figure 1.14: Palinpinon geothermal power plant in Valecia, Negros Oriental

Figure 1.15: Tidal Power Station in France

Figure 1.13: Masinloc Coal Power Plant

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US, thermal power plant in Asia, or power station in UK). The most common source of

energy is fossil fuel. Fossil fuels include coal, oil, and natural gas.

Fossil fuel is formed from the remains of plant and animals which live thousands of

years ago. The burning of that fossil fuel provides energy which can be used to

generate electricity.

Geothermal Power comes from heat

energy buried beneath the surface of

the earth. In some areas of the

country, enough heat rises close to

the surface of the earth to heat

underground water into steam which

can be tapped for use in steam-

turbine plants.

Tides is another kind of energy that

involves water. Ocean tides can be used to

turn turbines to generate electricity. For this

to be possible, a dam must be built across

the month of a bay. Water then in trapped

behind the dam at the high tide. At the low

tide, the water is allowed to run out through

the dam and used to turn on electrical

generator.


ELECTRON’S THEORY AND PRINCIPLES


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Electricity is a property of

the basic particle of matter which,

like an atom, consists of proton,

electron and neutron. The

electron is the negatively charged

particle of an atom which is

sometimes referred to as the

negatively charge of electricity.

On the other hand, the proton is

the positively charged particle of

an atom which is sometimes

referred to as the positively

charge of electricity that weighs

about 1850 times as much as the electron. The neutron is the particle which is not

electrically charged and weighs slightly more than proton.

MOLECULAR THEORY

• All matters are made up of molecules.

• All molecules are made up of atoms.

• All the atoms contain neutron, electrons and protons.

• The entire neutron is neutral, hence, neither positively nor negatively charged.

• The electron of an atom of any substance could be transferred to another atom.

THE ELECTRON THEORY

The electron theory states that all matter is made up of electricity. Matter is

anything which has weight, occupies space is made up of molecules, of which millions

of different kinds. The molecules in turn, are made up of atoms of which are the

smallest units of the several elements and of a limited number. All atoms believed to be

composed of electrons, which are minute particle of negative electricity normally held in

place in each atom by positively charged particles called nucleus. Thus, the electron,

Figure 1.15: Structure of an atom


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which are interlocked in the atoms, are constantly revealing at great speeds in orbits

around positive nuclei. In a normal atom, the amount of negative electricity of the

electrons is exactly neutralized by an equal amount of opposite or positive electricity of

the nucleus. Thus, a normal atom exhibits no external sign of electrification.

STRUCTURE OF AN ATOM

All of the atoms consist of two basic

parts: a body at the center of the atom called

the nucleus, orbiting around the nucleus.

Atoms may have more than one orbiting

electron, but each atom contains only one

nucleus.

The attraction between the nucleus and the electron is called electrostatic force,

which holds the electron in an orbit. Bodies

that attract each other in this special

electrostatic way are described as charged

object. The electron carries the negative

charge (-), while the nucleus carries the

positive charge (+).

The positive charge of the nucleus is

due to the particles called protons which are

Electron

Nucleus

Nucleus

ElectronElectron force holds the electron orbit.

Nucleus Proton

Electron

Figure 1.16: Nucleus and Electron

Figure 1.17: Electrostatic Force


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found inside the nucleus and have a positive charge equal to the electron’s negative

charge.

LAW OF ELECTROSTATICS

The protons and electrons attract each other inside the atom. It has been known

that by nature, unlike charges (like the positive protons and negative electrons) attract

each other while like charges repel each other; meaning, electrons and protons repel

each other’s protons.

Figure 1.20: Like charges repel each other

Figure 1.21: Unlike charges attract each other

Figure 1.18: A diagram showing proton


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EXERCISES 1.1

Direction: Identify the following. Write your answers on the space provided.

____________ 1. An English Physician was able to put an electrical charged on the

objects by means of friction or rubbing.

____________ 2. It is a static electricity which is generated by rubbing two materials.

____________ 3. It is the negatively charged particle of an atom which is sometimes

referred to as the negatively charge of electricity.

____________ 4.It is the positively charged particle of an atom which is sometimes

referred to as the positively charge of electricity that weighs about 1850 times as much

as the electron.

____________ 5.It is the energy extracted from the heat generated by natural

concentrations of hot water and steam in the earth’s interior.

____________ 6. It is known as the steam electric power plant in the US, thermal power

plant in Asia, or power station in UK.

____________ 7. It states that all matter is made up of molecules.

____________ 8. It is the attraction between the nucleus and the electron.

____________ 9.It is a difference of potential appears across the face of certain crystal

such as quarts, when they are squeezed or stretched.

____________ 10.The Greek word for amber stone.


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PERFORMANCE SHEET 1.1

ATTRACTION BY A CHARGE OBJECT

Materials

Comb Small pieces of paper Dry woolen cloth Ballon Wall Dry fine sand

Working Drawing

COMB BALLOON

Procedure

1. Put the tip of your comb near the small pieces of paper. What happened?


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2. Rub your comb briskly with a dry woolen cloth.

3. Put again the tip of your comb towards some tiny pieces of paper. What happened to the

tiny pieces of paper? Compare your observation with the second step.

4. Rub the inflated balloon with the woolen cloth.

5. Put the balloon against the wall. Why did the balloon stick on the wall? Do you think the

same will happen without rubbing the balloon?

6. Rub the balloon with the woolen cloth again.

7. Hold the balloon over very dry fine sand. What happened to the sand as you brought the

balloon near to it? What kind of electricity was produced when you rubbed two materials of

different kind?

PRINCIPLES OF ELECTRICITY COMPARISON OF AND DC

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UNIT II

COMPARISON OF AC AND DC

Electric Current is the flow or rate of flow of electric force in the conductor. A

current will only flow if a circuit is formed comprising a complete loop and contains all

the following required components: Source of voltage, a closed loop of wiring, an

electric load and a means of opening and closing the circuit.

Electric current in a wire, where the charge carriers are electrons, is a measure

of the quantity of charge passing any point of the wire per unit of time. In alternating

current the motion of the electric charges is periodically reversed; in direct current it is

not.

Although it is electrons which are the mobile charge carriers which are

responsible for electric current in conductors such as wires, it has long been the

convention to take the direction of electric current as if it were the positive charges

which are moving.

AC is short for alternating current. This means that the direction of current flowing

in a circuit is constantly being reversed back and forth. This is done with any type of AC

current/voltage source. The electrical current in your house is alternating current. This

comes from power plants that are operated by the electric company. Those big wires

you see stretching across the countryside are carrying AC current from the power plants

to the loads, which are in our homes and businesses.

Direct current (DC) is the unidirectional flow of electric charge. Direct current is

produced by sources such as batteries, thermocouples, solar cells, and commutator-

type electric machines of the dynamo type.

In the end of the chapter, you must be able to:

1. Understand the meaning of Electric Current

2. Classify Direct Current to Alternating Current

3. Analyze the Origins of AC and DC Current

4. Compare AC to DC


Figure 2.2: Sine wave of AC and DC

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CLASSIFICATION OF ELECTRIC CURRENT

Direct Current (DC)

The DC electricity, flows in

one direction. The flow is said to

be from negative to positive. The

normal source of DC electricity is

the dry cell or storage battery.

Alternating Current (AC) or

Voltage

The AC electricity

constantly reverses its direction of flow. It is generated by machine called generator.

This type current is universally accepted because of its unlimited numbers of

applications with its advantages.

ORIGINS OF AC AND DC CURRENT

A magnetic field near a wire

causes electrons to flow in a single

direction along the wire, because

they are repelled by the negative

side of a magnet and attracted

toward the positive side. This is

how DC power from a battery was

born, primarily attributed to Thomas

Edison's work.

AC generators gradually

replaced Edison's DC battery system because AC is safer to transfer over the longer

city distances and can provide more power. Instead of applying the magnetism along

the wire steadily, scientist Nikola Tesla used a magnet that was rotating. When the

Figure 2.1: Direct Current and Alternating Current


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magnet was oriented in one direction, the electrons flowed towards the positive, but

when the magnet's orientation was flipped, the electrons turned as well.

Electricity flows in two ways; either in alternating current (AC) or in direct current

(DC). Electricity or 'current' is nothing more than moving electrons along a conductor,

like a wire, that have been harnessed for energy. Therefore, the difference between AC

and DC has to do with the direction in which the electrons flow. In DC, the electrons flow

steadily in a single direction, or "forward." In AC, reverses its polarity on each

alternation and reverses its direction of flow for each alternation. The AC goes through

one positive loop and one negative loop to form one complete cycle that is continuously

repeated.

Advantages of Alternating Current (AC)

• It is easily produced.

• It is cheaper to maintain.

• It could be transformed into higher voltage.

• It could be distributed to far distance with low voltage drop.

• It is more efficient compared to the direct current.

Aspects of Comparison Alternating Current Direct Current

Amount of energy that can

be carried

Safe to transfer over

longer city distances and

can provide more power.

Voltage of DC cannot

travel very far until it

begins to lose energy.

Cause of the direction of

flow of electrons

Rotating magnet along the

wire.

Steady magnetism along

the wire.

Frequency The frequency of

alternating current is 50Hz

or 60Hz depending upon

the country.

The frequency of direct

current is zero.


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Direction It reverses its direction

while flowing in a circuit.

It flows in one direction in

the circuit.

Current It is the current of

magnitude varying with

time

It is the current of constant

magnitude.

Flow of Electrons Electrons keep switching

directions - forward and

backward.

Electrons move steadily in

one direction or 'forward'.

Obtained from A.C Generator and mains. Cell or Battery.

Passive Parameters Impedance. Resistance only

Power Factor Lies between 0 & 1. is always 1.

Types Sinusoidal, Trapezoidal,

Triangular, Square.

Pure and pulsating.

Table 2.1: Comparison of AC and DC Electricity

A circuit operating at increased voltage, has a lower power loss, power voltage

drop, and economically constructed for using smaller copper wires. On transmission

and distribution line, power loss is the most important problem to resolve. This is the

main reason why Alternating Current AC gained more favor and acceptance during the

middle part of the 19th century.

What is special about AC electricity is that the voltage can be readily changed,

thus making it more suitable for long-distance transmission than DC electricity. But also,

AC can employ capacitors and inductors in electronic circuitry, allowing for a wide range

of applications.

The major advantage that AC electricity has over DC electricity is that AC

voltages can be readily transformed to higher or lower voltage levels, while it is difficult

to do that with DC voltages.

Since high voltages are more efficient for sending electricity great distances, AC

electricity has an advantage over DC. This is because the high voltages from the power

station can be easily reduced to a safer voltage for use in the house.


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EXERCISES 2.1

Directions: Identification. Put AC when it is Alternating Current or DC if it is Direct

Current. Put your answers on the space provided.

__________ 1.It is electricity constantly reverses its direction of flow.

__________ 2.The flow is said to be from negative to positive.

__________ 3.It could be distribution to far distance with low voltage drop.

__________ 4. It cannot travel very far until it begins to lose energy.

__________ 5.It is the current of constant magnitude.

__________ 6.This type current is universally accepted because of its unlimited

numbers of applications with its advantages.

__________ 7. The frequency of this current is zero.

__________ 8.Rotating magnet along the wire.

__________ 9.It is cheaper to maintain.

__________ 10.Pure and pulsating.


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ACTIVITY SHEET 2.1

Direction: Compare the following by your own words. Use the space below for the

answer.

Five Comparisons of Alternating Current to Direct Current

ALTERNATING CURRENT DIRECT CURRENT

PRINCIPLES OF ELECTRICITY THE OHM’S LAW

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UNIT III

THE OHM’S LAW

In 1926, a German Scientist named George Simon Ohm (1789-1854) discovered

the relationships between the Current, Voltage and Resistance. It is now referred as the

Ohms Law which stated that:

“The higher the voltage, the larger the current, and the higher the resistance, the

lower the current”.

Probably the most important mathematical relationship between voltage, current

and resistance in electricity is something called “Ohm’s Law”. This formula is used to

calculate electrical values so that we can design circuits and use electricity in a useful

manner.

This equation indicates the two variables that would affect the amount of current

in a circuit. The current in a circuit is directly proportional to the electric potential

difference impressed across its ends and inversely proportional to the total resistance

offered by the external circuit and an increase in the resistance of the load by a factor of

two would cause the current to decrease by a factor of two to one-half its original value.

Ohm's law is a generalization from many experiments that have shown that

current is approximately proportional to electric field for most materials. Ohm's law is

one of the basic equations used in the analysis of electrical circuits. It applies to both

metal conductors and circuit components (resistors) specifically made for this behavior.

In the end of the unit, you must be able to:

1: Identify the introduction of the Ohm’s Law

2: Express the formulas of Ohm’s Law

3: Summarize the Ohm’s Law


Figure 3.1 Ohm’s Law triangle

22

______________________________________________________________________________________________


Ohms Law is the relationship between the current, voltage and resistance is

presented in the equations below.

I is the current through the conductor in units of amperes, V is the potential difference

measured across the conductor in units of volts, and R is the resistance of the

conductor in units of ohms. Ohm's law states that the R in this relation is constant,

independent of the current.

OHM’S LAW CAN BE EXPRESSED IN

MATHEMATICAL EQUATION (See fig. 3.1)

Voltage (volts)

To find the Voltage (E or V), Current must be multiply to

the resistance.

Current (ampere)

Current is equal to the voltage over resistance.

Resistance (ohm)

To find the resistance, the given voltage must be divided to the given current.

V=I x R

I=_V_

R

R=_V_

I

http://en.wikipedia.org/wiki/Ohm

http://en.wikipedia.org/wiki/Electrical_resistance

http://en.wikipedia.org/wiki/Volt

http://en.wikipedia.org/wiki/Ampere


23

______________________________________________________________________________________________

In the figure above, it shows how the Ohm’s Law triangle uses.

On the right side, it shows that V is highlighted. When we want to solve the

voltage, we must put our hand to the V then solve the remaining letter in the triangle. It

shows that I and R were between each other. So, the solution to find the V is I multiplied

to R.

On the 2nd triangle, it shows above that Iis highlighted. V is on the top of R, so to

find I, V must be divided to R.

On the last triangle, R is highlighted. V is on the top of I. So, to find R, V must be

divided to I.

Figure 3.2: Ohm’s Law triangles and formulas


24

______________________________________________________________________________________________

ILLUSTRATION 3.1

Determine that the flow of the current having a resistance of 10 ohms on a 220 volts

current supply.

ILLUSTRATION 3.2

Determine the given voltage having a current of 12 amperes and a resistance of 5

ohms.

GIVEN:

R= 10 ohms

V= 220 volts

I=?

SOLUTION:

I = _V_ R

I=_220_ 10

I= 22 Amperes

GIVEN:

I= 12 amps

R= 5 ohms

V=?

SOLUTION:

V= IR

V=12(5)

V= 60 Volts

PRINCIPLES OF ELECTRICITY THEOHM’S LAW

25

_______________________________________________________________________________________________

ILLUSTRATION 3.3

A circuit has a voltage of 230 volts and the current flows at 15 amperes. Determine the

resistance for the said circuit.

SUMMARY OF THE OHM LAW FORMULAS:

Voltage = Current x Resistance

V = I x R

Current = _Voltage_

Resistance

I = _V_

R

Resistance = _Voltage_

Current

R = _V_

I

Power = Voltage x Current

P= V x I

GIVEN:

V= 230 volts

I= 15 amps

R=?

SOLUTION:

R = _V_ I

R = _230_ 15

R= 15.33 Ohms


26

_______________________________________________________________________________________________

P= I² x R I = _P_ V = _P_ R = _P_ V I I²

P = V² I =√ PR V=√PxR R = V²

R P

Figure 3.4 Ohms Law Pie Chart

Figure 3.3: Further manipulations of other ohm’s law data


27

_______________________________________________________________________________________________

EXERCISE 3.1

Direction: Express the following equations. Write the solution on the space provided

then the answer in the underline.

1. R = 20 Ohms

V = 220 Volts

I = ________

2. V = 400 Volts

I = 5 Amps

R = ________

3. I = 39 Amps

R = 20 Ohms

V= ________

4. V = 530 Volts

I = 13 Amps

R = ________

5. I = 730 Volts

R= 321 Ohms

V= ________

SOLUTION:

PRINCIPLES OF ELECTRICITY ELECTRICAL CIRCUITS

28

______________________________________________________________________________________________

UNIT IV

ELECTRICAL CIRCUITS

Electrical Circuits is serving as the pathway of the current to the load. If there is a

circuit, the electricity will be flow freely until it reaches the load. A circuit is simply a

closed loop through which charges can continuously move.

The interconnection of various electric elements in a prescribed manner

comprises as an electric circuit in order to perform a desired function. The electric

elements include controlled and uncontrolled source of energy, resistors, capacitors,

inductors, etc. Analysis of electric circuits refers to computations required to determine

the unknown quantities such as voltage, current and power associated with one or more

elements in the circuit.

The circuit demonstrated by the combination of battery, light bulb and wires

consists of two distinct parts: the internal circuit and the external circuit. The part of the

circuit containing electrochemical cells of the battery is the internal circuit. The part of

the circuit where charge is moving outside the battery pack through the wires and the

light bulb is the external circuit.

A circuit component can be arranged in several ways but with two fundamental

types of connections like series circuit and parallel circuit.

In the end of the chapter, you must be able to:

1. Analyze the meaning of electrical circuits.

2. Identify the parts of a complete circuit.

3. Classify the types of electrical circuits.


Figure 4.1: Complete Circuit

29

______________________________________________________________________________________________


PARTS OF A COMPLETE CIRCUIT

In order that electricity can be better understood different parts or components of

a complete circuit must be known

well. First, the electrical circuit

should have a source of power

where the electric current starts to

flow. The power source can be a

generator, storage cell one or

more cells. Second, a path such

as electrical wires is needed in

order that electricity from the

source can be transmitted. Third,

there should be a current-

consuming device or appliance

that will consume or use electricity.

And lastly, a control or switch that will cut off the flow of current, when the appliance will

not be in use. All the requirements mentioned are important in order to have complete

electrical circuit. The absence of one will not make a complete electric circuit.

Figure 4.2: Schematic Diagram of a complete circuit


30

______________________________________________________________________________________________

SERIES CIRCUITS

A series circuit is a circuit in which

resistors are arranged in a chain, so the

current has only one path to take. The

current is the same through each resistor.

The total resistance of the circuit is found

by simply adding up the resistance values

of the individual resistors:

Equivalent resistance of resistors in

series: R = R1 + R2 + R3 +...

A series circuit is shown in the diagram above. The current flows through each resistor

in turn. If the values of the three resistors are:

With a 10 V battery, by V = I R the total current in the circuit is:

I = V / R = 10 / 20 = 0.5 A. The current through each resistor would be 0.5 A.

Figure 4.3: Pictorial Diagram of a Complete Circuit

Figure 4.4: Series Circuit


Figure 4.5: Parallel Circuit

31

______________________________________________________________________________________________

Laws of series circuit:

• The total resistance in the circuit is the sum of all individual resistances.

• The current throughout the circuit is the same.

• The total voltage in the circuit is equal to the sum of the individual voltages.

PARALLEL CIRCUITS

A parallel circuit is a circuit in

which the resistors are arranged with

their heads connected together, and their

tails connected together. The current in a

parallel circuit breaks up, with some

flowing along each parallel branch and

re-combining when the branches meet

again. The voltage across each resistor in

parallel is the same.

The total resistance of a set of resistors

in parallel is found by adding up the

reciprocals of the resistance values, and

then taking the reciprocal of the total:

Equivalent resistance of resistors in parallel: 1 / R = 1 / R1 + 1 / R2 + 1 / R3 +...

A parallel circuit is shown in the diagram above. In this case the current supplied

by the battery splits up, and the amount going through each resistor depends on the

resistance.

Laws of parallel circuit:

• The voltage is the same across each branch.

• The total current is the sum of all the current in each circuit.

• The total resistance is less or approximately equal to the smallest resistive branch


32

______________________________________________________________________________________________

EXERCISES 4.1

I. Directions: Identify the following. Write your answers on the space provided

____________ 1. is a circuit in which resistors are arranged in a chain, so the current has only one path to take.

____________ 2. is a circuit in which the resistors are arranged with their heads connected together, and their tails connected together.

____________ 3. Use to cut the flow of current in a circuit.

____________ 4.The consumer of the power in the circuit.

____________ 5. The pathway in which current is being flow.

II. Direction: Identify the following parts of a simple circuit.


33

______________________________________________________________________________________________


CONNECT 2 BULBS IN SERIES USING SPST SWITCH

Supplies and Materials

2 pieces 1.5 batteries

2 pieces bulb

1 meter wire

2 pieces socket

1 piece switch

Electrical tape

Tools

Pliers

Screw drivers

Procedure

1. Prepare all tools and materials needed.

2. Construct an electrical circuit and connect two bulbs in series. Close the circuit and

observe the brightness of the light.

3. Add one more bulb in the set up. Describe the change in the brightness of the bulb.

In which setup do the bulbs light more brightly?

4. Unscrew one of the bulbs and close the circuit. Observe what happens.

5. Trace the flow of the electric current. How are the bulbs arranged in a series circuit?

SCHEMATIC DIAGRAM


34

______________________________________________________________________________________________


CONNECT 3 BULBS IN PARALLEL WITH SPST SWITCH

Supplies and Materials

2 pieces 1.5 batteries

3 pieces bulb

1 meter wire

3 pieces socket

1 piece switch

Electric tape

Tool

Pliers

Screw drivers

Procedure

1. Prepare all the tools and materials needed.

2. Connect two sockets with bulbs to a dry cell. Observe the brightness of their lights.

3. Add one more bulb in the setup. Observe the brightness of their light. Do the adding

bulbs in the setup affect the brightness of the bulb?

4. Unscrew one bulb in the set up and close the circuit.

5. Unscrew another bulb in the setup. Why does the turning off of one or two bulbs

break the circuit?

6. Trace the path of the electric current flow beginning from the source. How many

paths can the electric current take before returning to the source?

SCHEMATIC DIAGRAM


35

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UNIT V

ELECTRICAL POWER AND ENERGY

Power and energy is frequently interchangeably used. Power is the technical

term for the common word work. And work, is the product of power and time. A power

station is a place where other forms of energy - coal, gas, potential energy in water and

nuclear energy - are turned into electrical energy for transmission to places that use

electrical energy.

Electrical power is conceptually simple. Consider a device that has a voltage

across it and a current flowing through it. Electric power has become increasingly

important as a way of transmitting and transforming energy in industrial, military and

transportation uses. Electric power systems are also at the heart of alternative energy

systems, including wind and solar electric, geothermal and small scale hydroelectric

generation.

Energy is vital for all living – beings on earth. Modern life style has further

increase its importance, since a faster life means faster transport, faster communication,

and faster manufacturing processes. All these lead to an increase in energy required for

all those modern systems.

In the end of the chapter, the student must be able to:

1. Understand the meaning of electrical power

2. Express the equations of the power law


36

______________________________________________________________________________________________


Electrical power is the rate at which energy is used or the rate at which work is

done. The measuring unit of electrical power is watt, named after Scottish inventor and

mechanical engineer James Watt. The power input to any electrical devices having a

resistance R with the current I is expressed in the following equations:

Where:

P in Watts

V in Volts

R in Ohms

I in Ampere

Energy is one of the basic quantitative properties describing a physical system

or object's state. Energy can be transformed among a number of forms that may each

manifest and be measurable in differing ways or simply it is the capacity to do work.

Energy or Work = Power x Time

POWER IN ELECTRIC CIRCUIT

The measuring unit used in electric power is the watt. When it is multiplied in

1000, the product is called kilowatt. Therefore 1000 watt is equals to 1 kilowatt. The

power has several forms: the horsepower, thermal power and candle power.

Thermal power is the power measured heat, i.e. an electric heater. Horsepower

is the power measured of on electric motor that produces mechanical power, and

candle power is the measured power of light bulb that produces both heat and light.

The power input to any electrical devices having the current with the resistance is

expressed in the following equations:

By Ohm’s Law:

V = IR

P = I² R

P = VI

PRINCIPLES OF ELECTRICITY ELECTRICAL POWER AND ENERGY

37

_______________________________________________________________________________________________

EXERCISES 5.3

I. Directions: Identify the following. Write your answer on the space provided.

___________1. It is the rate at which energy is used or the rate at which work is done.

___________2. It is the capacity to do work.

___________3. The measuring unit used in electric power.

II. Directions: Fill in the blanks. Complete the following formulas for power and energy.

1. Power = ____________ x Voltage

2. Energy or Work = _____________ x Time

III. Directions: Compute for the problem regarding electrical power.

1. An electric iron is rated 220VAC operating normally and also gained 3.2A. How much electrical power is consumed?

PRINCIPLES OF ELECTRICITY CONDUCTORS AND INSULATORS

38

_______________________________________________________________________________________________

UNIT VI

CONDUCTORS AND INSULATORS

Conductors and insulators have a great contribution in building wiring installation.

Because of this, we have already now wires and cables. There are the components of a

good pathway of current.

The behaviour of an object that has been charged is dependent upon whether

the object is made of a conductive or a nonconductive material. Conductors are

materials that permit electrons to flow freely from particle to particle. An object made of

a conducting material will permit charge to be transferred across the entire surface of

the object. If charge is transferred to the object at a given location, that charge is quickly

distributed across the entire surface of the object.

In contrast to conductors, insulators are materials that impede the free flow of

electrons from atom to atom and molecule to molecule. If charge is transferred to an

insulator at a given location, the excess charge will remain at the initial location of

charging. The particles of the insulator do not permit the free flow of electrons;

subsequently charge is seldom distributed evenly across the surface of an insulator.

In the end of this unit, you must be able to:

1. Understand the meaning of conductors

2. Identify good conductors to fair conductors

3. Understand the meaning of insulators

4. Classify the insulators, its class and its types


Figure 6.1: Copper, an example of conductor

39

_______________________________________________________________________________________________


CONDUCTORS

Conductor is the electrical

material used which electrons can

move easily and free. By

describing this conductor, it is a

metal with a very low of

resistance. It is a body carries

when electric current transmit.

Therefore, conductors have

different conductivities. Actually,

the copper prefer to the many

uses, because of its superior

strength in both hot and cold weather. There are two classes of conductors, the good

conductors and the fair conductors, it listed in the first column in the order of decreasing

conductivity in the Table 1.

Good Conductors Fair Conductors

Silver Charcoal and Coke

Copper Carbon

Aluminium Acid solutions

Zinc Sea water

Brass Saline solutions

Platinum Metallic ores

Iron Living vegetables

Nickel Substance

Tin Moist Earth

Lead

Table 6.1: Good and Fair Conductors


Fig. 6.2: A Rubber Insulator

40

_______________________________________________________________________________________________

INSULATORS

Insulators are also electrical

materials that resist the flow of electric

current. In the other means, it is a

substance that does not carry electric

current. It described which the

conducting wire is covered with an

insulating substances or insulating

supports to protect from electric shock.

So that, we need good insulations

which is help to stop the electric current

from being lost or leaking away.

Therefore, we will be concerned in the more common insulators used in electrical work.

Of the insulators listed, the best insulator is dry air but we commonly use is rubber

which has extremely high resistance. PVC a Polyvinylchloride is also insulating

substance widely used, a plastic that it covers to the how many of conducting wire

insulated. It listed below, the kinds of insulators.

Insulators

Slate

Oils

Porcelain

Dry paper

Silk

Sealing wax

Ebonite

Mica

Glass

Dry air

Table 6.2: Various kinds of Insulators


41

_______________________________________________________________________________________________

Substances are used as insulators in practical electrical work. It is classified in

four classes of insulation. Such as follows,

Class A Insulation

It is consists of (a) cotton, silk, paper, and materials

similar to paper when impregnated or immersed in an

insulating liquid, (b) molded or laminated materials with

cellulose filler, phenol resins, or similar resins, (c) films

or sheets of cellulose acetate or similar cellulose

products and (d) varnishes or enamels applied to

conductors.

Class B Insulation

It consists entirely of mica, or fiber-glass, all

with a binder.

Class C Insulation

It consists entirely of porcelain, glass, quartz, or

similar materials. It is commonly used in high voltage

intensities like posts, electrical grids and power

generator plants.

Figure 6.3: Class A Insulation in a socket

Figure 6.4: Mica Tube, example of Class B

Figure 6.5: Porcelain insulation


Figure 6.6: Pin type insulators

Figure 6.7: Suspension type insulators

42

_______________________________________________________________________________________________

TYPES OF INSULATORS

There are several types of insulators but the most commonly used are pin type,

suspension type, strain insulator and shackle insulator.

Pin type Insulators

The pin type insulator is secured to the

cross-arm on the pole. There is a groove on the

upper end of the insulator for housing the

conductor. The conductor passes through this

groove and is bound by the annealed wire of the

same material as the conductor.

Pin type insulators are used for transmission and

distribution of electric power at voltages up to 33

kV. Beyond operating voltage of 33 kV, the pin type insulators become too bulky and

hence uneconomical.

Suspension Type

It consists of a number of

porcelain discs connected in series by

metal links in the form of a string. The

conductor is suspended at the bottom

end of this string while the other end of

the string is secured to the cross-arm of

the tower. Each unit or disc is designed

for low voltage, say 11 kV. The number of

discs in series would obviously depend

upon the working voltage. For instance, if the working voltage is 66 kV, then six discs in

series will be provided on the string.


Figure 6.8: Strain insulators

Figure 6.9: Shackle insulators

43

_______________________________________________________________________________________________

Strain Insulators

Is an electrical insulator that is

designed to work in mechanical tension

(strain), to withstand the pull of a

suspended electrical wire or cable.

They are used in overhead electrical

wiring, to support radio antennas and

overhead power lines. A strain insulator

may be inserted between two lengths of

wire, to isolate them electrically from

each other while maintaining a mechanical connection, or where a wire attaches to a

pole or tower, to transmit the pull of the wire to the support while insulating it electrically.

Strain insulators were first used in telegraph systems in the middle of 19th century.

Shackle Insulators

The shackle insulators were used as strain

insulators, but now a day, they are frequently used for

low voltage distribution lines. Such insulators can be

used either in a horizontal position or in a vertical

position. They can be directly fixed to the pole with a

bolt or to the cross arm.


44

_______________________________________________________________________________________________

EXERCISES 6.1

Directions: Identify the correct answer. Write the answer on the space provided.

__________ 1. An electrical material used which electrons can move easily and freely.

__________ 2.An electrical material that resist the flow of electric current.

__________ 3. What is the PVC mean?

__________ 4. Give at least three good conductors we commonly used.

__________ 5. It is a type of insulators used for transmission and distribution of electric

power at voltages up to 33kV.

__________ 6. An insulator material has extremely high resistance.

__________ 7. The wire covered insulating substances which supports to protect from

what common condition.

__________ 8. A type of insulators which is consists of a number of porcelain discs

connected in series by metal links in the form of a string.

_________ 9. A type of insulator designated to work in mechanical tension.

_________ 10. A type of insulator frequently used for low voltage distribution lines.


45

_______________________________________________________________________________________________

ACTIVITY SHEET 6.1

CONDUCTORS AND INSULATORS

Directions: Look at the pictures below. Write Insulators if a material that does not allow

electricity to pass through it or Conductors if the material that allows electricity to pass

through it in the space provided.

1. ______________________ 5. ______________________

2. ______________________ 6. ______________________


46

_______________________________________________________________________________________________

3. ______________________ 7. ______________________

4. ______________________ 8. ______________________

PRINCIPLES OF ELECTRICITY WIRES AND CABLES

47

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UNIT VII

WIRES AND CABLES

Wires and cables are commonly used in electrical circuits. It is used as the

pathway of current to flow free in the system. In this unit, the difference between wires

and cables will be tackle about.

Wire and cable products are important part of all industries. Whether one owns a

small machine shop or runs a big industry, he must know from where to get wires and

cables.

Wires and cables have many uses, ranging from electrical equipment and jewelry

to chain-link fences and hay bales. While the same types of wire cannot be used for the

multiplicity of purposes which mankind has found for wire, all of it, regardless of

function, has a similar form and shares manufacturing methodologies.

Electrical wires and cables are almost always insulated, differentiating it from

other types of wire. It is also made of copper because of the many advantages copper

provides. Other wire is most often made of steel, except for that used in jewelry, which

is silver or gold. The insulation on electrical wire is necessary to avoid shock and short-

circuiting one wire to another.

In many cases, specific wires and cables have been created for common

applications. These types of wire or cable should be purchased for use in these

applications, rather than trying to find another wire which can be used to do the same

thing.

In the end of the chapter, the student must be able to:

1. Understand the meaning of wires

2. Identify the types of wires

3. Analyze the meaning of cables

4. Classify the types of insulators


48

______________________________________________________________________________________________


WIRES

Wire is a length of such

material either of a single filament or

of several filaments woven or twisted

together and usually insulated with a

dielectric material, used as conductors

of electricity. Generally, it is made of

copper and aluminum, most of wire is

a round conductor. It is help to

transmit electric current from one

place to another.

There are two classes of wire the solid and the stranded wire. Solid wire is

consists of a single, solid round conductor, while the stranded wire has several non-

insulated, thin round conductors, bundled or woven together to form a single, larger

round conductor.

TYPES OF WIRE

Figure 7.1 Wires

Figure 7.2: Solid wire (left) and stranded wire (right)


49

______________________________________________________________________________________________

There are many different types of wires that may be used in electrical wiring

building. See the Table.1 the conductor application.

Trade name Type letter Max. Operating

temp.

Application

provisions

Rubber-covered

Fixture wire, solid

Or 7-strand

RF-1 60 °C

140 ° F

Fixture wiring. Limited

to 300 volts.

RF-2 60°C

140°F

Fixture wiring, and as

permitted in Sec.310-

8

Rubber-covered

Fixture wire,

Flexible stranding

FF-1 60°C

140°F


to 300 volts.

FF-2 60°C

140°F



8

Heat-resistant

Rubber-covered

fixture wire, solid or

7-strand

RFH-1 75 °C

167 ° F


to 300 volts.

RFH-2 75°C

167°F



8

Heat-resistant

Rubber-covered

fixture wire, flexible

stranding

FFH-1 75°C

167°F


to 300 volts.

FFH-2 75°C

167°F


to 300 volts.

Thermoplastic-

covered fixture wire,

solid or stranded

TF 60 °C

140 ° F



8, and for circuits as

permitted in Art. 725

TFF 60°C

140°F



8, and for circuits as Table 7.1: Types of wires (continued)


50

______________________________________________________________________________________________

permitted in Art. 725

Thermoplastic-


flexible stranding

TFN 90℃ Fixture wiring, and as


8

Heat-resistant

thermoplastic-


flexible stranding

TFFN 90℃ Fixture wiring, and as


8

Cotton-covered

heat-resistant fixture

wire

CF 90℃

194℉


to 300 volts.

Asbestos-covered

heat-resistant fixture

wire

AF 150℃

302℉


to 300 volts and

indoor dry locations

Fluorinated ethylene

propylene fixture

wire, solid or 7-

strand

PF

PGF

150℃302℉ Fixture wiring and as


8


propylene fixture

wire

PFF

PGFF

150℃302℉ Fixture wiring and as


8

Silicone rubber

insulated fixture

wire, solid or 7-

strand

SF-1 200℃

392℉


to 300 volts.

SF-2 200℃392℉ Fixture wiring and as


8

Silicone rubber

insulated fixture

wire, flexible

stranding

SFF-1 150℃302℉ Fixture wiring. Limited

to 300 volts.

SFF-2 150℃302℉ Fixture wiring and as


Table 7.1: Types of wires (continued)


51

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8

Heat-resistant-

rubber

RH 75℃

167℉

Dry locations

Heat-resistant-

rubber

RHH 90℃

194℉

Dry locations

Moisture and heat

resistant rubber

RHW 75℃167℉ Dry and wet

locations/ for over

2,000 volts, insulation

shall be ozone-

resistant

Heat-resistant

latex rubber

RUH 75℃ Dry locations

Moisture-resistant

latex rubber

RUW 60℃

140℉

Dry and wet locations

Thermoplastic T 60℃140℉ Dry locations

Moisture resistant

thermoplastic

TW 60℃140℉ Dry and wet locations

Heat-resistant

thermoplastic

THHN 90℃194℉ Dry locations

Moisture and heat-

resistant

thermoplastic

THW 75℃167℉ Dry and wet locations

Moisture and heat-

resistant

thermoplastic

THWN 75℃167℉ Dry and wet locations

Moisture and heat-

resistant cross-

linked thermosetting

XHHW 90℃194℉ Dry locations



52

______________________________________________________________________________________________

polyethylene 75℃167℉ Wet locations

Moisture-heat and

oil-resistant

thermoplastic

MTW 60℃140℉90℃194℉

Wet locations,

machine-tool wiring.

Dry locations.

Machine-tool wiring.

Moisture-heat and

oil-resistant

thermoplastic

THW- MTW 75℃167℉90℃194℉


Special applications

within electric

discharge lighting

equipment. Limited

to1,000 open-circuit

volts or less (size 14-

8 only)

Thermoplastic and

asbestos

TA 90℃194℉ Switch board wiring

only

Thermoplastic and

fibrous outer braid

TBS 90℃194℉ Switch board wiring

only

Synthetic heat-

resistant

SIS 90℃194℉ Switch board wiring

only

Mineral insulation

(metal-sheathed)

MI 85℃185℉250℃

482℉


with type O

termination fittings

For special

application

Silicone-asbestos SA 90℃ Dry locations



53

______________________________________________________________________________________________

194℉

125℃

275℉

For special

application


propylene

FEP

Or

FEPE

90℃194℉200℃392℉

Dry locations

Dry locations-special

applications

Varnished cambric V 85℃185℉ Dry locations only.

Smaller than No.6 by

special permission

Asbestos and

varnished cambric

AVA 110℃

230℉

Dry locations only

Asbestos and

varnished cambric

AVL 110℃230℉ Dry and wet locations

Asbestos and

varnished cambric

AVB 90℃194℉ Dry locations only

Asbestos A 200℃392℉ Dry locations. Only

for leads within

apparatus or within

raceways connected

to apparatus. Limited

to 300 volts.

Asbestos AA 200℃392℉ Dry locations. Only

for leads within

apparatus or within

raceways connected

to apparatus or as

open wiring. Limited Table 7.1: Types of wires (continued)


54

______________________________________________________________________________________________

to 300 volts

Asbestos AI 125℃275℉ Dry locations. Only

for leads within

apparatus or within

raceways connected

to apparatus. Limited

to 300 volts.

Asbestos AIA 125℃275℉ Dry locations. Only

for leads within

apparatus or within

raceways connected

to apparatus or as

open wiring. Limited

to 300 volts

Paper 85℃

185℉

AMERICAN WIRE GAUGE

Usually, most of electricians check

the wire sizes with an American Standard

Wire Gauge. It is a gauge it measure the

diameter of a wire in millimeters (mm) and

inches (in.), it expressed as a whole

number. The higher gauge numbers

correspond with smaller diameters.

Table 7.1: Types of wires

Figure 7.3: An example of measuring tool of AWG


Figure 7.4: Cable

Figure 7.5: Twisted Pair Cable

55

______________________________________________________________________________________________

CABLES

Cable is a special cord designated to

carry electric currents or signals. Simply, it is

a heavy strong rope. An insulated electrical

conductor, a strands or a combination of

electrical conductors insulated from one

another. Maybe either shielded or unshielded.

Shielded are used for such thing as

connecting a cd player or tape desk to an

amplifier while unshielded are used for such

things as extension cords, telephone cords, and doorbell circuits.

THERE ARE DIFFERENT TYPES OF CABLES, SUCH AS FOLLOWS:

Twisted Pair Cable

As the name suggests, two

conductors are twisted together to make

a Twisted Pair Cable. One acts as a

forward and the other as a return

conductor in any circuit. Since both the

conductors are insulated and twisted

within a jacket, this design reduces

interference from external sources. This

cable is specifically intended to carry signals and was used in early telephonic systems

Coaxial Cable

This is another variety of cable, also known as Coax. Coax has a conductor

surrounded by a Coaxial Cable insulating layer. The inner conductor is sometimes silver

plated to increase performance. This insulating layer is again surrounded by another

conducting layer around it.


56

______________________________________________________________________________________________

The whole tube like structure is

again insulated with another layer.

These kinds of cables are mostly used

to transmit radio frequency signals.

Coaxial cable frequency can

range from few megahertz to 18-20

Gigahertzes. As technology advances,

this range can increase even more.

They are best seen around for

transmitting cable television signals. Coax is just like any other electrical cable where

there are two conductors.

Nonmetallic-sheathed Cable

It cost less than other types of cables, is light in

weight and very simple to install, no special tools are

needed.

Armored Cable

Another common type of cable,

it is usually called by its trade name

BX, or other names such as flexsteel,

etc. the spiral armor is made of

galvanized steel.

Figure 7.6: Coaxial Cable

Figure 7.7: Nonmetallic-sheathed Cable

Figure 7.8: Armored Cable


57

______________________________________________________________________________________________

It has different sizes of cables according to their cross sectional area, it also

measure in AWG.

Table 7.3: Cable size: Metric cross-sectional area.


58

______________________________________________________________________________________________

EXERCISES 7.1

Direction: Identify the correct answer. Write the answer on the space provided.

________ 1. A material when the single filament or several filament woven or twisted

together.

________ 2. A wire which is consists of a single, solid round conductor.

________ 3. It measure the diameter of a wire in millimeters (mm) and inches (in), it

expressed as a whole number.

________ 4. What are the two classes of wires?

________ 5. A common type of cable that usually called by its trade name BX.

________ 6. A cord designated to carry electric currents or signals.

________ 7. The higher gauge numbers correspond with _______ diameter.

________ 8. A wire that has several non- insulated, thin round conductors, bundled or

woven together to form a single assembly.

________ 9. It classify when a cable are used as the connecting a cd player or tape

desk to amplifier.

________ 10. It classify when a cable are used as the extension cords, telephone

cords, and doorbell circuits.

59

POST TEST

I. Directions: Read the following questions then encircle the letter of the best

answer.

1. The same electrical charge ___________ each other.

A. repels B. attracts C. neutralize D. destroy

2. It is classified neither negatively nor positively charged particles.

A. electrostatic force

B. electron in motion

C. atom

D. neutron

3. The equal number of electron and proton in an atom.

A.negative B. positive C. neutral D. none of the above

4. It stated on Electron Theory that all matter is made up of _______________.

A. neutron B. atom C. molecules D. electron

5. The smallest particle of molecule.

A. proton B. ion C. atom D. electron

II. Read the following question then choose the letter of the correct answer in the

box below. Write your answers on the space provided.

_________ 6. What do you find at the center of an atom?

_________ 7. What is the attraction between the electron and the nucleus?

_________ 8. What do you call the negatively charged particle of an atom?

60

_________ 9. What do you call the positively charged particle of an atom?

_________ 10. What particle of an atom is not electrically charged?

III. Directions: Identify the following. Write the answer on the space below

11. Causes electrons to flow in a single direction along the wire.

_______________________________________________________

_

12. It is replaced Edison's DC battery system.

_______________________________________________________

_

13. Instead of applying the magnetism along the wire steadily, he

used a magnet that was rotating.

________________________________________________________

14. It is the flow or rate of flow of electric force in the conductor.

_______________________________________________________

_

15. Two classification of Electric Current

________________________________________________________

A-Electron B-proton C-neutron D-nucleus E-proton F-electrostatic force

61

IV. Directions: Tell whether the following idea refers to Alternating Current or Direct

Current. Write AC if the answer is Alternating Current and DC if it is Direct Current.

Write the answer on your paper.

16. Electrons keep switching directions - forward and backward.

________________________________________________________

17. The frequency is 50Hz or 60Hz depending upon the country.

________________________________________________________

18. Obtained from Cell or Battery.

________________________________________________________

19. Safe to transfer over longer city distances and can provide more power.

________________________________________________________

20. Electrons move steadily in one direction or 'forward'.

________________________________________________________

V. Direction: Find the missing quantity for each of the circuits below.

21. 5Ω I=2AV=?

62

________________________________________________________

22.

________________________________________________________

23.

________________________________________________________

24.

________________________________________________________

25.

________________________________________________________

I=2A

R=?

20V

I=?

10V

R=5Ω

R=?

1000V

I=500A

R=10Ω I=0.4AV=?

63

VI. Directions: Match Column A with Column B. Write the letter of the correct

answer on the space provided.

A B

____ 26. Switch A. current cannot pass through the bulb when the

other filament of the bulb is cut

____ 27. Source of

power

B. caused the load to light up

____ 28. Conductor C. consumes power

____ 29. Load D. electrical path

____ 30. Series

circuit

connection

E. bulb has its own circuit

F. control the circuit

VII. Directions: Identify the following. Write the answer on the space provided

________________ 31. It is the rate at which energy is used or the rate at

which work is done.

________________ 32. The measuring unit of electrical power is watt, named

after Scottish inventor and mechanical engineer.

________________ 33. It is one of the basic quantitative properties describing

a physical system or object's state.

64

VIII. Directions: Multiple Choices. Encircle the correct answer below.

34. Which of the following would normally be the best conductor?

A. copper

B. glass

C. steel

D. silver

35. Which of the following determines how good a material is as an electrical

conductor?

A. its superior strength in hot and cold weathers

B. the type of atoms that make up the material

C. the purity of the sample

D. when the electrons are free to flow

36. Substances that do not allow electricity to pass through them are:

A. conductors

B. cells

C. insulators

D. wires

37. What are those electrical conductors 8mm2 (AWG no. 8) and smaller sizes.

A. cables

B. wires

C. cord

D. cable wires

38. It is consist of group of wires twisted to form a metallic string.

65

A. stranded wires

B. solid wires

C. cable wires

D. cord

39. If a wire has a diameter of one mil, what is the cross sectional value of the

conductor.

A. One circular mil

B. One hundred circular mil

C. One thousand circular mil

B. One million circular mil

40. What do you call the larger conductors than the wires?

A. Wires

B. Cables

C. Cord

D. Conductors

66

ANSWER KEY

PRE TEST AND POST TEST

I.

1. A. Repel

2. C. Atom

3. C. Neutral

4. D. Electron

5. B. Atom

6. D. nucleus

7. F. electrostatic force

8. A. electron

9. B. proton

10. C. neutron

II.

11. Magnetic field

12. AC Generators

13. Nikola Tesla

14. Electric Current

15. Alternating Current and Direct Current

67

III.

16. AC

17. AC

18. DC

19. AC

20. DC

IV.

21. V=10

22. R=10

23. I=2

24. R=2

25. V

V.

26. F. Control the circuit

27. B. Caused the load to light up

28. D. Electrical path

29. C. Consumes power

30. A. Current cannot pass through the bulb when the other filament of the bulb is cut

VI.

31. Watt

32. James Watt

33. Energy

VII.

34. A. Copper

35. A. Its superior strength in hot and

cold weather

36. C. Insulators

37. B. Wires

38. Stranded Wires

39. A. One circular mil

40. B. Cables

68

69

UNIT I: INTRODUCTION TO ELECTRICITY

1. William Gilbert

2. Friction

3. Electron

4. Proton

5. Neutron

6. Geothermal Power

7. Molecular Theory

8. Electrostatic Force

9. Pressure

10. Elektron

UNIT II: COMPARISON OF AC TO DC

1. AC

2. DC

3. AC

4. DC

5. AC

6. AC

7. DC

8. AC

9. AC

10. DC

UNIT III: OHM’S LAW

1. 11 AMPS

2. 80 OHMS

3. 780V

4. 40.77….. OHMS

5. 234330 VOLTS

70

UNIT IV: ELECTRICAL CIRCUITS

I.

1. Series circuit

2. Parallel

3. Switch

4. Load

5. Conductors

II.

1. Source

2. Switch

3. Pathway or Conductor

4. Lamp

UNIT V: ELECTRICAL POWER AND ENERGY

I.

1. Electrical power

2. Energy

3. Watt

II.

1.Ampere

2. Power

III.

704 Watts

71

UNIT VI: CONDUCTORS AND INSULATOR

I.

1.Conductor.

2.Insulator

3.Polyvinylchloride

4.Silver, copper, and aluminum

5.Pin type insulator

6.Rubber

7.Electric shock

8.Suspension type

9.Strain insulator

10.Shackle insulators

II.

1.Conductor

2.Insulator

3.Conductor

4.Insulator

5.Conductor

6.Insulator

7.Insulator

8.Insulator

UNIT VII: WIRES AND CABLES

1. Wire

2. Solid wire

3. AWG American Wire Gauge

4. Solid and stranded

5. Armored cable

6. Cable

7. smaller

8. Stranded

9. Shielded

10.Unshielded

72

TECHNICAL TERMS USED IN THIS MODULE

UNIT I – INTRODUCTION TO ELECTRICITY

Atom is the smallest particle of molecule in which an element can be divided.

Electricity is a form of energy generated by friction, induction or chemical change.

Electron has a magnetic, chemical and radiant effect. It is also the negatively charged

particle of an atom.

Neutron is the particle of an atom which does not carry electrically charged.

Power is the rate at which heat is generated.

Proton is the positively charged particle of an atom.

Resistance is the opposition to the flow of current.

UNIT II – COMPARISON OF AC TO DC

Electrical Power is the time rate at which work is done or energy emitted or

transferred.

Hertz is a unit of frequency equal to one cycle per second.

Generator is a machine by which mechanical energy is changed into electrical energy.

Magnetic Field is the portion of space near a magnetic body or a current-carrying body

in which the magnetic forces due to the body or current can be detected.

Polarity is the particular state either positive or negative with reference to the two poles

or to electrification.

UNIT III – THE OHM’S LAW

Ampere is the standard unit used in measuring the strength of an electric current.

Ohms is the unit of electrical resistance.

Volt is the unit of measure for voltage.

UNIT IV – ELECTRIC CIRCUIT

Current is the flow or the rate of the flow of electric force in a conductor.

73

Parallel Circuit is an arrangement of electrical devices in a circuit in which the same

potential difference is applied to two or more resistances with each resistance being on

a different branch of a circuit.

Series Circuit is an arrangement of the parts of or elements in an electric circuit

whereby the whole current passes through each part or elements without branching.

Voltage is the electrical pressure that causes the electrons to move through a

conductor.

UNIT V –ELECTRICAL POWER AND ENERGY

Candle Power is the power comes from the combination of heat and light energy in a

load.

Horse Power is the power comes from a rotating object such as electric motors.

Kilowatt is equal to 1000 watts

Thermal Power is the power comes from a heating object like heater.

Watt is the absolute meter – kilogram – second unit of power equal to the work done at

the rate of one joule per second.

UNIT VI – CONDUCTORS AND INSULATORS

Conductor is a material that permits an electric current to flow easily

Insulator is a device made of an electrical insulating material and used for separating

or supporting conductors.

Polyvinyl chloride is a polymer of vinyl chloride used especially for electrical

installation, films and pipes.

UNIT VII – WIRES AND CABLES

Cable is an assembly of an electrical conductor insulated from each other but laid up

together.

Filament is a tenuous conductor made incandescent by the passage of an electric

current. It is also a cathode in the form of a metal wire in an electron tube.

Wire is an electric conductor insulated separately.

74

REFERENCES

BOOKS

Agpaoa, Feleciano. Interior and Exterior Wiring Troubleshooting. National Bookstore:

1991.

Cardenas, Elpidio J. Fundamental and Elements of Electricity.

Gibilisco, Stan; Electricity Demystified: A Self Teaching Guide, New York, McGraw-Hill,

2005

Fajardo, Max B. and Fajardo, Leo R. Electrical Layouts and Estimates.2nd Edition; 5138

Trading, 2000

Middleton, Robert Gordon and Rosenberg, Paul; Audel Practical Electricity: All New 5 th

Edition, John Wiley & Sons, 2004

National Electrical Code (NEC)

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77

ABOUT THE RESEARCHERS

Jerwin V. Lopez is an Electrical Technology student

taking Bachelor of Technical Education at Marikina

Polytechnic College. His strongest suit is his study for the

field for four years started when he was in high school.

His specialty is building wiring installation. He has a

Certificate of Competency given by TESDA because of

taking NCII for Electrical Installation and Maintenance.

Aside from aspiring to become a professor in Electrical Technology, Mr. Lopez is also

aspiring to become a Master Electrician.

Gio P. San Buenaventura is an Electrical Technology

student taking Bachelor of Technical Teacher Education

at the same school. His strongest suit is passing at

Electrical Installation and Maintenance NCII since 2012.

His specialty is electrical motor.

Genelan C. Francisco is an Electrical Technology student

taking Bachelor of Technical Teacher Education at the

same school. His specialty is logic circuit and theories

about electricity. He was first started taking electricity when

he was in high school.

Donna Femie C.

Calimbayan is an Electrical Technology student taking

Bachelor of Technical Teacher Education at the same

school. Although she was the only girl on her batch, she

was competent in electrical technology. Her specialty is

on theories about electricity.

78

ABOUT THE MODULE REVIEWERS

Mr. Ramil A. Caballero is a professor in electrical

technology at Marikina Polytechnic College. He take

Master of Arts and he was almost a years of teaching

at the said school. He became a judge and facilitators

of Skills Olympics and resource teacher of field study 4,

5, 6. His strongest suit is his passing of TESDA

Building Wiring Installation NC II, National TVET

Trainers Level I and National TVET Assessor Level I

passer.