Al-Dhaifallah_Term332 1EE2010_Lecture2

2. Introduction

Dr. Mujahed Al-Dhaifallah

EE2010: Fundamentals of Electric Circuits

Term 332

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Dr. Mujahed Al-Dhaifallahالله. ضيف آل مجاهد د

Office: Dean Office. E-mail: muja2007hed@gmail.com Telephone: 7842983 Office Hours: SMT, 1:30 – 2:30 PM,

or by appointment

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Rules and Regulations

· No make up quizzes · DN grade == 25% unexcused absences· Homework Assignments are due to the

beginning of the lectures. · Absence is not an excuse for not

submitting the Homework.

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Grading Policy

Exam 1 (10%), Exam 2 (15%) Final Exam (60%), Quizzes (5%) HWs (5%) Attendance & class participation (5%), penalty for late

attendance Note: No absence, late homework submission

allowed without genuine excuse.

EE2010_Lecture2

Attendance

Regular lecture attendance is required. There will be part of the grade on attendance

If you missed any class or tutorial, you are still responsible for anything you miss—announcements, quizzes, etc.

Quizzes

AnnouncedAfter each HW. From HW material

Assignment Requirements

Late assignments will not be accepted.assignments are due at the beginning of

lecture. Sloppy or disorganized work will

adversely affect your grade.

Exams

Attendance is mandatory.Make-up exam are not given unless

a valid, documented emergency has arisen

Homework

Send me e-mailSubject Line: “EE 2010 Student”

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The Course Goal

The aim of this course is to provide an understanding of the fundamentals and analysis of electric circuits.

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Course Objectives

After successfully completing the course, the students will be able to

1. Understand the fundamental concepts of electric circuits.

2. Understand the main circuit elements including energy storage elements.

3. Learn the different circuit analysis techniques.

4. Obtain the equivalent circuits and find out the conditions of maximum power transfer.

5. Apply analysis techniques to sinusoidal circuits.

6. Evaluate the power in sinusoidal circuits.

Textbooks

Introductory Circuit AnalysisRobert Boylestad

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Course Syllabus

1. Introductory material: Introduction2. Basic circuit elements and concepts:

Current, Voltage, Resistance. Chapters (2 and 3)

3. Basic laws of circuit theory: Ohm's law, Power and Energy. Devices: Battery, Power Supply, Multi-meters, Circuit Breakers (Chapter 4)

4. Series Circuits, Kirchhoff's Voltage law. (Chapter 5)

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Course Outlines

4. Parallel Circuits, Kirchhoff's Current law (Chapter 6)

5. Series - Parallel Circuits. (Chapter 7)

6. Techniques of circuit analysis: Source transformation, nodal and mesh analysis. (Chapter 8)

7. Circuit theorems: superposition principle, Thevenin and Norton theorems; maximum power transfer theorem. (Chapter 9)

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Course Outlines

6. Capacitors, Inductors, Series and Parallel connection. (Chapters 10 and 12)

7. Sinusoidal Source, Complex Numbers, Frequency Domain (Phasor) Circuit. (Chapters 13 and 14).

Current, Voltage and Resistance

EE 2010: Fundamentals of Electric CircuitsMujahed AlDhaifallah

Atoms and their structure

electron

neutron

proton

Atomic Structure

Mass of an Electron = 9.11 x 10-28 gm.Mass of a Proton = 1.672 x 10-24 gm.Proton is ~1836 times heavier than the

electron

Atomic Structure

Unit of Charge = CoulombsCharge on electron = charge on a proton

= 1.6 x 10-19 C1 Coulomb = Charge on 6.242 x 1018

electrons

Coulomb’s Law

Like charges repel, opposites attractF = k Q1 Q2 / r2

k = 9 x 109 (units?)

Coulomb’s Law

Like charges repel, opposites attractF = k Q1 Q2 / r2

K = 9 x 109 N m2/C2

Conduction

In metals, the electrons are “more free” than the insulators.

Whenever there is a charge present at one end, the electrons flow to (or away) from that charge.

Current

Rate of flow of charge1 Amp = 1 Coulomb / 1 Second.

Question

If a laptop constantly needs 2 Amps current from a battery, how many electrons are drained from the battery in one hour?

1 Amp = 6.242 x 1018 electrons/second 2 Amp = 12.484 x 1018 electrons/second In one hour - > 3600 x 12.484 x 1018 electrons Answer is 4.49 x 1022 electrons

Question

What’s the weight of all those electrons?4.49 x 1022 x 9.11 x 10-28 gm4.09 x 10-5 gm

Equations

I = Q/ tQ = I x tt = Q/I

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Examples

Find the current in amperes if 650 C of charge pass through a wire in 50 s.

If 465 C of charge pass through a wire in 2.5 min, find the current in amperes.

If a current of 40 A exists for 1 min, how many coulombs of charge have passed through the wire?

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Example

Consider the plot of net positive charge moving past a point shown in Fig. Over the time interval 1 s ≤ t ≤ 3 s. Find i(t)

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Potential

Every particle of mass m raised to a height h above the earth’s surface has a potential energy m.g.h

This potential energy can be raised by raising the particle a little higher

When the particle is set free, it travels to the point of least potential.

Electric Potential

Similarly, a charge wants to travel to a lower “electric” potential.

A negative charge on the other hand, wants to travel to a higher potential.

Each point in a circuit has a potential.

Voltage

Voltage is always measured between two points.

It is defined as the difference of potential between the two points.

Measured in volts

Volts

1 volt is defined as the potential difference, which results in an energy exchange of 1 Joule due to the movement of 1 Coulomb across it.

DC Voltage Supply

Conductivity

Copper is the most popular conductor.

Metal Conductivity (%)

Silver 105

Copper 100

Gold 70.5

Aluminum 61

Tungsten 31.2

Nickel 22.1

Iron 14

Constantan 3.52

Nichrome 1.73

Calorite 1.44

Resistance

Resistance is proportional to length

length

direction of current flow

Resistance

Resistance is inversely proportional to the cross sectional area

direction of current flow

Resistance

R = ρ L/A ρ is the resistivity of

the material (units?)

Material ρ (10-8 Ohm-Metres)

Silver 1.645

Copper 1.723

Gold 2.443

Aluminum 2.825

Tungsten 5.485

Nickel 7.811

Iron 12.299

Tantalum 15.54

Nichrome 99.72

Tin Oxide 250

Carbon 3500

Color Coding

5 Bands of code (3 are mandatory)Bands 1 - 3 the value of the resistorBand 4 the range (tolerance)Band 5 the reliability

Color Code (Band 1-3)

Color Value

Black 0

Brown 1

Red 2

Orange 3

Yellow 4

Green 5

Blue 6

Violet 7

Gray 8

White 9

Example

2 6 x 103 = 26 K Ohms

Band 3 (special cases)

Gold = 0.1Red Blue Gold = 2.6 Ohm

Silver = 0.01Red Blue Silver = 0.26 Ohm

More Bands

Band 4 Tolerance

Gold 5%

Silver 10%

None 20%

Band 5 Reliability (after 1000 Hrs of use)

Brown 1%

Red 0.1%

Orange 0.01%

Yellow 0.001%

Example

= 26 K Ohms ± 5%, 1 in 100,000 fails after 1000 hrs of use