part 1 basicconcepts

7/28/2019 Part 1 BasicConcepts

1/43

1

ELE211Electric Circuit I

Chapter 1

Basic Concepts

Slides based on textbook by Alexander


2/43

2

Instructor: Maher Bakri-KassemOffice No. EB2 - 219

Phone No. 515-2932

E-mail: [email protected]


3/43

3

Course References

Primary:C. K. Alxander and M. N. Sadiku,Fundamentals of Electric Circuits, 4thEdition, McGraw-Hill, 2009.

Supplementary:Course notes (iLearn)

Irwin, J. D., Basic Engineering CircuitAnalysis, 7th edition, 2002, John Wiley &Sons.

Software: MATLAB and PSPICE


4/43

4

Marking Scheme

Homework & Quizzes 10%

Laboratory 20%

Two Midterm Exams 40%

Final 30%

Total 100%


5/43

Attendance:Will be taking at the beginning of each

class

University policy of attendance will beapplied.

Once the class is in progress, studentsmust stay until the class is over.

Students who are late more than 5minutes will not be allowed to join theclass.

Mobile phones are to remain switchedoff as long as class is in session.

5


6/43

Home work:4-5 assignments

Maximum of 1 week will be given for eachhomework.

No late homework will be accepted.

A cover page is required for eachassignment. The cover page should

include course title, section number,student name and ID, and homeworknumber.

Students are encouraged to discusshomework problems in small groups, butcopied work will not be accepted anda grade of zero will be assigned to allstudents involved. 6


7/43

Quizzes 4-5 quizzes will be given.

The quiz will be from the homeworkmaterial (not necessary the samequestions).

The quizzes will be 1-2 days afterhomework submission date.

7


8/43

Midterms (tentative)Exam #1, TPD.

Exam #2, TPD.

Office Hours:UMTW (1:30 - 2:30),

or by appointment

8


9/43

9

Course OutlineTopic Number of weeks

Circuit Variables: voltage, current, energy, and power 1

Ohms law 1

Kirchoffs laws, sources, resistance 1

Resistive networks: voltage divider and current

divider

1

Nodal analysis 1

Mesh analysis 1Superposition, Thevenin and Norton equivalent

circuits

2

Capacitors and inductors: stored energy, terminal

relations

1

Natural and forced response of RL and RC circuits 2

Sinusoidal steady state: complex phasors, impedance 1

Average, reactive and complex power, effective value 1

Maximum power transfer 1

Review and evaluation 1


10/43

10

Labs and RecitationsWeek Experiment

1 Lab Introduction; familiarization with lab

equipments1 Ohms law and Kirchoffs Laws

2 DC Circuit Analysis in PSpice

2 Thevenins theorem and maximum power

transfer (practical & PSpice)3 IntroductiontoMatlab3 Familiarization with Oscilloscope and

Function Generator4 Transient Response of RL and RC Circuits

4 Transient Analysis in PSpice

5 Steady State Response of AC circuits

5 ACAnalysisinPSpice6

LabFinalExam


11/43

CIRCUITS I

DEVELOP TOOLS FOR THE ANALYSIS AND DESIGN OFBASIC LINEAR ELECTRIC CIRCUITS

11


12/43

a b

2 TERMINALS COMPONENT

characterized by the

current through it andthe voltage differencebetweeb terminals

NODE

NODE

Electric circuit is an interconnection of electrical components

+

-

L

C

1R

2R

Sv

Ov

TYPICAL LINEARCIRCUIT

12


13/43

BASIC CONCEPTS

System of Units: The SI standard system; prefixes

Basic Quantities: Charge, current, voltage, power and energy

Circuit Elements: Active and Passive

13


14/43

14


15/43

Informationat thefoundationofmodernscience andtechnology

fromthe PhysicsLaboratoryofNIST

Detailedcontents

ValuesoftheconstantsandrelatedinformationSearchablebibliographyontheconstants

In-depthinformationontheSI,themodernmetricsystem

Guidelinesfortheexpressionofuncertaintyinmeasurement

About thisreference. Feedback.

PrivacyStatement/SecurityNotice - NIST Disclaimer

15


16/43

Basic Quantities

Electrical current:-Flow of electrons through a wire or otherelectrical conductor

- Electrons are negatively charged particles

- The time rate of flow of electrical chargethrough a conductor or circuit element

- The units are amperes (A), which areequivalent to coulombs per second (C/s)

- The charge per electron is -1.60210-19 C

16


17/43

)(tq

- If the charge is given determine the current byDifferentiation- If the current is known determine the charge by

Integration

A physical analogy that helps visualize electricCurrents is that of water flow.Charges are visualized as water particles

17


18/43

)(tq

Example 1:

])[120sin(104)( 3 Cttq

)(ti )120cos(120104 3 t ][A

][)120cos(480.0)( mAtti

Example 2:

0

00

)( 2 tmAe

t

ti t

Find the charge that passesDuring in the interval 0


19/43

1 2 3 4 5 610

102030

Charge(pC)

ime(ms)

Here we are given theCharge flow as

function Of time.

)/(10100102

10101010 93

1212

sCs

Cm

1 2 3 4 5 610

10

20

30

ime(ms)

)Current(nA40

20

Example 3:Determine thecurrent

To determinecurrent we musttake derivatives.PAY ATTENTION TO

UNITS

19


20/43

Convention for currents

It is absolutely necessary to indicate

The direction of movement of chargedParticles.

The universally accepted convention inElectrical engineering is that current isFlow of positive charges.

And we indicate the direction of flowFor positive charges

-the reference direction-

A positive value forThe current indicates

Flow in the directionOf the arrow (theReference direction)

A negative value forThe current indicatesFlow in the oppositeDirection than theReference direction

a b

a

a

ab

b

b

A3

A3 A3

A3

The double index notation

If the initial and terminal node areLabeled one can indicate them asSubindices for the current name

a bA5AIab 5

AIab

3

AIba 3

AIab

3

AIba 3

Positive chargesFlow left-right

Positive chargesFlow right-left

baab II 20


21/43

Voltage:

- The force that pushes electricity through a wire

- The voltage associated with a circuit elementis the energy transferred per unit of chargethat flows through the element. The units ofvoltage are volts (V), which are equivalent to

joules per coulomb (J/C)

21


22/43

Conventions for voltages

Two points have a voltage differential of one volt if onecoulomb of charge gains (or loses) one joule of energywhen it moves from one point to the other

a

b

C1

- If the charge gains energy moving froma to b then b has higher voltage than a.

- if it loses energy then b has lower voltagethan a

Voltage is always measured in a relative form as the voltage differencebetween two points

It is essential that our notation allows us to determine which pointhas the higher voltage

22


23/43

The + and - signsdefine the reference

polarity

V If the number V is positive point A has Vvolts more than point B.If the number V is negative point A has|V| less than point B.

Point A has 2V more

Than point B

Point A has 5V lessThan point B

23


24/43

The two-index notation for voltages

VV B 2

VVAB 5 VVBA 5BAAB VV 24


25/43

25


26/43

26


27/43

A consequence of this convention is that the reference directions for

current and voltage are not independent 27


28/43

28


29/43

29


30/43

This battery supplies energy This battery receives the energ

30


31/43

DETERMINE WHETHER THE ELEMENTS ARE SUPPLYING OR RECEIVING POWERAND HOW MUCH

a

b

a

b

WHEN IN DOUBT LABEL THE TERMINALSOF THE COMPONENT

AIab 4

VVab 2

WP 8 SUPPLIES POWER

VVab 2

A2

AIab 2

WP 4 RECEIVES POWER

1

2

1

2

AIVV 4,12 1212 AIVV 2,4 1212 31


32/43

Select voltage reference polaritybased on current reference direction

)5(][20 AVW AB

][4 VVAB

IVW )5(][40

][8 AI

Select here the current reference directionbased on voltage reference polarity

A2

)2(][40 1 AVW

][201 VV

IVW ])[10(][50

][5 AI

32


33/43

+

-

V24

V6

V18

A2

A2

1

23

P1 = 12WP2 = 36W

P3 = -48W

)2)(6(1 AVP

)2)(18(2 AVP

)2)(24()2)(24(3 AVAVP

IMPORTANT: NOTICE THE POWER BALANCE IN THE CIRCUIT

COMPUTE POWER ABDORBED OR SUPPLIED BY EACH ELEMENT

33

CIRCUIT ELEMENTS


34/43

CIRCUIT ELEMENTS

VOLTAGEDEPENDENTSOURCES

CURRENT

DEPENDENTSOURCES

PASSIVE ELEMENTS

Absorb energy (may store)

INDEPENDENT SOURCES

Supply energy34


35/43

35


36/43


37/43

37


38/43

38


39/43

39

EXERCISES WITH DEPENDENT SOURCES


40/43

EXERCISES WITH DEPENDENT SOURCES

OVFIND ][40 VVO OIFIND mAIO 50

DETERMINE THE POWER SUPPLIED BY THE DEPENDENT SOURCES

][40 V

][80])[2])([40( WAVP

TAKE VOLTAGE POLARITY REFERENCE TAKE CURRENT REFERENCE DIRECTION

][160])[44])([10( WAV

40

POWER ABSORBED OR SUPPLIED BY EACH USE POWER BALANCE TO COMPUTE Io


41/43

ELEMENT

][48)4)(12(1 WAVP ][48)2)(24(2 WAVP

][56)2)(28(3 WAVP

][8)2)(4()2)(1( WAVAIP xDS

][144)4)(36(36 WAVP V

NOTICE THE POWER BALANCE

W12

))(6( OI)9)(12(

)3)(10(

)8)(4( )11)(28(

POWER BALANCE

][1 AIO 41


42/43

42

Measuring Voltage and


43/43

Measuring Voltage and

Current

43

part 1 basicconcepts

Documents