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Fundamental of Electrical circuits

Learn electrical units and definitions, circuit elements, Kirchhoff’s Laws, sinusoidal analysis, superposition theorem, and more. Dive into circuit theory and analysis using the textbook "Engineering Circuit Analysis". Enhance your problem-solving skills, design abilities, and computer-aided analysis expertise. Master basic components, electric circuits, and fundamental concepts in electrical engineering.

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Fundamental of Electrical circuits

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  1. Fundamental of Electrical circuits

  2. Course Description: Electricalunitsanddefinitions:Voltage,current, power,energy,circuitelements: resistors, capacitors, inductors,independentanddependentsources. CircuitTheory and analysismethods: Kirchhoff’sLaws,voltageandcurrent divider,nodeandmeshanalysis,TheveninandNorton theorem,maximumpowertransfer,superposition theorem. SinusoidalSteady StateAnalysis:sinusoidproperties, complexnumber representations,phasors, circuit theory andanalysis methodinAC circuits.

  3. Textbook: WilliamH.Hayt,Jr.,JackE.Kemmerly,Steven M.Durbin“EngineeringCircuitAnalysis”, Eighth edition,McGraw-Hill.

  4. Chapter 1: Introduction Circuittheory: Afieldasdiverseas electricalengineering Electriccircuits:commonfor EE.: Amathematicalmodel,whichapproximates thebehaviorofanactualelectric system

  5. Overview: • Linearcircuitanalysis: • Resistivecircuitanalysis:introduceanumber ofvery powerfultechniques,suchasnodal analysis,meshanalysis,superposition,etc. • time-domainanalysis:allowcapacitors and inductorsto beincludedinacircuit. • frequency-domainanalysis:transform differentialequationsintomoreeasilymanaged algebraicequations.

  6. Relationship: RelationshipofCircuitAnalysistoEngineering: Learninghowtoanalyzeaproblem. Tolearnhowto •Tobemethodical •Todeterminethegoalofaparticularproblem •Towork withtheinformationgivento develop aplanofattack •Toimplementtheplantoobtainasolution •Toverify thattheproposedsolutionisaccurate

  7. AnalysisandDesign: This textisfocusedondevelopingour abilitytoanalyzeandsolveproblem. Developingourdesignskillscomesless naturallyto usthandevelopingouranalytical skills.

  8. Computer-Aided Analysis: Moderncircuitanalysissoftwareis rapidly increasinginitslevelofintegration. Weneedtohaveasolidunderstandingof howcircuits workinorderto developanability todesignthem.

  9. Problem-Solving: Asuggested problem- solvingflowchart

  10. Problem-Solving: • Developtheskillstosuccessfullyattackthe • unsolvedproblems • Identifywhat’s givenandwhat’s to befound • Sketcha circuitdiagramorothervisualmodel • label,reference,redrawtosimpleform • simplified • Thinkofseveralsolutionmethods andaway of choosingamongthem • Calculateasolution • paperandpencil • calculator • Useyourcreativity • Test yoursolution

  11. Chapter 2: BasicComponentsandElectricCircuits

  12. Objectives: • Definitionofbasicelectricalquantitiesandassociatedunits • Therelationshipbetweencharge, current, voltage,andpower • Thepassivesignconvention • Dependentand independentvoltageand currentsources • ThebehavioroftheresistorandOhm’slaw

  13. Unitsand Scales: • In order to state the value of some measurable quantity, we must • give both a number and a unit, such as “3 meters. • The most frequently used system of units is the International • System of Units (abbreviated SI in all languages). TABLE :2.1 SI BaseUnits The fundamental unit of work or energy is the joule (J). One joule = in SI base units) The fundamental unit of power is the watt (W), defined as 1 J/s.

  14. Unitsand Scales: TABLE2.2 SI Prefixes

  15. Charge: • There are two types of charge: • positive (corresponding to a proton) and • negative (corresponding to an electron). • the fundamental unit of charge is the coulomb (C). • It is defined in terms of the ampere by counting the total charge that • passes through an arbitrary cross section of a wire during an interval of • one second; one coulomb is measured each second for a wire carrying • a current of 1 ampere (Fig. 2.1). • In this system of units, a single electron has a charge of • and a single proton has a charge of • A quantity of charge that does not change with time • is typically represented by Q. • The instantaneous amount of charge • (which may or may not be time-invariant) • is commonly represented by q(t), or simply q.

  16. Current: • Electrical current is the time rate of flow of electrical charges through a • conductor or circuit element. • Current is symbolized by Ior i, and so • The unit of current is the ampere (A), It is commonly abbreviated as an • “amp,”. • One ampere equals 1 coulomb per second. (A=C/s). • The charge transferred between time tₒand t • may be expressed as a definite integral: • The total charge transferred • over all time is thus given by

  17. Current:

  18. Current: Twodifferentmethodsoflabelingthesamecurrent. (a,b)Incomplete,improper,and incorrectdefinitionsofacurrent. (c)thecorrectdefinitionofi1(t).

  19. Current:

  20. Voltage: • An electrical voltage (or a potential difference) exists between two • terminals is a measure of the work required to move charge • through the element. • The unit of voltage is the volt (V), and 1 volt is the same as 1 J/C. • Voltage is represented by V or v. • A voltage can exist between a pair of electrical terminals whether a • current is flowing or not. • Voltages are assigned polarities that indicates the direction of • energy flow. • The voltage is indicated by a plus-minus pair of algebraic signs.

  21. Voltage: (a,b) Theseareinadequatedefinitionsof avoltage.(c)Acorrectdefinitionincludes bothasymbolforthevariableand aplus- minussymbolpair. (a,b) TerminalBis5Vpositivewith respecttoterminalA; (c,d) terminalAis5Vpositivewith respecttoterminalB.

  22. Power: • It is represented by P or p. • Its unit is watts (W) • Passive sign convention • If a positive current is entering a positive terminal of • an element, then the energy is supplied to the element • (or the element absorbs the power). • If a positive current is entering a negative terminal of • an element, then the energy is supplied by the element • (or the element generates the power).

  23. Power: Computethe powerabsorbedbyeachpart.

  24. Power: Computethe powerdelivered byeachpart.

  25. Energy calculation:

  26. Sources: Symbolforanindependentcurrent source. Symbolforindependent voltage source:(a)DCvoltagesource; (b)battery;(c)acvoltagesource. Thefourdifferenttypes ofdependentsources: current-controlled currentsource; (CCC) voltage-controlled currentsource; (VCC) voltage-controlledvoltagesource; (VCV) current-controlledvoltagesource. (CCV)

  27. Dependant sources

  28. Example: Inthecircuitbelow,ifv2 isknowntobe 3V,findvL.

  29. Example: Findthepowerofeachelementinthecircuitbelow.

  30. Networkand Circuits: Theinterconnectionoftwoormore simplecircuitelementsformsandelectricalnetwork.Ifthenetworkcontainsatleastone closedpath,itis alsoanelectriccircuit.

  31. Ohm’sLaw: Ohm’s law states that the voltage across conducting materials is directly proportional to the current flowing through the material • where the constant of proportionality R is called the resistance. The unit of • resistance is the ohm, which is 1 V/A and customarily abbreviated by a • capital omega, Ω.

  32. Ohm’sLaw: passiveelement:R,L,C activeelement: sources

  33. Example:

  34. Homework: Determinethe powerbeingabsorbedbyeach ofthecircuitelementsshown

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