Learn Basic Circuit

8/8/2019 Learn Basic Circuit

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EE111EE111

Circuit AnalysisCircuit Analysis

Slides prepared by a studentBy getting a material from net

Introduction


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Lecture OutlineLecture Outline

yWhat do Electrical Engineers Do?

y Charge

y

Currenty Electrical Energy

y Electrical Power

y

Circuit Elementsy Dependent Vs Independent Sources

2Introduction


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What do Electrical Engineers Do?What do Electrical Engineers Do?

y Electrical Engineers design, construct,

analyze and improve electrical and

electronic components and systems in

all shapes and sizes.

3Introduction


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Electrical Engineering OverviewElectrical Engineering Overview

y Communication System

y Computer System

y

Control Systemy Power System

y Signal Processing System

4Introduction


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5Introduction


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6Introduction


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7Introduction


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8Introduction


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9Introduction


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Circuit Analysis Course Covers Circuit Analysis Course Covers

11Introduction


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Basic Circuit ElementsBasic Circuit Elements

12Introduction


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Relation describing behavior ofRelation describing behavior of

circuit componentscircuit components

13Introduction


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Problem SolvingProblem Solving

y Identify what is given and what to find

y Sketch a circuit diagram or visual model

y Think of several solution methods and

decide on a way of choosing among

them

y Calculate a solution

y Use your creativity

14Introduction


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International System of UnitsInternational System of Units

15Introduction


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Derived Units in SIDerived Units in SI

Quantity Unit Name Formula

Frequency Hertz (Hz) s-1

Force newton (N) Kg*m/s2

Energy or work joule (J) M.MPower watt (W) J/s

Electric Charge coulomb (C) A.S

Electric Potential volt (V) J/C

Electrical Resistance ohm () V/A

Electrical Conductance siemens (S) A/V

Electric Capacitance farad (F) C/V

Inductance henry (H) V*s/A

16Introduction


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SIPrefixesSIPrefixes

17Introduction


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Charge (1)Charge (1)

y Charge is an electrical property of theatomic particles of whichmatter consists,measured in coulombs (C).

y

The charge e on an electron is negative andequal in magnitude to 1.6021019 C, whilea proton carries a positive charge of thesame magnitude as the electron.

y

The presence of equal numbers of protonsand electrons leaves an atom neutrallycharged.

18Introduction


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Charge (2)Charge (2)

The following points should be noted about electric charge:

y The coulomb is a large unit for charges. In 1 C of charge,there are 1/(1.602 1019) = 6.24 1018 electrons. Thusrealistic or laboratory values of charges are on the orderof pC, nC, orC

y According to experimental observations, the only chargesthat occur in nature are integral multiples of theelectronic charge e = 1.602 1019 C.

y

Th

e law of conservation of charge states that charge canneitherbe created nor destroyed, only transferred. Thusthe algebraic sum of the electric charges in a system doesnot change.

19Introduction


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Electric CurrentElectric Current

y Electric current is the time rate of change

of charge, measured in amperes (A).

20Introduction


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Direct Current Vs AlternatingDirect Current Vs Alternating

CurrentCurrenty A direct current (dc) is a current that remains

constant with time.

y An alternating current (ac) is a current thatvaries sinusoidally with time.

21Introduction


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Examples (1)Examples (1)

22Introduction


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23Introduction


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24Introduction


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25Introduction


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Voltage (1)Voltage (1)

26Introduction


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y Voltage is the energy absorbed or expended as a unitcharge moves through a circuit element

y Analogous to pressure in hydraulic systemy Sometimes called potential differencey Can be created by a separation of chargey Is a measure of the potential between two pointsy Voltage pushes charge in one directiony We use polarity (+ and on batteries) to indicates

which direction the charge is being pushedy Voltage is the energy required to move a unit

charge through an element, measured in volts (V)

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where v= voltage in volts

w = energy in Joules

q = charge in coulombs

Introduction


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28Introduction


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29Introduction


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y The voltage sources push current through the circuit

y The current is the rate flow of charge (i.e. electrons)

y The light bulb (resistor) resists the flow of current

Introduction


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Power (1)Power (1)

31Introduction


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Power (2)Power (2)

32Introduction


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Power (3)Power (3)

33Introduction


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Energy (1)Energy (1)

34Introduction


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Example 1 (1)Example 1 (1)

35Introduction


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36Introduction


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37Introduction


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Example 2Example 2

38Introduction


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1.6 Circuit Elements1.6 Circuit Elements

Introduction


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Kinds of SourcesKinds of Sources

Introduction


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41Introduction


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42Introduction


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43Introduction


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Notes on Ideal SourcesNotes on Ideal Sources

y Ideal sources are models used to simplify analysis

y These devices do not exist physically

y Ideal models serve as a good approximation of physical devices, butonly over a limited operating range

y We will use and discuss more accurate models later in the term

Introduction


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