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Electrical Engineering: Principles and Applications, 6eAllan R. Hambley

Copyright 2014 by Pearson Education, Inc.All rights reserved.

EE292CHAPTER 1 INTRODUCTION

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EE292

Table 1.1 Current andEmerging Electronic/ElectricalApplications in Automobiles andTrucks

Automobile Electronics (I)

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Table 1.1 (continued)Current and EmergingElectronic/Electrical Applicationsin Automobiles and Trucks

Automobile Electronics (II)

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Figure 1.2 The headlight circuit. (a) The actual physicallayout of the circuit. (b) The circuit diagram.

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EE292 Review of Atom Structure,

Coulomb Force, & Electrical Field

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EE292 Potential, Difference, and Voltage,

Voltage is the difference in electric potential energyof a

unit chargetransported between two points
http://en.wikipedia.org/wiki/Electric_potential_energyhttp://en.wikipedia.org/wiki/Electric_chargehttp://en.wikipedia.org/wiki/Electric_chargehttp://en.wikipedia.org/wiki/Electric_potential_energy

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Lighting is dueto high voltage

discharge: large

electrical

currents, andelectron

Electrical Charges, Currents In Nature

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EE292Figure 1.4 Current is the time rate of charge flowthrough a cross section of a conductor or circuit element.

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Figure 1.14 When current flows through an element andvoltage appears across the element, energy is transferred. Therate of energy transfer is p= vi.

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Figure 1.3 An electrical circuit consists of circuit elements,such as voltage sources, resistances, inductances, andcapacitances, connected in closed paths by conductors.

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Figure 1.5 Plots of charge and current versus time forExample 1.1. Note: The time scale is in milliseconds(ms). One millisecond is equivalent to 103seconds.

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EE292Figure 1.6 In analyzing circuits, we frequently start byassigning current variables i1, i2, i3, and so forth.

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EE292 Figure 1.7 Examples of dc and ac currents versus time.

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EE292AC currents can have various waveforms.

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Figure 1.9 Reference directions can be indicated by labelingthe ends of circuit elements and using double subscripts oncurrent variables. The reference direction for iabpoints from ato b. On the other hand, the reference direction for ibapointsfrom bto a.

Figure 1.13 The positive referencefor is at the head of the arrow.

Fi 1 11 If d k h l l d

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Figure 1.11 If we do not know the voltage values andpolarities in a circuit, we can start by assigning voltagevariables choosing the reference polarities arbitrarily. (Theboxes represent unspecified circuit elements.)

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Figure 1.14 When current flows through an element andvoltage appears across the element, energy is transferred. Therate of energy transfer is p= vi.

p= vi.

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EE292 Figure 1.16 Circuit element for Example 1.3.

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Table 1.2 Prefixes Used forLarge or Small Physical Quantities

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EE292 Figure 1.17 See Exercise 1.6.

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EE292

KCL: Kirchhoff Current Law(Kirchhoffs first law, first rule, node rule)

The net current entering into a node is zero

=1 =0

=1 =0

Complex

numbers

Real

numbers

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EE292

KCL: Kirchhoff Current Law(Kirchhoffs first law, first rule, node rule)

The net current entering into a node is zero

=1 =0

=1 =0

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EE292Figure 1.18 Partial circuits showing one node each toillustrate Kirchhoffs current law.

1 2+3=0 3+4=0 567=0

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Figure 1.19 ElementsA, B, C, and Dcan be considered to beconnected to a common node, because all points in a circuitthat are connected directly by conductors are electricallyequivalent to a single point.

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EE292 Figure 1.20 ElementsA, B, and Care connected in series.

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EE292 Figure 1.21 See Exercise 1.7.

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EE292 Figure 1.22 Circuit for Exercise 1.8.

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EE292 KVL: Kirchhoff Voltage Law(Kirchhoffs second law, second rule, loop rule)

The algebraic sum of the voltages equals zero

for any closed path (loop) in an electric circuit

=1 =0

=1 =0 Complex

numbers

Real

numbers

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Figure 1.23 In applying KVL to a loop, voltages are added orsubtracted depending on their reference polarities relative tothe direction of travel around the loop.

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EE292Figure 1.24 Circuit used for illustration of Kirchhoffs voltagelaw.

+ +=0 +

=0

+ + =0

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Figure 1.25 In this circuit, conservation of energy requires

thatvb= va+ vc.

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EE292Figure 1.26 In this circuit, elementsAand Bare in parallel.Elements D, E, and Fform another parallel combination.

Fi 1 27 F thi i it h th t Th

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Figure 1.27 For this circuit, we can show that va=vb=vc. Thus,

the magnitudes and actual polarities of all three voltages arethe same.

Fi 1 28 A l i i i lifi d b i th lt

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Figure 1.28 Analysis is simplified by using the same voltagevariable and reference polarity for elements that are inparallel.

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EE292 Figure 1.29 Circuit for Exercises 1.9 and 1.10.

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EE292 Figure 1.30 Independent voltage sources.

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EE292Figure 1.31 We avoid self-contradictory circuit diagramssuch as this one.

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Figure 1.32 Dependent voltage sources (also known ascontrolled voltage sources) are represented by diamond-shaped symbols. The voltage across a controlled voltagesource depends on a current or voltage that appears elsewherein the circuit.

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EE292 Figure 1.33 Independent current sources.

Figure 1 34 Dependent current sources The current through

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Figure 1.34 Dependent current sources. The current througha dependent current source depends on a current or voltagethat appears elsewhere in the circuit.

Figure 1 35 Voltage is proportional to current in an ideal

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Figure 1.35 Voltage is proportional to current in an idealresistor. Notice that the references for vand iconform to thepassive reference configuration.

=

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EE292Figure 1.36 If the references for vand i are opposite to thepassive configuration, we have v=Ri.

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EE292Figure 1.37 We construct resistors by attaching terminals toa piece of conductive material.

Figure 1 38 Resistors often take the form of a long cylinder

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Figure 1.38 Resistors often take the form of a long cylinder(or bar) in which current enters one end and flows along thelength.

=

= Resistivity, L=Length, A=Area

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Table 1.3 Resistivity Values

(m) for Selected Materials at300 K

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EE292 Electric Power

Power = Total Energy / Time = E/T

Voltage = Energy Moving Unit Charge

Current = Total Charge / Time

=

=

= = =2 =2/

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EE292 Figure PA1.1: Strain Sensor

Fi 1 39 A i it i ti f lt d

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EE292Figure 1.39 A circuit consisting of a voltage source and aresistance.

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EE292 Figure 1.40 Circuit for Example 1.6.

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EE292 Figure 1.41 Circuit for Example 1.7.

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EE292

Table T1.1

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EE292

Table T1.1 (continued)

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EE292_ch01_v2