《通信电子线路》课程教学资源（教材文献）Circuit Analysis Theory And Practice（PDF电子书）

26Chapter1IntroductionIron-coreinductor1SwitchResistorResistorCapacitorJeltBatteryFIGURE1-1150.Drawtheschematicdiagramfora simpleflashlight1.8CircuitAnalysisUsingComputers51. Many electronic and computer magazines carry advertisements for com-puter software tools such as PSpice, SpiceNet, Mathcad, MLAB,Matlab,MapleV,plus others.Investigate a few of these magazines in your school'slibrary;by studying such advertisements,you can gain valuable insight intowhat modern software packages are able to do

50. Draw the schematic diagram for a simple flashlight. 1.8 Circuit Analysis Using Computers 51. Many electronic and computer magazines carry advertisements for com￾puter software tools such as PSpice, SpiceNet, Mathcad, MLAB, Matlab, Maple V, plus others. Investigate a few of these magazines in your school’s library; by studying such advertisements, you can gain valuable insight into what modern software packages are able to do. 26 Chapter 1 ■ Introduction ￾￾￾ Switch Capacitor Resistor Resistor Iron-core inductor ￾￾￾
Jolt Battery FIGURE 1–11

27Answers toIn-Process Learning ChecksIn-Process Learning Check 1ANSWERSTOIN-PROCESSLEARNINGCHECKS1. One2.1280cm3. m/sb. 1.53mV4.a.4.27 sc.1.23ms5.a.1.8×10*=18×1035=0.36×106b.36×104= 3.6×105c.4.45×102=44.5×10d.27×10-6=2.7×10-5b. 980 μV6.a.0.752mAc.400 μs=0.4ms

Answers to In-Process Learning Checks 27 In-Process Learning Check 1 1. One 2. 1280 cm 3. m/s 4. a. 4.27 s b. 1.53 mV c. 1.23 ms 5. a. 1.8
104 18
103 b. 36
104 3.6
105 0.36
106 c. 4.45
102 44.5
101 d. 27
106 2.7
105 6. a. 0.752 mA b. 980 mV c. 400 ms 0.4 ms ANSWERS TO IN-PROCESS LEARNING CHECKS

Voltage and Current2OBJECTIVESCircuit BreakerConductorAfter studying this chapter,you will beCoulombabletoCoulomb'sLaw.describe the makeup of an atom,Currentexplain the relationships berweenvalence shells, free electrons, and con-Electric Chargeduction,Electrondescribe thefundamental (coulomb)Free Electronsforce within an atom,and theenergyFuserequired to create free electrons,Insulatordescribe what ions are and how they areloncreated,Neutrondescribe the characteristics of conduc-Polaritytors,insulators,and semiconductors,Potential Difference.describethecoulombasameasureofcharge,Protondefinevoltage,SemiconductorShelldescribe how a battery“creates" volt-age,Switchexplain current as a movement of chargeValenceand how voltage causes current in a con-Voltductor,describe important battery types andOUTLINEtheir characteristics,AtomicTheoryReviewdescribe howto measurevoltageandThe Unit of Electrical Charge: Thecurrent.CoulombVoltageKEYTERMSCurrentAmperePractical DC Voltage SourcesAtomMeasuring Voltage and CurrentBatterySwitches, Fuses, and Circuit BreakersCell

OBJECTIVES After studying this chapter, you will be able to • describe the makeup of an atom, • explain the relationships between valence shells, free electrons, and con￾duction, • describe the fundamental (coulomb) force within an atom, and the energy required to create free electrons, • describe what ions are and how they are created, • describe the characteristics of conduc￾tors, insulators, and semiconductors, • describe the coulomb as a measure of charge, • define voltage, • describe how a battery “creates” volt￾age, • explain current as a movement of charge and how voltage causes current in a con￾ductor, • describe important battery types and their characteristics, • describe how to measure voltage and current. KEY TERMS Ampere Atom Battery Cell Circuit Breaker Conductor Coulomb Coulomb’s Law Current Electric Charge Electron Free Electrons Fuse Insulator Ion Neutron Polarity Potential Difference Proton Semiconductor Shell Switch Valence Volt OUTLINE Atomic Theory Review The Unit of Electrical Charge: The Coulomb Voltage Current Practical DC Voltage Sources Measuring Voltage and Current Switches, Fuses, and Circuit Breakers Voltage and Current 2

basic electric circuit consisting of a source of electrical energy,a switch, aCHAPTERPREVIEWload, and interconnecting wire is shown in Figure 2-1.When the switch isclosed, current in the circuit causes the light to come on. This circuit is represen-tativeof manycommoncircuitsfound in practice,includingthoseofflashlightsand automobileheadlight systems.We will use it to help develop an understand-ing of voltage and current.CurrentSwitchLamp(load)InterconnectingwireBattery(source)FIGURE 2-1 A basic electric circuitElementary atomic theory shows that the current in Figure 2-1 is actually aflow of charges. The cause of their movement is the voltage"of the source.While in Figure 2-1 this source is a battery, in practice it may be any one of anumber of practical sources including generators, power supplies, solar cells, andso on.In this chapter we look at the basic ideas of voltage and current.We beginwith a discussion of atomic theory.This leads us tofree electrons and the idea ofcurrent as a movement of charge.The fundamental definitions of voltage andcurrent are then developed.Following this, we look at a number of common volt-age sources.The chapter concludes with a discussion of voltmeters and amme-ters and the measurement of voltage and current in practice.29

Abasic electric circuit consisting of a source of electrical energy, a switch, a load, and interconnecting wire is shown in Figure 2–1. When the switch is closed, current in the circuit causes the light to come on. This circuit is represen￾tative of many common circuits found in practice, including those of flashlights and automobile headlight systems. We will use it to help develop an understand￾ing of voltage and current. 29 CHAPTER PREVIEW Elementary atomic theory shows that the current in Figure 2–1 is actually a flow of charges. The cause of their movement is the “voltage” of the source. While in Figure 2–1 this source is a battery, in practice it may be any one of a number of practical sources including generators, power supplies, solar cells, and so on. In this chapter we look at the basic ideas of voltage and current. We begin with a discussion of atomic theory. This leads us to free electrons and the idea of current as a movement of charge. The fundamental definitions of voltage and current are then developed. Following this, we look at a number of common volt￾age sources. The chapter concludes with a discussion of voltmeters and amme￾ters and the measurement of voltage and current in practice. FIGURE 2–1 A basic electric circuit. Switch Current Lamp (load) ￾￾ Interconnecting wire
Jolt Battery (source)

30Chapter2Voltage andCurrentThe Equations of Circuit TheoryPUTTING IT INPERSPECTIVEIN THIS CHAPTER you meet thefirst of the equations and formulas that we useto describe the relationships of circuit theory. Remembering formulas is madeeasier if you clearly understand the principles and concepts on which they arebased. As you may recall from high school physics, formulas can come aboutin only one of three ways, through experiment, by definition, or by mathemati-cal manipulation.ExperimentalFormulasCircuit theory rests on afewbasic experimental results.These are results thatcan be proven in no other way: they are valid solely because experiment hasshown themto betrue.Themostfundamental of these are called"laws."Fourexamples are Ohm's law,Kirchhoff's current law, Kirchhoff's voltage law,andFaraday's law. (These laws will be met in various chapters throughout thebook.)When you seea formula referred toas a law or an experimental result,remember that it is based on experiment and cannot be obtained in any otherway.DefinedFormulasSome formulas are created by definition, i.e., we make them up. For example.there are 60 seconds in a minute because we definethe second as 1/60 of aminute.From this we get theformula fe = 60 X tmin.Derived FormulasThis type of formula or equation is created mathematically by combining ormanipulatingotherformulas.In contrasttotheother twotypes offormulas,theonlywaythataderivedrelationshipcanbeobtainedisbymathematicsAn awareness of where circuit theory formulas come from is important toyou.This awareness not only helps you understand and remember formulas, ithelps you understand the very foundations of the theory--the basic experimen-tal premises upon which it rests, the important definitions that have been made,and the methods by which these foundation ideas have been put together.Thiscan help enormously in understanding and remembering concepts.2.1Atomic TheoryReviewThebasicstructureof an atom is shown symbolicallyinFigure2-2.It con-sists of a nucleus of protons and neutrons surrounded by a group of orbitingelectrons.Asyou learned in physics,the electrons are negativelycharged(-),while the protons are positively charged (+).Each atom (in its normalstate)has an equal number of electrons andprotons,and sincetheirchargesare equal and opposite,they cancel, leaving the atom electricallyneutral, i.e.,with zero net charge.The nucleus, however, has a net positive charge, sinceit consists of positively charged protons and uncharged neutrons

2.1 Atomic Theory Review The basic structure of an atom is shown symbolically in Figure 2–2. It con￾sists of a nucleus of protons and neutrons surrounded by a group of orbiting electrons. As you learned in physics, the electrons are negatively charged (
), while the protons are positively charged (). Each atom (in its normal state) has an equal number of electrons and protons, and since their charges are equal and opposite, they cancel, leaving the atom electrically neutral, i.e., with zero net charge. The nucleus, however, has a net positive charge, since it consists of positively charged protons and uncharged neutrons. 30 Chapter 2 ■ Voltage and Current The Equations of Circuit Theory IN THIS CHAPTER you meet the first of the equations and formulas that we use to describe the relationships of circuit theory. Remembering formulas is made easier if you clearly understand the principles and concepts on which they are based. As you may recall from high school physics, formulas can come about in only one of three ways, through experiment, by definition, or by mathemati￾cal manipulation. Experimental Formulas Circuit theory rests on a few basic experimental results. These are results that can be proven in no other way; they are valid solely because experiment has shown them to be true. The most fundamental of these are called “laws.” Four examples are Ohm’s law, Kirchhoff’s current law, Kirchhoff’s voltage law, and Faraday’s law. (These laws will be met in various chapters throughout the book.) When you see a formula referred to as a law or an experimental result, remember that it is based on experiment and cannot be obtained in any other way. Defined Formulas Some formulas are created by definition, i.e., we make them up. For example, there are 60 seconds in a minute because we define the second as 1/60 of a minute. From this we get the formula tsec 60  tmin. Derived Formulas This type of formula or equation is created mathematically by combining or manipulating other formulas. In contrast to the other two types of formulas, the only way that a derived relationship can be obtained is by mathematics. An awareness of where circuit theory formulas come from is important to you. This awareness not only helps you understand and remember formulas, it helps you understand the very foundations of the theory—the basic experimen￾tal premises upon which it rests, the important definitions that have been made, and the methods by which these foundation ideas have been put together. This can help enormously in understanding and remembering concepts. PUTTING IT IN PERSPECTIVE