ELECTRICAL SCIENCE Module 1 - Energy.gov

DOE FundamentalsELECTRICAL SCIENCEModule 1Basic Electrical Theory

Basic Electrical TheoryTABLE OF CONTENTST able of Co nte ntsTABLE OF CONTENTS . iLIST OF FIGURES .ivLIST OF TABLES .viREFERENCES . viiOBJECTIVES . viiiTERMINAL OBJECTIVE . viiiENABLING OBJECTIVES . viiiATOM AND ITS FORCES . 1The Atom . 1Electrostatic Force . 2The First Law of Electrostatics . 3Electrostatic Field . 3Potential Difference . 5Free Electrons . 6Summary . 8ELECTRICAL TERMINOLOGY . 9Conductors . 9Insulators . 9Resistors. 9Voltage . 10Current. 10Real and Ideal Sources . 12Summary . 12UNITS OF ELECTRICAL MEASUREMENT . 13System Internationale (SI) Metric System . 13Voltage . 14Current. 14Resistance . 14Ohm's Law . 14iES-01

Basic Electrical TheoryConductance . 16Power . 16Inductance . 17Capacitance . 17Summary . 18METHODS OF PRODUCING VOLTAGE (ELECTRICITY) . 19Electrochemistry . 19Static Electricity . 20Magnetic Induction. 21Piezoelectric Effect . 21Thermoelectricity . 22Photoelectric Effect . 23Thermionic Emission . 24Summary . 26MAGNETISM . 27Magnetism . 27Magnetic Flux . 29Magnetic Flux Density . 29Magnetic Materials. 29Electromagnetism . 30Polarity of a Single Conductor . 31Magnetic Field and Polarity of a Coil . 31Magnetomotive Force . 32Field Intensity. 33Reluctance. 34Summary . 35MAGNETIC CIRCUITS . 36Magnetic Circuits . 36BH Magnetization Curve . 37Hysteresis . 39Magnetic Induction. 39iiES-01

Basic Electrical TheoryFaraday's Law of Induced Voltage . 40Lenz's Law . 41Summary . 42ELECTRICAL SYMBOLS . 43Symbols . 43Appendix A: Metric System and Powers of Ten . A1Metric System . A1Metric Prefixes . A2Powers of Ten. A3iiiES-01

Basic Electrical TheoryLIST OF FIGURESFigure 1The Atom . 1Figure 2The Carbon Atom . 2Figure 3Electrostatic Force . 2Figure 4Electrostatic Field . 3Figure 5Electrostatic Field Between Two Charges of Opposite Polarity . 4Figure 6Electrostatic Field Between Two Charges of Like Polarity . 4Figure 7Potential Difference Between Two Charged Objects . 5Figure 8Energy Shells and Electron Quota . 6Figure 9Electron Flow Through a Copper Wire with a Potential Difference . 11Figure 10Potential Difference Across a Conductor Causes a Current to Flow . 11Figure 11Voltaic Chemical Cell . 20Figure 12Static Electricity . 20Figure 13Generator - Electromagnetic Induction . 21Figure 14Pressure Applied to Certain Crystals Produce an Electric Charge . 22Figure 15Heat Energy Causes Copper to Give up Electrons to Zinc . 23Figure 16Producing Electricity from Light Using a Photovoltaic Cell . 24Figure 17Vacuum Tube Diode . 25Figure 18Electron Spinning Around Nucleus Produces Magnetic Field . 27Figure 19Magnetic Domains . 28Figure 20The Law of Magnetic Attraction and Repulsion . 28Figure 21The Magnetic Field Produced by Current in a Conductor . 31Figure 22Left-hand Rule for Current Carrying Conductors . 31Figure 23Left-hand Rule for Coils . 32Figure 24Left-hand Rule to Find North Pole of an Electromagnet . 33Figure 25Different Physical Forms of Electromagnets . 35Figure 26Magnetic Current with Closed Iron Path . 38Figure 27Typical BH Curve for Two Types of Soft Iron . 39ivES-01

Basic Electrical TheoryFigure 28Hysteresis Loop for Magnetic Materials . 41Figure 29Induced EMF . 42Figure 30Electrical Symbols . 46vES-01

Basic Electrical TheoryLIST OF TABLESTable A-1Base Units of the International Metric System . A-1Table A-2Supplementary SI Units . A-2Table A-3Derived SI Units . A-3Table A-4Metric Prefixes Used in Electricity . A-4Table A-5Powers of 10 . A-5Table A-6Metric Prefixes Expressed as Powers of 10 . A-8viES-01

Basic Electrical TheoryREFERENCES Gussow, Milton, Schaum's Outline of Basic Electricity, 2nd Edition, McGraw-Hill. Academic Program for Nuclear Power Plant Personnel, Volume I & II, Columbia,MD: General Physics Corporation, Library of Congress Card #A 326517, 1982. Sienko and Plane, Chemical Principles and Properties, 3rd Edition, McGraw-Hill. Nasar and Unnewehr, Electromechanics and Electric Machines, 2nd Edition, JohnWiley and Sons. Nooger and Neville Inc., Van Valkenburgh, Basic Electricity, Vol. 5, Hayden BookCompany. Lister, Eugene C., Electric Circuits and Machines, 7th Edition, McGraw-Hill. Croft, Hartwell, and Summers, American Electricians’ Handbook, 16th Edition,McGraw-Hill. Mason, C. Russel, The Art and Science of Protective Relaying, John Wiley andSons. Mileaf, Harry, Electricity One - Seven, Revised 2nd Edition, Hayden BookCompany. Buban and Schmitt, Understanding Electricity and Electronics, 3rd Edition,McGraw-Hill. Kidwell, Walter, Electrical Instruments and Measurements, McGraw-Hill.viiES-01

Basic Electrical TheoryOBJECTIVESTERMINAL OBJECTIVE1.0Given a simple electrical circuit, APPLY basic electrical theory fundamentalprinciples to describe circuit operation.ENABLING OBJECTIVES1.1DESCRIBE the following terms:a. Electrostatic forceb. Electrostatic fieldc. Potential differenced. Electromotive force (EMF)e. Ion charge1.2DEFINE the following terms:a. Conductorb. Insulatorc. Resistord. Electron current flowe. Conventional current flowf. Direct current (DC)g. Alternating current (AC)h. Ideal sourcei. Real source1.3DESCRIBE the following electrical parameters, including the unit ofmeasurement and the relationship to other parameters.a. Voltageb. Currentc. Resistanced. ConductanceviiiES-01

Basic Electrical Theorye. Powerf. Inductanceg. Capacitance1.4Given any two of the three component values of Ohm's Law, DETERMINE theunknown component value.1.5DESCRIBE how the following methods produce a voltage:a. Electrochemistryb. Static electricityc. Magnetic Inductiond. Piezoelectric effecte. Thermoelectricityf. Photoelectric effectg. Thermionic emission1.6DEFINE the following terms:a. Magnetic fluxb. Magnetic flux densityc. Weberd. Permeabilitye. Magnetomotive force (mmf)f. Ampere turnsg. Field intensityh. Reluctance1.7DESCRIBE the following materials as they relate to permeability, including anexample and an approximate relative permeability.a. Ferromagnetic materialsb. Paramagnetic materialsc. Diamagnetic materials1.8EXPLAIN the physical qualities of a simple magnetic circuit, includingrelationships of qualities and units of measurements.1.9Given the physical qualities of a simple magnetic circuit, CALCULATE theunknown values.ixES-01

Basic Electrical Theory1.10DESCRIBE the shape and components of a BH magnetization curve.1.11EXPLAIN the cause of hysteresis losses.1.12Given Faraday's Law of induced voltage:a. DESCRIBE how varying parameters affect induced voltage.b. CALCULATE voltage induced in a conductor moving through a magneticfield.1.13STATE Lenz's Law of induction.1.14Given a standard electrical symbol, IDENTIFY the component that the symbolrepresents. The symbols will be for the following components:a.Resistorm. Fuseb.Capacitorn.Junctionc.Inductoro.AC voltage err.Wattmeterg.Switchs.Relay operated contactsh.Transistort.Potential transformeri.Rheostatu.Current transformerj.Diodev.Wye (Y) connectionk.Ground connectionsw. Delta (Δ) connectionl.Vacuum tubex.Light bulby.BatteryxES-01

Basic Electrical TheoryAtom and its ForcesATOM AND ITS FORCESWhat is electricity? Electricity is defined as "the flow of electrons through simplematerials and devices" or "that force which moves electrons." Scientists thinkelectricity is produced by very tiny particles called electrons and protons. Theseparticles are too small to be seen, but exist as subatomic particles in the atom.To understand how they exist, you must first understand the structure of theatom.EO 1.1DESCRIBE the following terms:a. Electrostatic forceb. Electrostatic fieldc. Potential differenced. Electromotive force (EMF)e. Ion chargeThe AtomElements are the basicbuilding blocks of all matter.The atom is the smallestparticle to which an elementcan be reduced while stillkeeping the properties of thatelement. An atom consists ofa positively charged nucleussurrounded by negativelycharged electrons, so that theatom as a whole is electricallyneutral. The nucleus iscomposed of two kinds ofsubatomic particles, protonsand neutrons, as shown inFigure 1. The proton carries asingle unit positive charge equal in magnitude to the electron charge. The neutron isslightly heavier than the proton and is electrically neutral, as the name implies. Thesetwo particles exist in various combinations, depending upon the element involved. The1ES-01

Basic Electrical TheoryAtom and its Forceselectron is the fundamental negative charge (-) of electricity and revolves around thenucleus, or center, of the atom in concentric orbits, or shells.The proton is the fundamental positivecharge ( ) of electricity and is locatedin the nucleus. The number of protonsin the nucleus of any atom specifiesthe atomic number of that atom or ofthat element. For example, the carbonatom contains six protons in itsnucleus; therefore, the atomic numberfor carbon is six, as shown in Figure 2.In its natural state, an atom of anyelement contains an equal number ofelectrons and protons. The negativecharge (-) of each electron is equal inmagnitude to the positive charge ( ) ofeach proton; therefore, the twoopposite charges cancel, and the atomis said to be electrically neutral, or inbalance.Electrostatic ForceOne of the mysteries of the atom is that the electron and the nucleus attract each other.This attraction is called electrostatic force, the force that holds the electron in orbit. Thisforce may be illustrated with lines as shown in Figure 3.Figure 3 Electrostatic Force2ES-01

Basic Electrical TheoryAtom and its ForcesWithout this electrostatic force, the electron, which is traveling at high speed, could notstay in its orbit. Bodies that attract each other in this way are called charged bodies. Asmentioned previously, the electron has a negative charge, and the nucleus (due to theproton) has a positive charge.The First Law of ElectrostaticsThe negative charge of the electron is equal, but opposite to, the positive charge of theproton. These charges are referred to as electrostatic charges. In nature, unlike charges(like electrons and protons) attract each other, and like charges repel each other. Thesefacts are known as the First Law of Electrostatics and are sometimes referred to as thelaw of electrical charges. This law should be remembered because it is one of the vitalconcepts in electricity.Some atoms can lose electrons and others can gain electrons; thus, it is possible totransfer electrons from one object to another. When this occurs, the equal distribution ofnegative and positive charges no longer exists. One object will contain an excess ofelectrons and become negatively charged, and the other will become deficient inelectrons and become positively charged. These objects, which can contain billions ofatoms, will then follow the same law of electrostatics as the electron and protonexample shown above. The electrons that can move around within an object are said tobe free electrons and will be discussed in more detail in a later section. The greater thenumber of these free electrons an object contains, the greater its negative electriccharge. Thus, th

Module 1 Basic Electrical Theory . Basic Electrical Theory i ES-01 TABLE OF CONTENTS Table of Co nte nts . 1.0 Given a simple electrical circuit, APPLY basic electrical theory fundamental principles to describe circuit operation. ENABLING OBJECTIVES 1.1 DESCRIBE the following terms: