This document defines many basic electronics terms. It provides definitions for terms like alternating current, analog, amplifier, battery, capacitor, circuit, conductor, current, digital, diode, direct current, electromagnet, electronics, frequency, ground, inductance, integrated circuit, insulator, resistance, semiconductor, transistor, voltage, and wire. The definitions are provided in an electronics context to help one study basic electronics concepts and components.

1. Basic ElectronicsTermsandDefinitions
The followingisalistof manyof the termsone wouldencounterinthe studyof basicelectronics. The termsare definedin
theirelectronicscontext.
AlternatingCurrent (ac) Currentfroma powersource that changespolarityperiodically.
Alternator A device thatsuppliesalternatingcurrent.
American wire gauge (AWG) A standardforwire sizes,withthe smallestbeingdesignatedasforty(40) and the largestas
fouraught (4/0).
Ammeter An instrumentusedformeasuringcurrent.
Ampacity The current–carryingcapacity of conductorsin amperes.
Amperage (A) The amountof electriccurrentinamperes.
Ampere (A) The unitof measurementforcurrent.One ampere isthatcurrentwherebyone coulomb of charge passes
througha pointin one second.Namedfor André Ampere.
Ampere-hour(Ah) Unit of measurementforcell orbatterycapacity. One Ah generally meansthata currentof one amp has
beenflowingforone hour.
Amplifier Anelectroniccircuitthatboostthe voltage and/orthe currentlevel of a signal.
Analog Generallyreferstosignalsthathave manydiscrete valuesversusdigital binarysignal thathave onlytwostates.Also,
referstothe branchof electronicsdealingwithsuchsignals andtheircircuits. The termlinearisanothertermoftenusedfor
such circuitsandsignals.
Analog-to-digital converter(A/D) A circuitor devise usedtoconvertananalogsignal toa digital form.
AND gate or logic Generatesalogic1 onlyif all of itstwoor more inputsare 1.
Apparent power The product of voltage timescurrentina circuitcontainingreactancesandmeasuredinvolt-amps.
Armature The movingpartof a motor or generator.
Autotransformer A powertransformerhavingone continuouswindingthatistapped.
Ballast A device usedtoprovide startingcurrentforcertaintypesof lamps(fluorescent).
Battery A direct-currentpowersource consistingof twoor more cells.
Binary Inelectronics,anumbersystemthathastwo as itsbase;therefore anypositionhasonlytwopossible values,0or 1. A
signal thathas onlytwopossible statesatanyinstance.
Bipolar junctiontransistor (BJT) A transistortype havingtwoPN junctions,configuredasNPN or PNP. May be usedasan
amplifierorswitch.
Bit A single binarydigit,canbe eithera0 or 1.
Bridge See Wheatstone bridge
Brush A conductive blockusedtomake slidingcontactwithanarmature.
Byte A groupof eightbinarybits,commonlyusedto representdigitaldata.
Cable A strandedconductoror group of individual conductorsinsulatedfromeachother.
Capacitance (C) The abilityof twoconductorsseparatedbyan
insulatortostore an electrical charge;measuredinfarads(F).
Capacitive reactance (XC) The oppositionthatacapacitor
offerstoalternatingcurrent. Thisopposition,inthe formof a
counterelectromotive force (cemf),isexpressedinohms.
Capacitor A device designedtoprovide aspecificamountof
capacitance.
Cell A device thattransformsone formof energyintoelectrical energy. Anexample wouldbe achemical drycell
commonlyusedinflashlights(D,C,AA,AAA) andotherelectricdevices. These are oftenreferredtoas batteries.
Central processingunit (CPU) The part of a computerthat performsthe arithmetic,logic,andcontrol functions.
Circuit Anarrangementorconnectionof circuitdevicesandcomponentstoperformaspecificobjective. Inthe simplest
formit wouldrequire anenergysource,aloadto transformthe energyintothe desiredtask,andconductorstoconnectthe
source to the load. Inmost applicationsacontrol device (switch) wouldbe includedandmayalsoinclude aprotective device.
Commonexample of asimple circuitwouldbe aflashlight.
Circuit breaker A circuitprotectiondevice thatopensthe circuitautomaticallywhenanoverloadorshortcircuitoccurs.
Closedcircuit A circuitthat providesacomplete pathforcurrent.
Coil A wound spiral of twoor more turns of insulatedwire,usedtointroduce inductance intoacircuit,produce amagnetic
fieldfromcurrentflow,ortorespondto a changingmagneticfieldbyproducingavoltage ormechanical motion.
Component/s In electronics, ageneral termtorefertoa part or parts of a circuitwithoutreference tospecificnames.
Commutator A cylindrical arrangementof insulatedmetal barsconnectedtothe armature coilsof a direct-currentelectric
motor or generator,providingaunidirectional currentfromthe generatorora reversal of currentintothe coilsof the motor.
Conductance (G) The abilityof aconductor to allow the flow of electrons.MeasuredinSiemens(S). The reciprocal of
resistance.

2. Conductor A low-resistance materialtoprovide apathfor current. Used to interconnectcomponentsinacircuit.
Conventional current A directionflow assignmentthathascurrentflowingfrompositive tonegative.
Coulomb Base unitof electrical charge equal to6.25 X 1018
electrons.NamedforCharlesCoulomb,the Frenchphysicistwho
pioneeredresearchintomagnetismandelectricity.He alsoformulatedCoulomb'slaw whichstatesthatthe force of attraction
or repulsionbetweentwochargedbodiesisequal tothe productof the two chargesand isinverselyproportionaltothe square
of the distance betweenthem. F= Q1 x Q2/d2
Crystal A natural or syntheticcrystalline material havingpiezoelectricproperties. Asatransducer,usedtoconvertdynamic
pressures(vibrations)toac electricityorchange ac electricityintovibrations.
Current (I) The rate of flowof electronsthroughaconductor or component;measuredinamperes. The symbol (I) standsfor
intensityof the electronflow.
Cycle One complete wave of alternatingvoltage orcurrent.
Dielectric A nonconductorof electricity.Aninsulatorthatiscapable of concentratingelectricfields.
Difference ofpotential See electromotive force and voltage.
Digital Generallyinelectronics,referstosignals,devices,orcircuitsthatare binary,meaningtheyonlyhave twostates(high
or low,1 or 0, on or off). The branch of electronicsdealingwithsuchsignalsandtheircircuits.
Digital-to-analogconverter(D/A) A circuitthat convertsa binarysignal toan equivalentanalogform.
Diode A semiconductordevice thatonlyallowscurrenttopassthroughit inone direction,cathode toanode. Also,a
classificationof semiconductordeviceshavingonlyone junction. Examplesinclude:rectifier,zener,varactor,andtunnel
diodes.
Direct Current (dc) Currentfrom a powersource that continuallyflowsinthe same direction. Anelectrical source of
constantpolarity.
Duty Cycle The ratio of pulse widthtoperiod,indicatesthe percentage of time apulse ispresentduringacycle.
Electricity The physical phenomenaarisingfromthe behaviorof electronsandprotonsthatiscausedby the attractionof
particleswithoppositecharges andthe repulsionof particleswiththe same charge. The physical science of such
phenomena. Also,electriccurrentusedorregardedas a source of power.
Electric energy The energycarriedbyfree electronsfromasource to a load.Also,the potential energyof astationary
charge.
Electric power(P) The rate at whichenergyisconsumedinacircuit or load. Measuredinwatts(W).
Electrolyte A chemical solutionusedincellsandsome capacitorstoproduce an electricallyconductive medium.
Electrolyticcapacitor A capacitor whose dielectricisformedthroughthe reactionof anelectrolyte anditselectrodes.
Electromagnet A device thatproducesa magneticfieldasthe resultof currentflow throughacoil of wire.
Electromechanical A classificationof actionsordeviceswherebyamechanical actioniscausedbythe forcesof attractionor
repulsioncreatedwhencurrentflowgeneratesmagneticfields(electromagnetic).
Electromotive Force (emf) The force or electrical pressure thathasthe potential tocause electronflow inacircuit. Also
calledvoltage,potential difference ordifferenceofpotential. Measuredinvolts(V).
Electrostatic field Anelectricfieldproducedbystationarycharges.
Farad (F) The basicunitof measurementforcapacitance. One faradisthat capacitance that will store one coulombof
charge whenthe chargingforce isone volt. Since the farad isa verylarge unit,capacitance will more commonlybe expressed
as microfarad(uF) or picofarad (pF) values.NamedforMichael Farady, the Britishphysicistandchemistwhodiscovered
electromagneticinductionandproposedthe fieldtheorylaterdevelopedbyMaxwell andEinstein.
FieldEffectTransistor (FET) A transistortype thatusesvoltage tocontrol currentthroughthe device. See JFETandMOSFET.
Filter A circuitdesignedtopassa specificfrequencyrange while rejectingall others.
Flux Generallyreferstoamagneticline of force butmay alsodescribe anelectricline of force.
Frequency The numberof cyclespersecondfora periodicwaveform. Measuredinhertz(Hz).
Fuse A protective device designedtointerruptcurrentflow (open) throughacircuitwhencurrentexceedsarated value.
Gate A logiccircuitperformingaspecificlogicfunction.SeeAND,OR,NAND,ORandNOT.
Gauss A unitof measurementformagneticfield.
Generator A device thatconvertsmechanical energytoelectricalenergy.
Ground The commonreturnpath for currentin an electrical circuit. Servesasa reference pointformeasuringall other
potentialsinacircuit. Generallyassumedtobe atzero potential withrespecttothe earth. Otherthan earthreferencesmay
be usedsuch as the chassisof an automobile(chassisground)orsome arbitrarypointina circuit(circuitground) like the
negative side of the powersource.
Heat sink A device attachedtoa componenttoaidin the dissipationof heat.
Henry (H) The unitof inductance inwhichaninducedelectromotive force of one voltisproducedwhenthe currentisvaried
at the rate of one ampere persecond. NamedforJosephHenry,anAmericanphysicistwhoperformedextensive studiesof
electromagneticphenomena.
Hertz (Hz) A unitof frequencyequal toone cycle persecond.Namedfor HeinrichHertz, a Germanphysicistwhowasthe
firstto produce radiowavesartificially.
Impedance (Z) Oppositiontocurrentflowfromthe combinedeffectsof resistance andreactance measuredinohms(S).
Inductance (L) The propertyof a circuitthat opposesachange in current.Also,the propertyof a circuitto store energyinthe
formof a magneticfieldandrelease itbackintothe circuitat a latertime.
Inductive Reactance (XL) The oppositionthataninductorofferstoalternatingcurrent. Thisopposition,inthe formof a
counterelectromotive force (cemf),isexpressedinohms.
Inductor An electrical device designedtoprovide aspecificamountof inductance;measuredinhenrys(H).
Insulation Nonconductive materialusedtocoverwiresandcomponentstopreventshockandshortcircuits.
Insulator A material thathasa highresistance tocurrentflow.

3. IntegratedCircuit (IC) The placementof numerouscomponentsandcircuitsonto a siliconchip.
Internal resistance The resistance withinapowersource.
Inverter A logicdevise (NOTfunction) whoseoutputisalwaysopposite the input. Alsoreferstoa devise thatconvertsdcto
ac.
Junction FieldEffectTransistor (JFET) A transistortype made by diffusingagate regionintoa channel region. Voltage
appliedtothe gate controlscurrentin the channel byeitherdepletingorenhancingthe channel.
Joule The basicunitof electrical,mechanical,andthermal energy. Asaunitof electrical energyitisequal tothe energy
carriedby 1 coulombof charge beingpropelledbyanelectromotive force of 1volt. NamedforJames Joule,the British
physicistwhoestablishedthe mechanical theoryof heat anddiscoveredthe firstlaw of thermodynamics.
Kilo(k) Metricprefix forunitsof measurementequal tothousands(1000 or 103
). As an example:1kilohertz(kHz)equals
1000hz.
Kilowatthour (kWh) Unit of energyconsumptionequalto1000 watt-hoursorthe energyconsumedatthe rate toone
kilowatt(kW) fora time of one hour. Equivalentto3,600,000 joules. Generallyusedtospecifyalarge energyconsumption
overa specifictime interval. Residential energyisusuallypricedatthe numberof kilowatt-hoursusedforamonth.
Kirchhoff, Gustav Robert The German physicistnotedforhisresearchinspectrumanalysis,optics,andelectricity.
DevelopedfundamentalDCcircuitlawsdealingwithcurrentcharacteristicsinaparallel circuitandvoltage characteristicsina
seriescircuit.His currentlaw statesthatthe currententeringaconnectionhasto equal the currentleavingthatconnection,
and that the sumof the loadcurrentshas to equal the source current(or sum of source currents for multiple parallel sources)
(IT = I1+I2+------+IN). Hisvoltage law statesthat aroundany closedloopof seriesconnectedcomponents,the sumof the voltage
dropsmust equal the source voltage (orsumof source voltagesformultiple seriesconnected sources.(VT =V1+V2+------+VN).
Lamp A lightproducingdevice consistingof afilamentplacedinavacuum.
Law of magneticpoles Like polesrepel,unlike polesattract.
Liquidcrystal display(LCD) A displaytype usingchangesinreflectivitytogenerate variouscharacters.
Lenz’sLaw Basic lawof electromagneticinductionwhichstatesthataninducedvoltage willhave apolaritythatopposesthe
currentchange thatproducedit.
Light-emittingdiode (LED) A semiconductordiode that emitslightascurrentflowsfromthe cathode to the anode acrossits
PN junction.
Linear A circuitor componentwhere the outputisa straightline (directproportion) functionof the input.
Load A device orapparatusthat usesthe energyof a circuit to performwork. May alsoreferto the powerusedbya device,
machine,ora combinationof many.
Magnet Anobjectwhichproducesa magneticfieldinthe surroundingspace.
Magneticfield The detectable magneticfluxissuingfromamagnet or electromagnet.
Magneticpoles The two pointsof strongestconcentrationof magneticflux aroundamagnetor electromagnet. By
assignmentthe flux leavesthe northpole andreturnstothesouthpole.
Magneticsaturation The pointwhere an increase inmagneticforce producesnofurthermagneticeffectinamagnetic
material. The material canhave no furtherincrease influx.Iron,nickel,cobalt,andtheiralloysare consideredtobe magnetic
materials.
Magnetism The physical phenomena exhibitedbymagnetsandelectriccurrentflow thatisrepresentedbylinesof force.
Mega (M) Prefix forunitsof measurementequal tomillions(1,000,000 or 106
).
Memory The part of a computingdevice where dataandinstructionsare stored.
See RAMand ROM.
Metal oxide field-effecttransistor(MOSFET) Alsocalledinsulatedgate fieldeffecttransistor(IGFET). A transistortype that
usesan electricfieldtocontrol conduction.
Micro (u) Prefix forunitsof measurementequal tomillionths (1/1,000,000 or 10-6
).
Microprocessor A CPU that is manufacturedona single integrated-circuit (IC) chip.
Milli (m) Prefix forunitsof measurementequal tothousandths(1/1000or 10-3
).
Modem Abbreviationformodulator-demodulator. A device thatconvertsdatafromone forminto another,asfromone
formusable indata processingtoanotherformusable intelephonictransmission.
Multimeter Aninstrumentthatcan measure current,voltage,andresistanceonvariousranges. Manymultimeters can
measure othercircuitvaluessuchasfrequencyandcapacitance. May have digital (DMM) or analogdisplays(VOM).
NAND gate or logic Standsfor NOT-AND. Givesaninvertedoutputof ANDlogic.
Negative For sources,impliesthe terminal thathas anexcessof electrons. Also,canimplythe polarityof apointina circuitin
respectto some otherpoint.
Nonlinear A circuit or componentwhose outputversusinputgraphisnota straightline.
NOR gate or logic Stands forNOT-OR. Givesaninvertedoutputof ORlogic.
North-seekingpole That pole of a magneticwhichpointstothe earth’snorthpole whenfree toturn.
Norton’s theorem A methodof reducingacomplex networkof bilateral(conductsequallywellinbothdirections)
componentstoone currentsource and one shuntresistance acrossthe loadterminals.
Ohm (S) The unitof measurementforresistance. NamedforGeorgSimonOhm,the Germanphysicistnotedforhis
contributionstomathematics,acoustics,andthe measurementof electrical resistance. One ohmisthatresistance thatlimits
the current to one ampere whenapotential of one voltexistacrossitsterminals.
Ohm’s law Verybasiccircuitlaw thatdefinesthe relationshipsbetweencurrent,voltage,andresistance inaDC circuit.
Ohm’slawstatesthat currentis directlyproportionaltovoltage andinverselyproportionaltoresistance.(I=V/R) The other
forms of the formulaare V = IR and R = V/I.
Ohmmeter An instrumentformeasuringresistance.

4. Operational Amplifier(OpAmp) A highlystable directcoupledamplifierresistanttooscillation. Maybe packagedinan IC
format.
OR gate or logic Generatesalogic1 if any one of itstwo or more inputsare 1.
Oscillator A circuitthat convertsdc powerintoac signalswithconstantfrequency. Also,aninstrumentthatgenerates ac
signalswhose frequencyandamplitude canbe varied. These are alsoreferredtoassignal generators.
Oscilloscope An instrumentthatdisplaysaplotof voltage over time. Oftenreferredtoasa scope.
Overload A load inexcessof the designlimitforacircuit.
Parallel circuit A circuitwithtwo or more loads(orsources) connectedsuchthatall have the same voltage butdifferent
currents. Each loadcan be operatedindependentof the others. Parallelsourcesshouldhave equal voltage ratings.
Period The time insecondsthatis requiredtocomplete one cycle of awaveform.
Permeability The abilityof a magneticmaterial toconductmagneticlinesof force.
Phase A time relationshipbetweentwoelectrical quantities.
Polarity For electrical charge,the indicationof acharge as eitherpositive(+) ornegative (-). Voltage ata pointwouldbe
indicatedasbeingeitherpositiveornegative withrespecttosome otherpoint. Formagneticpoles,the indicationaseither
north or south.
Positive For sources,impliesthe terminal thathasa deficiencyof free electrons. Also,canimplythe polarityof apointina
circuitin respecttosome otherpoint.
Potentiometer A three-terminalresistorwithanadjustable centerconnectiongenerallyusedtocontrol voltage;widelyused
for volume control inradioandtelevisionreceivers.Inthissense,alsocalleda Pot.
Power The rate at whichenergyisconsumed. Inelectronicsitreferstothe consumptionof electrical energyinjoulesover
time;measuredinwatts.
Power factor(PF) The ratioof true powerto the apparentpowerina circuit,especiallythosethatare not purelyresistive. It
isalso equal tothe cosine of the phase angle for the circuit.
Power supply Generally,adevice orcircuitusedto convertalternatingcurrent(ac) of specificvoltagetoone or more direct
current(dc) valuesof specificvoltage andcurrentratings. May have variable voltage abilityinsome instances. Mayalsorefer
to a device thatconvertsa specificdcvalue toanotherdc value (dcto dc converter).
Primary cell A device thatusesupitsingredientstoconvertchemical energytoelectrical energyandtherefore cannotbe
recharged.
Primary winding The inputwindingtoa transformer.
Printedcircuit (PC) board A fiberglassboardwithcopperfoil asthe conductorstointerconnectthe attachedelectrical
components.
Random-access memory(RAM) A read/write memorythatallowsdate storage (Write) anddataretrieval (Read) toany
locationinanyorder. Consideredtobe temporary(volatile) inthatthe contentsare lostif poweristurnedoff.
Reactance Oppositiontocurrentoffered bycapacitorsandinductorsinthe formof a counter-electromotiveforce (cemf),but
expressedinohms. Reactance doesnotconsume powerbutgivesthe appearance thatitdoes.
Read only memory(ROM) A classificationof non-volatile memorythathasitscontentsbuiltinattime of manufacturerand
whichcannotbe changedandcannot be lostif poweristurnedoff. VariationsincludeProgrammable (PROM) andErasable
Programmable (EPROM) whichhasprovisionsforuserprogramming.
Rectifier A solidstate device thatconvertsalternatingcurrenttopulseddirectcurrent.
Relay An electromechanicaldevice thatuseselectromagnetismtomechanicallyswitchelectrical circuits. The output
contacts are designedtobe eithernormallyopen(NO) ornormally closed(NC). Some relaysprovidebotharrangementsand
multiple switches.
Resistance (R) The oppositiontocurrentflowinacircuit; measuredinohms.
Resistor Anelectrical componentdesignedtoprovide aspecificresistance. Availableinmanyformatssuchas fixed,tapped,
and variable. See potentiometerandrheostat.
Resonance A circuit conditionwhenthe inductivereactance (XL) equalsthe capacitive reactance (XC). A resonantcircuit is
one that has beentunedtothat conditionand resonantfrequencyisthat frequencythatresonance occursina circuitand
providesamaximumoutputforone of its circuitvariables.
Rheostat A two-terminal resistorwithanadjustablecenterconnectionandone endconnectiongenerallyusedtocontrol
current.
Ripple The small amountof ac voltage thatstill remainsinthe outputof a dc powersupply.
RMS Root mean square The value of an ac sine wave thatindicatesitsequivalentdcvalue forproducingheat. Alsocalled
the effective value,itisequal to70.7% of the maximumvalue (peakvalue)forthe waveform.
Schematic or schematic diagram A drawingdipictinghow the componentsare connectedusingstandarizedsymbols.
Secondary cell A device whose ingredientsconvertchemical energytoelectricalenergybutcanbe recharged.
Secondary winding The outputwindingof atransformeror one of several outputwindings.
Seriescircuit A circuitarrangementof twoor more loads(orsources) connectedend-to-endonlyallowingforone current
path. Therefore,all componentshave the same currentbutcanhave differentvoltage. Anopenatany pointorin any
componentinterruptscurrentflow forall.
Semiconductor Any of varioussolidcrystalline substances,suchasgermaniumor silicon,havingelectrical conductivity
greaterthan insulatorsbutlessthangoodconductors. In electronicstheseare generallydopedtofromeitherN type orPtype
material. These materialsare the foundationalmaterial fordiodesandtransistors.
Short circuit Anundesirable low resistancepathbetweentwopointsinacircuit.
Siemen(S) The unitof measurementforconductance. NamedforErnstWernervon Siemens,aGerman engineerwho
made notable improvementstotelegraphicand electrical apparatus.
Silicon-controlledrectifier(SCR) See thyristor

5. Sine wave A waveformwhose instantanous amplitude isafunctionof the sine of the angle of rotationforthat instant. The
outputwaveformproducedbyrotatingaloopin a magneticfield,andthe outputof anoscillatorgeneratingapure frequency.
Solar cell A device thatconvertslight energytoelectrical energy.Alsocalleda photovoltaiccell.
Solder Anyof variousfusible alloys,usuallytinandlead,usedtojoinmetallicparts.Inelectronicsusedtoconnect
componentstoPCboards or to aidthe conductivityandmechanical junctionsof connectionsandsplices.
Solenoid Electromechanical device thatuse electromagnetismtoproduce amechanical operation.
Solid-state The term that describescomponentsorcircuitsthatuse semiconductorstechnology.
Source General termto describe devicesthatprovideselectricalenergyattheiroutputterminalstooperate acircuit.
Examples:battery,solarcell,generatorandalternator,orpowersupply.
Static electricity A stationaryelectrical charge onanobject.
Stator The electromagneticpartof a motor or generatorthatdoesnot rotate.
Steppermotor A motor type drivenwithdigital codesthatmovesindiscrete angularincrementswitheachcode change.
Superpositiontheorem A methodforanalyzingacomplex networkof bilateral(conductsequallywellinbothdirections)
componentshavingmultiplesources.
Surge A veryrapidincrease of currentor voltage.
Switch A device usedtoopen(turnoff) andclose (turnon) electrical circuitsthatcan be designed tooperatedbynumerous
actionssuch as toggle,slide,andpushbuttonactions.Standardconfigurationsinclude SPST,SPDT,DPST,andDPDT.
Terminal A connectionpointforelectrical componentsorconductors.
Thermistor A resistormade of semiconductormaterial havingresistance thatvariesrapidlyandpredictablywith
temperature. Usedasa temperature sensor,the resistance variesinverselywithtemperature.
Thermocouple A thermoelectricdevice usedtomeasure temperaturesaccurately,consist of twodissimilarmetalsjoinedso
that a potential difference isgeneratedthatisrepresentative of the temperature of the junction.
Thevenin’stheorem A methodof reducinga complex networkof bilateral (conductsequallywell inbothdirections)
componentstoone voltage source andone resistorinserieswiththe loadterminals.
Thyristor A broad classificationof semiconductordevicesusedaselectronicswitches. Examplesinclude diacs,SCRs,and
triacs.
Tolerance Usedto describe the allowable varianceinameasurementora componentsvalue.
Transducer A device usedtoconvertinputenergyof one formintooutputenergyof another.
Transformer A device usedtotransferelectricenergyfromone circuittoanother,especiallyapairof multiplywound,
inductivelycoupledwire coilsthateffectsucha transferwithachange involtage,current,phase,orotherelectric
characteristic.Generallyusedtoconvertone voltage-currentrelationshiptoanother. Step-uptransformer,increasethe
voltage while decreasingthe current,and step-downtransformerdecrease the voltage while increasingthe current.
Transistor A small electronicsemiconductordevice havingatleastthree electrical contacts,usedinacircuitas an amplifier
or a switch.See:BJT,JFET,MOSFET.
True power The actual powerconsumedbya circuit;measuredinwatts.
Volt (V) The unitby whichan electromotive force orvoltage ismeasured.Namedfor AlessandroVolta,the Italianphysicist
whoinventedthe first electricbattery(1800).
Voltage (V) Same as emf. The force or electrical pressurethathasthe potential tocause electronflow inacircuit.
Voltage divider A seriescircuitthatdividesvoltage.
Voltage drop The difference inpotentialbetweentwopointscausedbycurrentflow throughacomponent.
Voltmeter Aninstrumentusedtomeasure voltage.
Watt (W) The unitof measurementforpower. One wattequalstothe workdone whenone joule isusedpersecond.
NamedforJames Watt the Britishengineerandinventor.
Watt-hour(Wh) Unit of energyconsumedatthe rate of one watt(W) fora time of one hour. Equivalentto3,600 joules.
Wheatstone Bridge An instrumentora circuitconsistingof fourresistorsortheirequivalentinaseries-parallel
arrangement,usedtodeterminethe value of anunknownresistance whenthe otherthree resistancesare known.
Wiringdiagram A graphic representationof howcircuitcomponentsare connected.
ZenerDiode A semiconductordevice designedtooperate ata fixedvoltage asavoltage regulator.