Electricity & Electronics Merit Badge · Types of Electricity Direct Current (DC) Type of...
Transcript of Electricity & Electronics Merit Badge · Types of Electricity Direct Current (DC) Type of...
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Electricity&Electronics
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TypesofElectricitySta>cElectricitySta>celectricityisusuallycreatedwhenmaterialsarepulledapartorrubbedtogether,causingposi>ve(+)chargestocollectononematerialandnega>ve(−)chargesontheothersurface..Sparksmayresult!
Examplesofoccurrenceofsta>celectricity:
1. Lightning.2. Combinghair.3. Walkingacrosscarpetand
geUngshocked.4. Pullingoutscotchtape.ElectricityMeritBadgeClass1
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TypesofElectricityDirectCurrent(DC)Typeofelectricityusedinmost,ifnotallelectronicswehavetoday.Currentonlyflowsinonedirec>on(notbothdirec>ons,likeAC).
ExamplesofDCusage:
1. MP3players2. Radios3. Electricityincars.4. Anywhereyouuseaba\eryfor
power.
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TypesofElectricityAlterna>ngCurrent(AC)Thecommonformofelectricityfrompowerplanttohome/office.Itsdirec>onisreversed60>mespersecondintheU.S.;50>mesinEurope.
ExamplesofACusage:
1. Kitchens:Stoves,ovens,mixer,etc.
2. Computerchargers3. Lightsinhouse4. Homeaircondi>oners.
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Voltage• Voltsistheelectromo>veforcethatcauses electrons(current)toflow.• Voltagecanalsobethoughtofastheelectrical
forcethatpusheselectronsinawire.• UnitsforvoltageisVOLTS.• ThesymbolforvoltageisE.• Theschema>csymbolfordcvoltageisgenerallyshownasaba\ery
GND
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Voltage–WaterAnalogy
1. Gravityprovidestheforceforwater(current)toflow.
2. Thisillustratesasmallvoltage,socurrentflowissmall.
3. Youcanincreasewater(current)flowbymakingthepipelargeraswell.
1. Gravityprovidestheforceforwater(current)toflow.
2. Thisillustratesalargervoltage,socurrentflowislarger.
3. Youcanincreasewater(current)flowbymakingthepipelargeraswell.
Smallheight=lowvoltage Bigheight=highvoltage
height
height
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Current
• Current:Definedas“flow(>merateofchange)ofelectrons”.
• Current: UnitsofcurrentisAMPS.• Current:ElectricalsymbolforcurrentisI(eye).
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CurrentFlow–WaterAnalogy
1. Waterflowsinthehose,enteringatthetopandexi>ngthebo\om.
2. Thewateristhe“current”;theflowofelectrons.3. Themorewaterflowinginthepipe,themorecurrent
isflowinginthewire.4. Differentpipediametersillustratesdifferent
resistancetowaterflow,whichcorrelatestodifferentresistorvalues.
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Resistance
• Resistanceistheelectricalpropertyofa
substancetoresisttheflowofelectrons.• TheunitsofresistanceisOHMS(Ω).• ThesymbolforresistanceisR.• Theschema>csymbolis• Thelargertheresistance,themoreresistance
tocurrentflow.
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Resistance–WaterAnalogy
• Differentpipediametersrepresentsdifferentresistorvalues.
• Thesmallerthediameterofthepipe,thelargertheresistance.
1Ω
10Ω
100Ω
1000Ω
10000Ω
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ElectricalTerms• Circuit-Aconductororsystempathofelectricalelementsthroughwhichcurrentwillflow.
• Poten>alDifference-TheVoltagebetweentwopointsinacircuit.
• Impedance-ThetermusedinACCircuitsfortheresistancetotheflowofcurrent.
• ShortCircuit-Anabnormalconnec>onoflowimpedance(resistance)betweentwopointsofdifferentpoten>al.
• Ground-Apointofcommonconnec>onofzerovoltsorentheearth
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OtherElectricalTerms
• Wa\-Powertodoworkat1joule/secorW=VxI
• Rec>fier-ElectronicorMechanicalmeanstoconvertACtoDC.
• Rheostat-Anadjustableresistancesuchthatresistancecanbechangedwithoutbreakingthecircuit(examplelightdimmer).
• Conductor-Materialthatwillallowcurrenttopasscon>nuouslyalongit(wire).
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OtherElectricalTerms
• Switch-ElectronicorMechanicalmeansforopeningandclosingacircuit.
• Fuse-Adevicethatprotectsacircuitfromover-currentbymel>ngalinkinthedevice.
• CircuitBreaker-Adevicethatprotectsacircuitforover-currentbyopeningthecircuitwithaswitch.
• Cycle-Onecompletereversalofalterna>ngcurrentorvoltage.
• Hertz-Onecyclepersecond
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EquipmentUsedToMeasureElectricalQuan>>esandQuali>es
Volt/Ohm/AmpMeterUsuallyreferredtoasamul>-meter.WiththiswecanmeasurecurrentA,voltageVandresistanceR.
OscilloscopeUsuallyreferredtoasaScopeorO-ScopeWiththiswecan‘see’voltagewaveforms.Thisisveryusefulwhenvoltageischanging,asameterisnogoodtouswhenthisishappening.
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OhmsLawDCCircuitsVolts=CurrentxResistance
• E=IxR • Units– EisinVolts– ItheelectricalcurrentisinAmps– RisResistanceisinOhmsExample:IftheVoltageEstaystheSAMEandResistanceRgoesUP,thentheamountofCurrentIflowinginthecircuitgoesDOWN
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ElectricityandElectronicSymbols
SinglePole,DoubleThrowSwitch(SPDT)
Ba\ery
Resistor
LightEmiUngDiode(LED)
Buzzer
Fuse
Lamp
or
Capacitor
Ground
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CIRCUITDIAGRAM(SCHEMATIC)
+
SWITCHLAMP10Ohms
GROUNDGROUND
FLASHLIGHT
TWOGROUNDSYMBOLSISTHESAMEASCONNECTINGWITHAWIRE
GROUND=0VOLTS
V=9V I
V=IxRV=9VoltsR=10OhmsI=?Amps9V=IAx10Ohms9V/10Ohms=IAmps0.9Amps=I
CalculateI
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ElectricitySafety• HighVoltage(120VACorgreater)–Safetymainlyaboutnottouchingthewrongthing.
• Currentkills–Only60voltscankillwhencurrentflowsthroughheartorheadforasufficientlengthof>me.
• Ventricularfibrilla>on-Currentpassingthroughheartcausesknocksheartoutofsynchroniza>on.
• Iftheshockdoesn’tkillyou,youcans>llbebadlyburnedfromtouchingthewrongthing.
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ElectricShock
• Ifapersonisincontactwithanenergized(live)circuitdonottouchthem.– Turnoffthebreaker.– Ifyoudonotknowwherethebreakerislocatedpushthecircuitoffofthepersonwithadryobjectlikeabroom,mophandleorwoodenchair.
– Donotuseanyobjectthatismetalorwet.– Waterlikemetalcanconductelectricityinamountsthatcanbedangerous.
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RemovalofLiveWire
• Ifyoucannotremovethewirewithadryobjectorturnoffthebreakerthen:– Besureyouareonadrysurfaceand– Findadryshirt,sheetorsweaterandloopitaroundthewireandpullitoff
– Orincaseyoucannotgettothewiretrythesamemethodtopullthepersonoffthewire.
– Onceyouhaveapersonawayfromthewireschecktoseeiftheyneedar>ficialrespira>on.
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HighPowerLines
• Ifapersonisincontactwithhighpowerlines:– Donottouchthem.– Stayatleast20feetawayascurrentcanflowthroughtheground.
– Call911.– Letthefireandpolicemanagethesitua>on.
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PowerLines
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Trea>ngElectricalBurns
• Whenapersonhasasevereelectricalburn:– Donotapplyice,ointment,water,medica>on,bandagesordressings
– Donottouchorbreakboilsorblisters– Donota\empttoremoveclothing
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ElectricalStorms• About54peoplearekilledfromlightningeveryyearandseveralhundredareinjured.
• Numerousforestandhousefiresarestartedbylightning.
• Ifoutdoorsavoidtallsolitarytrees,towers,water,mountaintopsandridgecrests,metalfencesandanyobjectlikeametaltentpole.
• Thesafestplaceisadenseforestinalowlyingarea.
• Ifcaughtintheopenstaylow,spreadout,crouchwithbothfeettogetherandsolesontheground
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ElectricalFires• Theyaredifferentfromotherfiresinthattryingtoputoutafire:– Neverusewater.– Call911.– Turnoffmainbreaker– Useonlyex>nguishersratedforfires.ClassCfiresinvolveelectricalequipment,suchasappliances,wiring,circuitbreakersandoutlets.Neverusewater-theriskofelectricalshockisfartoogreat!TheCclassifica>onmeanstheex>nguishingagentisnon-conduc>ve.Geometricsymbol(bluecircle)
– Iffiredoesnotgooutleavethebuilding.
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PersonalSafety• Beawareofwhatyouaredoing,andwhereyouareplacingequipmentandyourselfinanelectricalcircuit.
• Paya\en>ontoenergizedcircuits–Isthepoweron?Makesuretheelectricityisturnedoffespeciallywhenworkingon120VACorhigherelectricalcircuits.
• Paya\en>ontohotsolderingirons.Keepagooddistancebetweenyouthosenexttoyou.
• Knowwhenyouareworkingwithhighcurrentand/orhighvoltagecircuits.
• THINKbeforeyoudosomething.• Wearsafetyglasseswhensoldering.
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Howtoavoidshock.• Turnpoweroffbeforeworkingonequipment.• Don’ttouchcircuitsthatcouldhavehighvoltageonthem.• Donotallowcurrenttoflowthroughheart(ormaybe
mouth,inthiscaseofanelectrifiedfence).
SampleHomeElectricalInspec>onChecklist
• Outlets• χCheckforoutletsthathaveloose-fiUngplugs,whichcanoverheatandleadtofire.• χReplaceanymissingorbrokenwallplates.• χMakesuretherearesafetycoversonallunusedoutletsthatareaccessibletochildren.• LineCords• χMakesurecordsareingoodcondi>on-notfrayedorcracked.• χMakesuretheyareplacedoutoftrafficareas.• χMakesurethatcordsarenotnailedorstapledtothewall,baseboardortoanotherobject.• χMakesurethatcordsarenotundercarpetsorrugsoranyfurniturerestsonthem.• ExtensionCords• χChecktoseethatextensioncordsarenotoverloaded&onlybeusedonatemporarybasis,notaspermanentwiring.• χMakesureextensioncordshavesafetyclosurestohelpprotectchildrenfromshockhazardsandmouthburns.• Plugs• χMakesureyourplugsfitsecurelyintoyouroutlets.• χMakesurenoplugshavehadthegroundpin(thethirdprong)removedinordertomakeathree-prongfitatwo-conductor• outlet;thiscouldleadtoanelectricalshock.• χNeverforceaplugintoanoutletifitdoesn'tfit.• χAvoidoverloadingoutletswithtoomanyappliances.• GroundFaultCircuitInterrupters(GFCIs)• GFCIscanhelppreventelectrocu>on.WhenaGFCIsensescurrentleakageinanelectricalcircuit,itassumesagroundfaulthas• occurred.Ittheninterruptspowerfastenoughtohelppreventseriousinjuryfromelectricalshock.GFCIscanbeinstalledatthe• outlet,orasareplacementforthecircuitbreakerforanen>recircuitatthefusebox.• χKitchenχBathroomsχGarageχLaundryroomχOutdoors• χTestGFCIsaccordingtothemanufacturer'sinstruc>onsmonthlyandarermajorelectricalstormstomakesuretheyare• workingproperly.
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SampleHomeElectricalInspec>onChecklist
• LightBulbs• χCheckthewa\ageofallbulbsinlightfixturestomakesuretheyarethecorrectwa\ageforthesizeofthefixture.• χReplacebulbsthathavehigherwa\agethanrecommended;ifyoudon'tknowthecorrectwa\age,checkwiththe• manufacturerofthefixture.• χMakesurebulbsarescrewedinsecurely;loosebulbsmayoverheat.• CircuitBreakers/Fuses• χMakesurecircuitbreakersandfusesarethecorrectsizecurrentra>ngfortheircircuit.Ifyoudonotknowthecorrectsize,• haveanelectricianiden>fyandlabelthesizetobeused.Alwaysreplaceafusewiththecorrectlyspecifiedsizefuse.• χMakesureeveryoneinyourhomeknowswherethemainbreakerislocatedandhowtoshutofpowertotheen>rehouse.• PlugInAppliances• χMakesuretherearenoplugged-inapplianceswheretheymightfallincontactwithwater.Ifaplugged-inappliancefallsinto• water,NEVERreachintopullitout—evenifit'sturnedoff.Firstturnoffthepowersourceatthepanelboardandthen• unplugtheappliance.Ifyouhaveanappliancethathasgo\enwet,don'tuseitun>lithasbeencheckedbyaqualifiedrepair• person.• Appliances• χIfanappliancerepeatedlyblowsafuse,tripsacircuitbreakerorifithasgivenyouashock,unplugitandhaveitrepairedor• replaced.• Entertainment/ComputerEquipment• χChecktoseethattheequipmentisingoodcondi>onandworkingproperly.Lookforcracksordamageinwiring,plugsand• connectors.• χUseasurgeprotectorbearingthesealofana>onallyrecognizedcer>fica>onagency.
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• OutdoorSafety• χElectric-poweredmowersandotherelectrictoolsshouldnotbeusedintherain,onwetgrassorinwetcondi>ons.• χInspectpowertools&electriclawnmowersbeforeeachuseforfrayedpowercords,brokenplugs&crackedorbroken• housings.Ifanypartisdamaged,stopusingitimmediately.Repairitorreplaceit.• χAlwaysuseanextensioncordmarkedforoutdooruseandratedforthepowerneedsofyourtools.• χRemembertounplugallportablepowertoolswhennotinuse.• χWhenusingladders,watchoutforoverheadwiresandpowerlines.Stayatleast10feetfromalloverheadlines.• Lightning• χDuringanelectricalstorm,donotuseappliances(i.e.,hairdryers,toastersandradios)ortelephones(exceptinan• emergency);donottakeabathorshower;• χKeepba\eriesonhandforflashlightsandradiosincaseofapoweroutage.• χUsesurgeprotectorsonelectronicdevices,appliances,phones,faxmachinesandmodems.• SpaceHeaters• χSpaceheatersaremeanttosupplysupplementalheat.Keepspaceheatersatleast3r.awayfromanycombus>ble• materialssuchasbedding,clothing,draperies,furnitureandrugs.• χDon'tusespaceheatersinroomswherechildrenareunsupervisedandremembertoturnoffandunplugwhennotinuse.• χDonotusespaceheaterswithextensioncords;plugdirectlyintoanoutletonarela>velyunburdenedcircuit.• HalogenFloorLamps• χHalogenfloorlampsoperateatmuchhighertemperaturesthanastandardincandescentlightbulb.Neverplaceahalogen• floorlampwhereitcouldcomeincontactwithdraperies,clothingorothercombus>blematerials.• χBesuretoturnthelampoffwheneveryouleavetheroomforanextendedperiodof>me.• χNeverusetorchierelampsinchildren'sbedroomsorplayrooms.Considerusingcoolerfluorescentfloorlamps.
SampleHomeElectricalInspec>onChecklist
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Howcanwesaveenergyinourhomes,schoolsandscoutareas
• Turnoffunneededorunusedlights• Unplugchargerswhennotinusecharging• Whenappliancesneedtobereplacedbuyenergystarappliances
• Inthesummersettheindoortemperatureadegreeortwohigherandinwinteradegreeortwolower
• TurnofftheTVwhenleavingtheroom6/13/17 ElectricityMeritBadgeClass1
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Howcanwesaveenergyinourhomes,schoolsandscoutareas
• Plantripstothestoresothatonetripcancompleteseveralerrands
• Don’texceedthespeedlimit• Useabikeforshorttripsratherthanacar• Makesurethatthebuildinghasadequateinsula>on
• Stopallairleaksinabuildinguseinfraredscannertofindleaks
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Howcanwesaveenergyinourhomes,schoolsandscoutareas
• Cleanorreplaceairfiltersregularly• Useenergyefficientlightbulbs• Keepthedoorsclosedwhencoolingorhea>ng• Shadeyourwindowsinthesummer• Useceilingfans• Closeallfireplaceflueswhennotinuse• Washonlyfullloads• Setwashersoneconomyloadtosavewater
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Howcanwesaveenergyinourhomes,schoolsandscoutareas
• Setwatertemperaturelower• Takeshortershowers• Don’tletthewaterrunwhilebrushingorshaving
• LookforenergyefficientcomputersandTVs• Unplugunusedappliancesanddevicesastheyusepoweratall>mes
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