better hope – brighter future

AQAENERGY–part1

EnergyCon

servationan

dDissipation

Energystoresand

changes

System Anobject orgroupofobjectsthatinteracttogether EG:Kettleboiling water.

Energy storesKinetic,chemical,internal(thermal),

gravitationalpotential, elasticpotential,magnetic,electrostatic,nuclear

Energyisgainedorlostfromtheobjectordevice.

Waystotransferenergy

Light,sound,electricity,thermal,kineticarewaystotransferfromonestoreto

anotherstoreofenergy.

EG: electricalenergytransferschemicalenergyintothermalenergytoheatwaterup.Unit Joules(J)

Efficiency=UsefuloutputenergytransferTotalinputenergytransfer

Efficiency=UsefulpoweroutputTotalpowerinput

HIGHER:efficiencycanbeincreasedusingmachines.

Prefix Multiple Standardform

Kilo 1000 103

Mega 1000000 106

Giga 100000000 109

Units

SpecificHeatCapacity JoulesperKilogramdegreeCelsius(J/Kg°C)

Temperaturechange DegreesCelsius( °C)

Workdone Joules(J)

Force Newton(N)

Distancemoved Metre (m)

Power Watts(W)

Time Seconds(s)

Kineticenergy

Energy storedbyamovingobject

½XmassX(speed)2½mv2

ElasticPotentialenergy

Energystoredinastretchedspring,elasticband

½ XspringconstantX(extension)2½ke2

(Assumingthelimitofproportionalityhasnotbeenexceeded)

GravitationalPotentialenergy

Energygainedbyanobjectraisedabovetheground

MassXgravitationalfieldstrengthXheightmgh

Dissipate

Toscatterinalldirectionsortousewastefully

Whenenergy is‘wasted’,itdissipatesintothe

surroundingsasinternal(thermal)energy.

Work

Doingworktransfersenergyfromonestoreto

another

Byapplyingaforcetomoveanobjecttheenergystoreischanged.

Workdone=ForceXdistancemovedW=Fs

Power Therateofenergytransfer

1 Jouleofenergypersecond =1wattofpower

Power=energytransfer÷ timeP=E÷ t

Power=workdone÷ time,P=W÷ t

Energy

pathwaysMechanical Forceactsuponanobject

Electrical Electriccurrentflow

Heat Temperaturedifferencebetween objects

Radiation Electromagneticwaves orsound

Efficiency Howmuchenergyisusefullytransferred

Changeinthermalenergy=massXspecificheatcapacityX temperaturechange ∆E=mXc X ∆θ

SpecificHeat

Capacity

Energyneededtoraise1kgof

substanceby1°C

Dependson:massofsubstance,whatthesubstanceis andenergyputintothesystem.

Principleofconservationofenergy

Theamountofenergy

alwaysstaysthesame.

Energycannotbecreatedordestroyed,onlychangedfromonestoretoanother.

Units

Energy(KE,EPE,GPE,thermal) Joules(J)

Velocity Metrespersecond(m/s)

Springconstant Newtonpermetre(N/m)

Extension Metres(m)

Mass Kilogram(Kg)

Gravitationalfieldstrength Newtonperkilogram(N/Kg)

Height Metres(m)

Reducingfriction- usingwheels,applyinglubrication.Reducingairresistance–

travellingslowly,streamlining.

Frictionalforcescauseenergytobetransferredasthermalenergy.Thisis

wasted.

HIGHER:Whenanobjectismoved,

energyistransferredbydoingwork.

Closedsystem

Nochangeintotalenergyin

system

Opensystem

Energycandissipate

Usefulenergy

Energytransferredandused

Wastedenergy

Dissipatedenergy,storedlessusefully

Workdone=ForceXdistancemoved

Waystoreduce‘wasted’energy

Energytransferredusefully

Insulation,streamlinedesign,lubricationofmovingparts.

better hope – brighter future

AQAENERGY–part2

Non-renewableenergyresource

Thesewillrunout.Itisafinite reserve.Itcannotbe

replenished.

e.g.Fossilfuels (coal,oilandgas)andnuclearfuels.

Renewableenergyresource

Thesewillneverrunout.Itisaninfinite reserve.Itcanbereplenished.

e.g.Solar,Tides,Waves,Wind,Geothermal,Biomass,Hydroelectric

Powerstation– NB:Youneedtounderstandtheprinciplebehindgeneratingelectricity.Anenergyresourceisburnttomakesteamtodriveaturbinewhichdrivesthegenerator.

NationalGrid

GlobalEnergy

Resources

Energyresource Howitworks Uses Positive Negative

FossilFuels(coal, oiland

gas)

Burnt toreleasethermalenergyusedtoturnwaterintosteamtoturn

turbines

Generatingelectricity,heatingandtransport

Provides mostoftheUKenergy.Largereserves.Cheaptoextract.Usedintransport,heatingand

makingelectricity.Easytotransport.

Non-renewable. Burningcoalandoilreleasessulfur dioxide.Whenmixedwithrainmakesacidrain.Acidraindamagesbuildingandkills

plants.Burningfossilfuels releasescarbondioxidewhichcontributestoglobalwarming.Seriousenvironmentaldamageifoilspilt.

Nuclear Nuclearfissionprocess GeneratingelectricityNo greenhousegasesproduced.

Lotsofenergyproducedfromsmallamountsoffuel.

Non-renewable.Dangersofradioactive materialsbeingreleasedintoairorwater.Nuclearsitesneedhighlevelsofsecurity.Startupcostsanddecommissioncostsveryexpensive.Toxicwasteneedscarefulstoring.

Biofuel Plant matterburnttoreleasethermalenergy

Transportandgeneratingelectricity

Renewable.Asplantsgrow,theyremovecarbondioxide.Theyare

‘carbonneutral’.

Large areasoflandneededtogrowfuelcrops.Habitatsdestroyedandfoodnotgrown.Emits carbondioxidewhenburntthusaddingto

greenhousegasesandglobalwarming.

TidesEverydaytidesriseandfall,sogenerationofelectricitycanbe

predictedGeneratingelectricity

Renewable.Predictabledue toconsistencyoftides.No

greenhousegasesproduced.

Expensivetosetup.Adamlikestructureisbuiltacrossanestuary,alteringhabitatsandcausingproblemsforshipsandboats.

Waves Upanddownmotionturnsturbines Generatingelectricity Renewable.Nowasteproducts. Canbeunreliabledependsonwaveoutputaslargewavescanstopthepistonsworking.

Hydroelectric Fallingwaterspinsaturbine Generatingelectricity Renewable.Nowasteproducts. Habitatsdestroyed whendamisbuilt.

Wind Movementcausesturbine tospinwhichturnsagenerator Generatingelectricity Renewable.Nowasteproducts. Unreliable– wind varies.Visualandnoisepollution.Dangerousto

migratingbirds.

SolarDirectlyheatsobjectsinsolarpanelsorsunlightcaptured inphotovoltaic

cells

Generatingelectricityandsomeheating Renewable.Nowasteproducts. Makingandinstallingsolarpanelsexpensive. Unreliableduetolight

intensity.

GeothermalHotrocksunderthe groundheatswatertoproducesteamtoturn

turbine

Generatingelectricityandheating

Renewable.Clean.Nogreenhousegasesproduced.

Limitedtoasmallnumberofcountries.Geothermal powerstationscancauseearthquaketremors.

Transport Petrol,diesel,keroseneproducedfromoil

Usedincars,trainsandplanes.

Heating Gasandelectricity Usedinbuildings.

Electricity Mostgeneratedbyfossilfuels

Usedtopowermostdevices.

Usingfuels

Energyresources

Powerstation

Generateselectricity

Fuelburntreleasing

thermalenergy

Waterboilsintosteam

Steam turnsturbine

Turbineturnsgenerator

Generatorinducesvoltage

NationalGrid

Transportselectricity across

UKPowerstation Step-up

transformer Pylons Step-downtransformer

House,factory

Energydemandisincreasingas

populationincreases.

Renewableenergymakesupabout20%ofenergyconsumption.

Fossilfuelreservesarerunningout.

Usingrenewableenergywillneedtoincreasetomeetdemand.

better hope – brighter future

AQAElectricity

Circuitsymbols

Serie

sand

parallel

circuits

Cell Battery Switch Lamp Ammeter Voltmeter

Storeofchemicalenergy

Two ormorecellsinseries

Breakscircuit,turning

currentoff

Lightswhencurrentflows

Measurescurrent

Measurespotentialdifference

Current,potentialdifferenceandresistance

Energytransfers

Domesticusesandsafety

Staticelectricity

Current Flowofelectricalcharge

Ampere(A)

Potentialdifference(p.d.)

Howmuchelectricalworkis donebyacell Volts (V)

Charge Amountofelectricitytravelling inacircuit

Coulombs(C)

Diode LED LDR Fuse Resistor Variableresistor Thermistor

Currentflowsoneway

Emitslightwhencurrentflows

Resistancelowin

brightlight

Meltswhen

currentistoohigh

Affectsthesizeofcurrentflowing

Allowscurrenttobevaried

Resistancelowathigh

temp

3pinplug

Live- Brown Carriesp.d frommainssupply.

p.d betweenliveandearth=230V

Neutral- Blue Completesthecircuit. p.d.= OV

Earth– GreenandYellowstripes

Onlycarriescurrent ifthereisafault. p.d.=0V

Seriescircuit

Currentisthesameinallcomponents.

Totalp.d.frombatteryissharedbetweenallthecomponents.

Totalresistanceisthesumofeachcomponent’sresistance.

Parallelcircuit

Total currentisthesumof

eachcomponent’s

current.

p.d.acrossallcomponentsisthesame.

Totalresistanceislessthanthe

resistancevalueofthesmallest

individualresistor.

Electron

scarrycurrent.

Electron

sarefreeto

moveinm

etal.

‘Earthing’asafetydevice;Earthwirejoinsthemetalcase.

Charge=CurrentXtime Q=IXt

Series Parallel

Acircuitwithoneloop

Acircuitwithtwoormoreloops

Changing

curren

t Change thep.d.ofthecells

Addmorecomponents

Ammeter Setupinserieswithcomponents

Voltmeter Setupparallel tocomponents

Resistance(Ω)

A measurementofhowmuchcurrentflowisreduced

Thehighertheresistance, themoredifficultitisforcurrenttoflow.

Increasingresistance, reducescurrent.

Increasingvoltage, increasescurrent.

Resistance=Potentialdifference

÷ Current

R=V÷ I

Ohmicconduct

or

Ataconstant temperature,currentisdirectly

proportionaltothep.d.acrosstheresistor.

Filamentlamp

Ascurrentincreases,theresistanceincreases. Thetemperatureincreasesas

currentflows.

DiodeCurrentflowswhenp.d.flowsforward.Veryhighresistanceinreverse.

Current–Potential

differencegraphs

Controllingcurrent

CurrentandCharge

Alternatingcurrent Directcurrent

p.d.switchesdirectionmanytimesasecond,currentswitchesdirection

p.d.remainsinonedirection,

currentflowsthesamedirection

Generator. Cellorbattery.

Thermistor LDR

Resistancevarieswithtemperature

Resistancevarieswithlightintensity

Resistancedecreasesastemperature increases.

Resistancedecreasesaslight increases.

Totalp.d Ifcells arejoinedin

series,addupindividualcellvalues

PHYSICSonly

Power(W)=potentialdifferenceXcurrent R=VXI

P=I2 XRPower=(current)2 XresistanceWorkisdonewhenchargeflowing.

Energytransferred=PowerXtime E=PXt

National

Grid

Distributes electricitygeneratedinpowerstationsaroundUK

Step-up transformers Step-downtransformers

Increasevoltage,decreasecurrent

Decreasevoltage,increasecurrent

Increasesefficiency,reducesheatloss.

Makessaferforhouses.

Static

electricity Electrical

chargeisstationary

When twoinsulatingmaterialarerubbedtogether,electronsmovefromonematerialtotheother.Mainssupply

Frequency50Hz,230V

Likecharges Repel

Unlikecharges Attract

Shocks

Walkingoncarpetcausesfriction.Electronsmovetothepersonandchargebuildsup.Whenthepersontouchesametalobject,theelectronsconductaway,makingaspark.

Electricfields Charged objectscreateelectricfields

aroundthem.Strongestclosesttotheobject.Thefielddirectionisthedirectionofforceonapositivecharge.Addmorechargeincreasesfieldstrength.

better hope – brighter future

AQAPARTICLEMODEL

OFMATTER

Pressure

Changeofstate

Internalenergyandenergytransfers

Density=mass÷ volume.

State Particlearrangement Properties

SolidPackedinaregular

structure.Strongforcesholdinplacesocannotmove.

Difficulttochangeshape.

Liquid Closetogether,forceskeepcontactbut canmoveabout.

Canchangeshapebutdifficulttocompress.

Gas

Separatedbylargedistances.Weakforcesso

constantlyrandomlymoving.

Canexpandtofillaspace,easytocompress.

Particlemodel

Changeinthermalenergy=massXspecificheatcapacityXtemperaturechange.

Energyneeded=massX specificlatentheat.

P =m÷ V

Units

Density Kilogramspermetrecubed(kg/m3)

Mass Kilograms (kg)

Volume Metrescubed(m3)

Energyneeded Joules(J)

Specificlatentheat Jouleperkilogram(J/kg)

Changeinthermalenergy Joules(J)

Specificheatcapacity JouleperkilogramdegreesCelsius(J/kg°C)

Temperaturechange DegreesCelsius( °C)

Pressure Pascals (Pa)

∆E=mXc X ∆θ

Kinetictheoryofgases

Gasparticlesareinaconstantstateofrandommotion.

Nokineticenergyislostwhengasparticlescollidewitheachotheror

thecontainer.

Temperatureofgasislinkedtotheaveragekineticenergyofthe

particles.

Ifkineticenergyincreasessodoesthetemperatureofgas.

Pressureofafixedvolumeofgasincreasesastemperatureincreases(temperatureincreases,speedincreases,collisionsoccurmorefrequentlyandwithmoreforceso

pressureincreases).

PV=constant.

Freezing Liquidturnstoasolid.Internalenergydecreases.

Melting Solidturnstoaliquid.Internalenergyincreases.

Boiling/Evaporating

Liquidturnstoagas.Internalenergyincreases.

Condensation Gasturnstoaliquid.Internalenergydecreases.

Sublimation Solidturnsdirectlyintoagas.Internalenergyincreases.

Conservationofmass

Whensubstanceschangestate,massisconserved.

Physicalchange

Nonew substanceismade,processcanbereversed.

SpecificLatentHeat

Energyneededtochange1kgof asubstance’sstate

SpecificLatentHeatofFusion

Energyneededtochange1kgofsolidinto1kgofliquidatthesametemperature

SpecificLatentHeatof

Vaporisation

Energyneededtochange1kgofliquidinto1kgofgasatthesametemperature

Internalene

rgy

Energystoredinsideasystembyparticles

Internalenergyisthetotalkineticandpotentialenergyofalltheparticles(atomsand

molecules)inasystem.

Heatingchangestheenergystored

withinasystem

Heatingcausesachangeinstate.Asparticlesseparate,potentialenergystoredincreases.

Heatingincreasesthetemperatureofasystem.Particlesmovefastersokineticenergyof

particlesincreases.

∆E=mXL

Density Massofasubstanceinagivenvolume

PHYSICS ONLY: whenyoudoworkthetemperatureincreases e.g. pumpairquicklyintoaball,theairgetshotbecauseasthepistoninthepumpmovestheparticlesbounceoffincreasingkineticenergy, whichcausesa temperaturerise.

Reducingthevolumeofafixedmassofgas

increasesthepressure.

Halvingthevolumedoublesthepressure.

SpecificHeat

Capacity

Energyneededtoraise1kgofsubstanceby

1°C

Dependson:• Massofsubstance• Whatthesubstanceis• Energyputintothe

system.

P1V1 =P2V2

better hope – brighter futureAtom

structure

AQAATOMIC

STRUCTURE

Nuclearfissionan

dfusio

n

AtomsandNuclearRadiation

AtomsandIsotopes

PHYSICSONLY:HazardsandusesofRadioactive

emissionsandofbackgroundradiation

Particle Charge Size Found

Neutron None 1Inthenucleus

Proton + 1

Electron - Tiny Orbitsthenucleus

Atom Samenumberofprotonsandelectrons

Ion Unequalnumberofelectronstoprotons

Massnumber Numberofprotonsand neutrons

Atomicnumber Numberofprotons

Negativeion PositiveionElectronsgained Electronslost

Democritus Suggestedideaofatomsas smallspheresthatcannotbecut.

JJThomson(1897)

Discoveredelectrons– emittedfromsurfaceofhotmetal.Showedelectronsarenegativelychargedand

thattheyare muchlessmassivethanatoms.

Thomson(1904)

Proposed‘plumpudding’ model – atomsareaballofpositivechargewithnegativeelectronsembeddedinit.

GeigerandMarsden(1909)

Directedbeamofalpha particles(He2+)atathinsheetofgoldfoil.Foundsometravelledthrough,somewere

deflected,somebouncedback.

Rutherford(1911)

Usedaboveevidencetosuggestalphaparticlesdeflected duetoelectrostaticinteractionbetweentheverysmallchargednucleus,nucleuswasmassive.Proposedmassandpositivechargecontainedinnucleuswhileelectronsfoundoutsidethenucleus

whichcancelthepositivechargeexactly.

Bohr(1913)

Suggestedmodernmodelofatom– electronsincircularorbitsaroundnucleus, electronscanchangeorbitsbyemittingorabsorbingelectromagnetic

radiation.Hisresearchledtotheideaofsomeparticleswithinthenucleushavingpositivecharge;thesewere

namedprotons.

Chadwick(1932)

Discoveredneutronsinnucleus– enablingotherscientiststoaccountformassofatom.

Discoveryofthenucleus

Nuclear

fissio

n One largeunstablenucleussplitstomaketwosmallernuclei

Neutronhits U-235nucleus, nucleusabsorbsneutron,splitsemittingtwoorthreeneutronsandtwosmallernuclei.

Processalsoreleasesenergy.

Processrepeats, chainreactionformed

Usedinnuclear powerstations

Nuclear

fusio

n Twosmallnucleijointomakeonelarger

nucleus

DifficulttodoonEarth– hugeamountsofpressureandtemperature

needed.OccursinstarsPH

YSICSONLY:

Nuclearene

rgy

Fuelrods MadeofU-238,‘enriched’withU-235(3%).Longandthintoallowneutronstoescape, hittingnuclei.

Control rods MadeofBoron.Controlstherateofreaction.Boronabsorbsexcessneutrons.

Concrete Neutronshazardous tohumans– thickconcreateshieldprotectsworkers.

Decay Rangeinair Ionisingpower Penetrationpower

Alpha Fewcm Verystrong Stoppedbypaper

Beta Fewm Medium StoppedbyAluminium

Gamma Great distances Weak Stoppedbythicklead

Radiusofanatom1X10-10m

Radioactivedecay

Unstableatomsrandomlyemitradiationtobecomestable

Detecting UseGeigerMullertube

Unit Becquerel

Ionisation Allradiationionises

Isotope

Differentformsofanelementwiththesamenumberofprotonsbutdifferentnumberofneutrons

𝑈"##$% → 𝑇ℎ + 𝐻𝑒#

-".#$-

𝐶01- → 𝑁 + 𝑒31.

41-

𝑇𝑐-$"" → 𝑇𝑐 + 𝛾-$

""

Contamination Unwanted presenceofradioactiveatoms

Irradiation Personisinexposed toradioactivesource

Sievert Unitmeasuringdoseofradiation

BackgroundConstant lowlevelenvironmentalradiation,e.g.fromnucleartesting,nuclearpower,

waste

Halflife

Thetime takentolosehalfofitsinitialradioactivity

Uses Different isotopeshavedifferenthalflives Shorthalf-livesusedinhighdoses,longhalflivesusedinlowdoses.

Tracers UsedwithinbodyIsotopewithshorthalflife injected,allowedtocirculate andcollectindamagedareas.PETscannerusedtodetectemittingradiation.Mustbebetaorgammaasalphadoesnotpenetratethebody.

Radiationtherapy

Usedtotreat illnessese.g.cancer

Cancercellskilledbygammarays.High doseusedtokillcells.Damagetohealthycellspreventedbyfocussedgammaraygun.

Decay EmittedfromnucleusChangesinmass

numberandatomicnumber

Alpha(α) Heliumnuclei( 𝑯𝒆𝟐𝟒 ) -4 -2

Beta(β) Electron( 𝒆3𝟏𝟎 ) 0 +1

Gamma(γ) Electromagneticwave 0 0

Neutron Neutron -1 0