GCSE›Edexcel GCSE Physics›Mind mapsEfficiency & Energy ResourcesEdexcel GCSE Physics: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsEfficiencyefficiency=useful energy outtotal energy in\text{efficiency} = \frac{\text{useful energy out}}{\text{total energy in}}efficiency=total energy inuseful energy outDecimal has no unitsMultiply by 100 for a percentageNo device is 100% efficientLamp: 20 J of 100 J = 20%Raising efficiencyLubricate moving parts to reduce frictionImprove thermal insulationStreamlining reduces resistive forcesCut a specific wasted transferNon-renewableFossil fuels: coal, oil, natural gasNuclear fuelUsed faster than replacedWill eventually run outEfficiencyand energy resourcesJ%RenewableBio-fuel, wind, hydroelectricityTides and the SunNaturally replenishedWind and solar depend on weatherUses and trendsFossil fuels release carbon dioxideNuclear: reliable, no direct CO₂, waste concernRenewables often cost more to set upTrend: more renewables, fewer fossil fuelsExam tipsLink efficiency to a specific wasted transferRenewable does not mean no impact