P3

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  • P3- Sustainable energy
    • Energy sources
      • Energy is conserved
      • Primary energy sources- naturally occur or can be found
      • Electricity is a secondary energy source
      • Fossil fuels are built up over millions of years by the decay of plants and animals
        • Produce pollutants
      • Our current energy sources are not reliable
    • Measuring energy
      • Energy used on an electrical device can be measured using a meter
      • The energy depends on:
        • The power rating on the appliance
        • The time it is on for
      • Power is the rate energy is used
      • 1 watt is 1 joule of energy per second
      • One kilo-watt is a thousand watts
      • Energy used(J/KW)= power rating (W/KW)x time (s/h)
      • Cost of energy(p)=  units used (w/kw)x price
      • Power (W) = Voltage x current (A)
      • Daily energy use (kWh per day)= energy needed to produce the item (kWh)/ number of days the item lasts
    • Global problems
      • Richer countries use more enrgy
    • Efficiency
      • Efficiency= useful energy transferred/ energy supplied to appliance x100
    • Sankey diagrams
      • Branching arrows show how energy is transferred
      • Width indicates the amount of energy
    • Generating electricity
      • Generators work using electromagnetic induction
      • Move a magnet through coils of wire
        • More coils, faster
      • Causes voltage induction
      • Rotate magnet near coil
        • Alternating current
          • Move a magnet through coils of wire
            • More coils, faster
    • Burning fuels
      • Thermal power stations
        • High pressure steam made from burning fuel
          • Turns turbine
            • Turns generator
              • Goes to a transformer then to elctricty lines
    • Reducing waste
      • Burning fuel produces CO2 and other waste products
      • Burning natural gas is more efficient
    • Nuclear power
      • In a nuclear reactor uranium atoms split into lighter atoms
        • Releases energy (heat)
          • Used to heat water to create steam
      • Both the fuel and waste are radioactive
      • Contamination- When it gets inside something
      • Irradiation- exposure to radiation
    • Renewable
      • Solar power
        • Using photovoltaic panels
      • Hydroelectric
        • Using the power of water flowing from higherground
      • Wind power
        • Wind turns turbines
      • Waves
      • Bio fuel
    • Distributing electricity
      • National grid
        • Network of wires and transformers
      • More efficient to use a higher voltage
      • Use transformers
        • Step up transformer- Output is bigger than input and current is reduced

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