Energy REvision map

  • Created by: DGL
  • Created on: 28-03-21 20:34
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  • Energy
    • Energy and temperature
      • Temperature is measured in degrees Celsius (°C).
      • Internal (thermal) energy is measured in joules (J).
        • The amount of thermal energy stored in something depends on:
          • ?      how hot it is (its temperature)
          • ?      the material it is made from
          • ?      its mass.
      • When two objects are at different temperatures, energy will be transferred from the hotter one to the cooler one until they are at the same temperature.
    • Transferring energy by heating
      • Energy can be transferred by heating in different ways.
        • Evaporation  can take place from a liquid at any temperature.
          • When part of a liquid evaporates, it is the fastest-moving particles that escape to form a gas.
            • The particles that are left are storing less energy as movement and so the temperature of the remaining liquid is lower.
        • Conduction takes place in solids and can also happen in liquids (although not very well). 
          • The particles in a solid are held together tightly. 
            • When they gain energy they vibrate faster and further, and the vibrations are passed on.
              • Metals are the best conductors. 
                • Most other solids are poor conductors.
        • Convection takes place in fluids (liquids and gases).
          • When part of a fluid is heated, the particles spread further apart and the fluid becomes less dense.
            • This makes it rise. As it rises it meets cooler fluid and passes the energy on. More cool fluid moves in to replace the rising fluid, setting up a convection current.
        • Infrared radiation can transfer energy through empty space and also through transparent materials. 
          • Any hot or warm object gives off or emits radiation.
            • When something takes in energy from radiation, it is said to absorb it.
    • Power
      • Power is the rate at which energy is transferred.
        • Power is measured in watts (W) or kilowatts (kW).
    • Efficiency
      • Not all energy is transferred usefully. Wasted energy is often transferred by heating. The percentage of useful energy produced by something is known as its efficiency.
        • Sankey diagrams shows the energy transfers 
          • The width of each arrow shows the amount of energy it represents. 


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