P1.1.3 Energy transfer by heating (cont)

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GCSE Physics (P1.1 Infrared Radiation) Mind Map on P1.1.3 Energy transfer by heating (cont), created by fampulli on 06/01/2014.
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Resource summary

P1.1.3 Energy transfer by heating (cont)
  1. energy transfer by design
    1. factors which affect the rate of heat energy transfer
      1. surface area and volume
        1. heat energy is radiated from the surface of an object
          1. thus, the bigger the surface area (s.a.), the more infrared waves that can be emitted from (or absorbed by) the surface
            1. so, the quicker the transfer of heat
              1. applications of this
                1. 'fins'
                  1. for heat sinks in computers, and car and motorbike engines, increasing the the s.a., so transfer and therefore heat loss is quicker
                    1. If temp and s.a are constant, a smaller volume- greater rate of heat energy transfer
                      1. as more of the object will be in contact with the surroundings
                    2. heat sinks have large s.a's so they can transfer heat energy as quickly as possible away from e.g. computer components
            2. the material from which the object is made from
              1. Objects made from good conductors (like metals) transfer heat energy away more quickly than insulating materials (like plastic)
              2. the nature of the surface with which the object is in contact
                1. Again, if the object is in contact with a good conductor, as opposed a good insulator, the heat will be conducted away much faster
              3. some devices are designed to limit transfer
                1. vacuum flasks
                  1. double-walled with a vacuum between the walls
                    1. stops all conduction and convection through the sides
                    2. walls are silvered
                      1. keeping heat loss by radiation to a minimum
                      2. insulating foam
                        1. minimises conduction through it
                        2. plastic stopper filled with cork or foam
                    3. Animal adaptations for energy transfer
                      1. fur (some animals) and hairs (humans) 'stand up' in cold weather
                        1. trapping a thicker layer of insulating air around the body
                          1. and limiting the amount of heat loss by convection
                        2. Too warm: blood diverts more blood to flow near the surface of the skin
                          1. so your skin might appear pink
                            1. increasing the amount of heat lost by radiation
                            2. relative ear sizes
                              1. Arctic foxes have evolved small ears
                                1. with a small surface are to minimise heat loss by radiation
                                  1. and conserve body heat
                                2. Desert foxes have huge ears
                                  1. with a large surface area to allow them to maximise heat loss
                                    1. and keep cool
                                  2. generally, animals in warmer climates have larger ears than those in cold climates, to help them control heat transfer
                                3. the bigger the temperature difference between an object and its surroundings, the faster the rate at which energy is transferred by heating
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