Conduction, Infra-red,insulating and electricity

• Conduction means the transfer of energy by collisions
• Non-metals have low thermal conductivity because they can only collide with their neighbours.
• In metals(and graphite) there are delocalised(free) electrons. They have high thermal conductivity because the free electrons can transfer energy quickly.
• Infra-red is emitted by all objects
• The higher the temperature of an object the higher the infra-red
• An object at a constant temperature emits a continuous spectrum(range) of frequencies to a maximum.
• Matt black is the best at emitting and absorbing Infra-red radiation
• Shiny white or silver is the best at reflecting Infra-red radiation.
• Change in energy=mass x specific heat capacity x temperature change.
• Most of the heat lost from houses is through the roof.
• Double glazing works by preventing conduction transferring heat out of the house and is a more efficient method of insulation that single glazing
• The types of insulation are;

  • fibre glass
  • double glazed windows
  • thicker walls
  • hot water tank jackets
  • draught-proofing
  • thick curtains
• Shiny foil stuck behind radiators prevents/reduces radiation by reflecting infra-red back into the room. However most people don't like the look of it and you don't save much.
• Opposite charges attract
• “Like” charges repel