Making use of energy

• what causes energy to be transferred thermally

  temperature difference
• how does conduction occur in solids

  particles are regularly positioned and close together. The atoms in the hot part of the solid vibrate faster than those elsewhere. They pass on their energy to their neighbours by collisions so energy travels further the solid
• what makes metals the best conductors

  by free electrons which move at speed from the hot region colliding with metal ions in the lattice, transferring their energy in the process
• how does convection occur in liquids and gases

  when section of liquid or gas is heated the molecules gain energy and move more vigorously. liquid increases in volume and its density decreases. This less dense liquid rises and colder denser liquid sinks to takes place, continues until all liquid is heated.
• how do silver shiny surfaces reduce heat loss

  poor absorbers and emitters of radiation
• how do loft and cavity wall insulation reduce heat loss

  loft and cavity wall insulation contains trapped air. Air is a poor conductor and when trapped, cannot convect
• environmental benefits of house insulation

  reduces heat loss therefore fewer fossil fuels burned, less carbon dioxide produced and effects of global warming reduced.
• payback time


  insulation cost ÷ annual savings