thermal energy transfer

• conduction definition


  the way in which heat energy is transferred in solids
• convection definition


  when the particles move due to a change in density, mostly in liquids.
• radiation definition (infrared)


  all objets that are above 0 degrees will radiate thermal energy as electromagnetic waves
• whats common between conduction and convection?

  they both have particles that gain kinetic energy
• when water is heated..

  • .. it expands (distance)
  • .. it becomes less dense
  • .. and rises
• cooler denser water moves in..

  • .. and is heated in turn (by the active kinetic energy)
  • .. and rises
• as the warm water rises..

  • .. it cools (kinetic energy decreases)
  • .. becomes denser (particles get closer)
  • .. and falls again
• a grill cooks food by... 


  ... transferring heat to it by emitting radiation
• how does the suns energy get through to us?

  due to infrared radiation travelling through space - it needs no medium
• the best colour for absorbing and radiation heat is?

  black because it absorbs all the colours
• the transfer of heat when gas or liquid particles heat us and rise is?


  convection
• changing a gas into a liquid

  condensation
• very good conductor of heat 


  metal
• when air cools down it...


  sinks
• when air is heated because it becomes less dense and 


  rises
• doesnt let heat conduct through it very well


  insulator (plastics)
• very good insulator, used in hot flasks, where there are no air particles

  vacuum
• transfer of heat that can travel thru a vacuum

  radiation (infrared)
• a large _____ means that the object cools down quicker

  surface area
• unit of measurement for heat 


  huoles or calories
• thermal equilibrium


  when both objects (hot and cold) reach the same temperature
• when an object is heated 


  the particles vibrate mroe
• when an object is heated, the particles gain energy in thier..

  kinetic energy stores
• conduction only occurs when ____ particles pass on their extra energy to ________

  vibrating particles, neighbouring particles
• conduction only takes place when


  the particles are touching
• all objects radiate invisible _____ that carry energy to the surroundings

  waves