Energy

Energy

Conduction
1. Occurs in mainly solids because you need collision for it to be conduction
2. It means to pass on extra kinetic energy from vibrating particles into neighbouring particles
3. Metals are good conductors
  1. This is because the electrons are free to move inside
    1. Transfer energy from hot to cold, by giving extra kinetic energy
4. Its faster in denser solids, because particles are closer together
  1. Materials with large spaces between particles take longer to conduct heat. These are called insulators
Condensation
1. when gas cools, particles in the gas slow down and lose kinetic energy - pulling them closer together
  1. Sometimes if particles are too cold then the gas comes a liquid
2. Condensation is faster if...
  1. temperature of the gas is lower
  2. temperature of the surface area the gas touches is lower
  3. density is higher
  4. Airflow is less
Heat radiation
1. Transferred by infrared radiation
  1. Its emitted by solids, liquids and gases
2. Emitted from the surface of an object
  1. objects hotter than its surroundings emits more radiation than it absorbs
  2. Objects cooler than its surroundings absorbs more radiation than it emits
3. Depends on surface colour and texture
  1. Dark, matte surfaces absorb infrared radiation falling on them and also emit much more
  2. Light, shiny surfaces reflect a lot of infrared radiation falling on them.
  3. Vacuum flasks have silver inner surfaces to keep heat in or out, depending on whether its storing hot or cold liquid
Convection
1. Occurs in mainly gases and liquids
  1. Like in kettles and immersion heaters
    1. Particles near coils gain more energy so they move around faster, so there is more space between particles causing it to become see dense - therefore rising
2. Occurs when more energetic particles move from the hotter region to the cooler region - taking heat energy with them
3. Convection never happens in solids because the particles cannot move
4. Its all about changes in density
  1. Hotter water becomes less dense so it rises
  2. Cooler water becomes more dense so it sinks
Evaporation
1. Faster particles are most likely to evaporate
  1. When they do the speed and kinetic energy of the remaining particles decreases
2. Evaporation is faster if...
  1. Temperature is higher
  2. Density is lower
  3. Surface area is larger
  4. Airflow over the liquid is greater

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	Created by Georgie Liddle about 7 years ago