chapter 11 Flashcards

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1
Q

conduction

A

main method of thermal energy transfer in solids

  • metals are good at conducting heat
  • poor conductors = insulators
  • materials containing small pockets of trapped air are good at insulating as air is a gas and hence a poor conductor
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2
Q

conduction occur?

A

the atoms in a solid vibrate and bump into each other, lattice vibration of copper ions and the movement of delocalised electrons
Eg metals are good at conducting

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3
Q

convection

A

main way heat travels through liquid and gasses

  • when liquid or gasses are heated the particles push each other apart making gas/liquid expand making them less dense than surroundings
  • the hot liquid/gas rises, the cooler surrounding liquid/gasses move into take their place
  • eventually the liquid/gas cools, contracts and sinks back down

=the resulting motion is call convection

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4
Q

convection def

A

heat energy transfer in liquid or gas resulting in the change of density

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5
Q

radiation

A

-all hot objects give off thermal radiation =hotter they are, more they emit
thermal radiation = infrared (electromagnetic spectrum)
-thermal radiation is the only way heat can travel through a vacuum

darker =  good absorber and good emitter 
lighter = poor absorber and poor emitter
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6
Q

factors affecting emissions of radiation

A
  • temp = hotter = more radiation
  • colour= black = more radiation
  • surface area = greater = more area for radiation to be emitted from
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7
Q

home insulation

A
  • think curtains, draught excluders = stops convection currents, prevents cold area entering and warm leaving
  • loft and underfloor insulating materials = prevents conduction of heat through floors and ceilings
  • double and triple glazing windows = vacuum between glass panes cuts out losses by conduction convection
  • cavity walls =reduces heat losses by conduction
  • foam or rockwool in wall cavity = further reduces heat losses by convection
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8
Q

convection, climate and weather

A

convection currents are the orgins of winds and ocean currents, two major factors that control climate patterns around the world

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