Energy Transfer by heating
- Created by: levell2000
- Created on: 06-04-15 14:21
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- Energy Transfer by Heating
- Infrared Radiation
- Every object emits infrared radiation!
- The hotter the object is, the more infrared radiation is emitted
- It is energy transfer by electro-magnetic waves.
- Dark, matt surfaces are good absorbers and good emitters
- Light, shiny surfaces are poor absorbers and emitters but good reflectors
- Kinetic Theory
- Solids, Liquids and Gases have a different amount of energy
- Energy transfer by heating
- The transfer of energy by conduct, convect, evapo and conden involves particles
- Metal is the best conductor -> free electrons.
- Convection only occurs in gas and liquid
- evaporation -> liquid to gas
- condensation -> gas to liquid
- Rate of evaporation increasing the SA, increase temp, draught
- Condensation -> increase SA and reduce temp
- Energy transfer by design
- The rate depends on: shape, size and material. Materials it is in contact with. Temp difference
- Vacuum Flask
- Vacuum cuts out conduct and convect
- Glass = poor conductor -> little conduct
- Silvery outer reduces radiation
- double walled good insulator
- Plastic cap cuts evapor and conduct
- Heating and Insulating Buildings
- Insulation = loft insulation, cavity wall, double glazing, draught proofing, aluminium foil behind radiators
- U-values tell us how much energy per second passes through materials
- Solar heating panels do not use fuel to heat water but they are very expensive to buy and install
- Infrared Radiation
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