| Conduction,
convection and radiation - heat transfer |
PHY1H |
| 11.1 |
How
is heat (thermal energy) transferred and what factors affect the
rate at which heat
is transferred?
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Sometimes
we want to transfer heat effectively from one place to another.
At other times we want to reduce the rate of heat loss as much as
we can. To be able to do either of these things we need to know
how heat is transferred and which methods |
Distinguish between heat and temperature |
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Candidates
should use
their skills, knowledge and understanding of how science works:
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• to evaluate ways in which heat is transferred in and out of bodies
and ways in which the rates of these transfers can be reduced. |
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Their
skills, knowledge and understanding of how science works should
be set in these substantive contexts:
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• Thermal (infra red) radiation is the transfer of energy by electromagnetic
waves.
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• All bodies emit and absorb thermal radiation. |
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• The hotter a body is the more energy it radiates. |
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• Dark,
matt surfaces are good absorbers and good emitters of radiation.
• Light,
shiny surfaces are poor absorbers and poor emitters of
radiation.
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• The transfer of energy by conduction and convection involves particles
and how this transfer takes place. |
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• Under
similar conditions different materials transfer heat at different
rates.
• The
shape and dimensions of a body affect the rate at which it transfers
heat.
• The
bigger the temperature difference between a body and its surroundings,
the faster the rate at which heat is transferred.
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See U-values |
