Heat Transfer
Heat
is a form of energy. It
is measured in joules (J). It
can be measured with a joule-meter or a combination of instruments,
the readings of which can be used to perform a calculation to establish
the value.
Heat
always flows from hot areas to cold areas (See U-values )
The
bigger the difference in temperature between two objects the faster
the heat will move (See the pressure cooker )
The
bigger the area of contact between the two objects the faster the
heat transfer will happen.
Heat
moves easily through good conductors of heat (such as metals) and
very slowly through heat insulators (such as trapped air pockets, wood or plastic). See double glazing and cavity wall insulation.
Heat radiation is absorbed/emitted readily
by dark, dull, rough surfaces and less easily by light, shiny,
smooth surfaces.
'Heat' is often confused with 'temperature' - see this page. Make sure you know the difference!
There
are three methods of heat transfer: conduction, convection and radiation
The link takes you through to some sample questions.
The solutions do not just give you the 'answer required' but also have comments to explain why the examiner looks for particular words or phrases in an answer.
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