Heat Transfer

Maths, Physics Revision

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Heat will try to move from an area
of high temperature to low temperature.
The bigger the difference in
temperature the greater the rate
of transfer. There are three ways heat is
transferred, Conduction, Convection
and Radiation

Conduction takes
place in a solid.
When the material
is heated the
atoms vibrate
faster. These
faster vibrations
are passed from
atom to atom until
all the atoms are
vibrating faster.
Hence heat energy
is transferred
through the solid.

convection

Because the same number of particles (ie same mass of particles)
occupy a greater volume it makes the heated air less dense than the
surrounding cold air. Less dense material always floats on more
dense fluids (gas or liquid) hence the heated air rises up and floats
on the more dense colder air. The same process can happen in a
liquid. This type of heat transfer is called CONVECTION

Radiation

Radiation does not
involve particles, It
is heat transfer by
electromagnetic waves
(see electromagnetic
spectrum, heat is the
Infrared part of the
spectrum). Because
particles are not
involved heat waves
can travel through a
vacuum. Heat from
the sun travels
through space, which
is a vacuum.

Dark objects absorb radiated heat better than light silver
objects . Play the above clip and see the temperature rise
in the dark can faster than the silver can. DARK OBJECTS
ALSO RADIATE HEAT BETTER THAN LIGHT SILVER
OBJECTS. If hot water were put in two the cans and the cans
were allowed to cool, the dark can would cool the fastest.