Dark, matt surfaces emit
more radiation than light ,
shiny surfaces
DARK MATT SURFACES
BETTER: absorbing
radiation than light
and shiny surfaces.
BECAUSE
*has lots of
cavities -
which trap
and absorb
the radiation
Conduction & Convection
Metals conduct better than non metals
BECAUSE * They contain FREE
ELECTIONS, which move around
randomly inside the metal and they hold
positive ions together.They collide with
each other and with the positive ions.
IONS are
charged
particles
EXAMPLE: a rod being heated, free
electrons on the hot end gain kinetic
energy and more faster.The electrons
then 'Defuse'/spread out and collide
with other free electrons = They transfer
kinetic energy to there electrons and
ions = energy transfer has occured
Convection ONLY takes
place in Fluids (gases or
liquids)
EXAMPLE: hot
water tank, hot water
from the boiler rises
and flows into the
tank where it rises to
the top.
Takes place due to
CIRCULATION
CURRENTS in the
fluid
Conduction
ONLY takes
place in Solids
Artificially modifying heat transfer at home
Roof 25%
Windows 10%
Doors 15%
Walls 35% Floor
15%
Sometimes we need o control heat
transfer, for example , a car engine which
overheats could go up in flames.