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ENERGY & ELECTRICITY…read more

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Heat Transfer
Heat is a type of energy which will flow from a warmer area to a colder one.
The bigger the temperature difference the faster heat is transferred.
The bigger the surface area, the more waves can be emitted from the surface, so the quicker
the transfer of heat.
Heat is transferred in three different ways:
RADIATION
CONDUCTION
CONVECTION…read more

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Heat Radiation
Heat radiation can also be called infrared radiation. It is when heat moves around in
electromagnetic invisible waves. It can carry energy through anything as it doesn't need
particles to move.
· dark matt colours absorb and emit much more radiation
· light shiny colours will reflect nearly all the radiation all objects above absolute zero
That is why we get: are continually emitting and
Matt black solar hot water panels that easily absorbs a lot absorbing heat radiation
of heat and the shiny inner surface to keep absorbed heat · hot objects: emit more infra
in. red than it absorbs
Silver survival blankets that help stop their body heat · cold objects: absorb more
radiating away, which could save someone's life. infra red than it emits
· the smaller the volume/mass
the faster the temperature
change
· the larger the surface area
the faster the rate of heat
transfer
· the larger the temperature
difference to the surroundings
the faster the rate of heat
transfer…read more

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Heat Conduction
Conduction of heat is when vibrating particles collide and pass on their extra kinetic energy. It
occurs mainly in solids.
· Metals are good
conductors of
heat because
they have
electrons which
can move freely.
· Poor conductors
of heat like wood
and plastic are
called insulators.
· Particles are
involved and
needed for
conduction.…read more

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Heat Convection
Convection of heat occurs when the more energetic particles move from the hotter region to
the cooler region and take their heat energy with them. Convection currents are all about
changes in density. It only happens in liquids and gases as the particles are needed to move
around. We can show a convection current using a cold beaker of water, solid lump of
potassium permanganate (coloured crystal) and a heat source.
1) Particles are heated and gain kinetic
energy, causing them to spread out and
expand.
2) This means there is more distance
between them making them less dense.
3) Reduction in density means the hotter
air rises above the denser cooler air,
moving it out of the way and making it
fall towards the area being heated.
4) The hot air is receiving less heat to
loses kinetic energy causing it to contract
making it more dense.
5) As it is more dense it sinks back down
while the cold air being heated rises.…read more

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