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Slide 1

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Keywords: Conduction, convection, radiation, kinetic, gravitational, chemical, elastic
Radiation
Conduction-energy is transferred via
particles colliding. It happens quicker Travel as waves, known as
in solids due to particles being close thermal/infra red radiation. The
together. It is quick in metals as heat from the sun
electrons are free to move throughout reaches us in this way,
metal.
the waves can travel through a
Convection- Liquids and gases expand when they are heated. The particles
vacuum.
move faster and the gap between particles widens. The liquid or gas in hot
areas is less dense than the liquid or gas in cold areas, so it rises into the cold
areas. The denser cold liquid or gas falls into the warm areas. In this way,
convection currents are set up Emitters of radiation
Heat Heat moves
White/silver surfaces emit less
thermal radiation. Polar bears are
Types of Energy white so they emit less thermal
-Light radiation.
-Sound
-Gravitational Potential (objects above the
Earths surface have this)
Reducing Heat Loss Examples
-Electrical
-Flasks have a vaccum layer so
-Kinetic (moving)
conduction and convection don't
-Chemical occur.
-Elastic (stretched or compressed objects) Energy Efficiency -Silver materials used so less
Efficiency = useful energy out thermal radiation emitted.
-Thermal
total energy in -Larger objects have a smaller
-Nuclear
surface area : volume ratio so less
To convert to a percentage x 100! heat is lost.
The Energy Law
-Loft insulation as hot air rises
Energy can't be created or destroyed it is just (convection)
Electrical Light 15J(useful)
transferred into different forms. It is measured in
Joules (J) 20J Heat 5J (wasted) -Double glazing has a layer of air as
conduction is slower in gases.
Efficiency = 15
20
=0.75
Electrical Heat (useful)
Light/sound (wasted)
Keywords: Efficiency, power, joule, nuclear, geothermal. Greenhouse effect, thermal, vacuum, renewable, turbine, generator.…read more

Slide 2

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Power Electricity Costs Fossil Fuels
Coal (highest start up time), oil and gas (shortest
Power (W)= energy (J) Measured in kilowatt-hours (kWh) the cost per unit also
start up time). Disadvantages
needs to be known.
time (s) -Carbon dioxide produced ­global warming
Energy used (kWh) = power (kW) x time (hours) -Sulphur dioxide produced (acid rain)
Power is the rate at which
Take care with units! -Non renewable
energy is transferred.
1 watt means 1 joule of
Nuclear
energy is transferred every Wind
Chemical reactions involving uranium and
second. Advantages ­ no Greenhouse gases produced,
plutonium release heat which is used to
renewable, no fuel costs
boil water in power stations.
Disadvantages ­ noise and visual pollution, won't
Advantages ­ no Greenhouse gases
always work
produced
Disadvantages ­ non renewable,
hazardous waste produced
Geothermal
which must be dealt with.
Cold water is heated using rocks within the
Earth, the resulting steam is used to drive
Water (tidal, wave & hydroelectric) turbines.
The movement of water is used to drive Advantages ­ renewable, no fuel costs, no
turbines. harmful gases
Advantages ­ no Greenhouse gases Disadvantages ­ very few suitable sites.
produced, renewable, hydroelectric and
Electricity and The National Grid tidal are reliable
Colours
1- Fuel is burnt to heat water to make steam Disadvantages ­ can only be used in
certain locations, loss of habitats and Dark colours absorb more heat.
2- The steam is used to spin a turbine
farmland. Light colours reflect more heat
3-The spinning turbine spins a generator which produces
electricity.
4- The electricity goes to transformers to produce the Solar
correct voltage Solar cells convert light into electricity.
Step up transformers increase the voltage, step down Solar panels are used to heat water
transformers reduce voltage. The National Grid carries Advantages ­ renewable, no fuel costs,
energy at a low current as this means less energy is lost as no harmful gases produced
heat, but it requires a high voltage. Extra Notes
Disadvantages ­ expensive and
inefficient, need a sunny climate, won't
work at night.…read more

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