1.1.1 Infrared radiation is
energy transfer by
184.108.40.206 All objects emit infrared radiation.
220.127.116.11.1 The hotter an object is , the more
infrared radiation it emits in a given
18.104.22.168.1.1 Infrared radiation can travel
through a vacuum because it doesn't
involve particles, that's how we get
heat from the sun.
1.2 1.2- Surfaces and radiation
1.2.1 Dark, matt surfaces emit infrared
radiation more quicker than light,
shiny surfaces so it will tranfer
energy and cool down quicker.
22.214.171.124 Dark, matt surfaces absorb
infrared radiation more quickly
than light, shiny surfaces so it
will get hotter.
126.96.36.199.1 Light, shiny surfaces reflect more
infrared radiation than dark, matt
1.3 1.3- States of matter
1.3.1 Flow, shape, density and volume are
the properties used to describe each
state of matter.
188.8.131.52 The particles in a solid are held
next to each other, vibrating in
their fixed positions.
184.108.40.206.1 The particles in a liquid move about
at random and are in contact with
each other ( they can flow).
220.127.116.11.1.1 The partices in a gas move about
randomly and are much farther
apart than particles in a solid or
liquid so it can flow. They also move
faster and and gas is less dense than
a solid or a liquid.
1.4 1.4- Conduction
1.4.1 Metals are the best conductors.
18.104.22.168 Materials such as wood and fibreglass
are good insulators because they contain
22.214.171.124.1 Conduction in a metal is mainly due to free
electrons tranferring energy inside the metal
when they gain kinetic energy.
126.96.36.199.1.1 Non-metals are poor
conductors because they do
not contain free electrons.
188.8.131.52.1.1.1 Conduction occurs mainly in solids because
most liquids and gases are poor conductors. If
one end of a solid is heated, the particles at
that end gain kinetic energy and vibrate
more. this energy is passed to neighbouring
particles and in this way energy is transferred
through the solid.
1.5 1.5- Convection
1.5.1 Convection is the circulation of a
fluid (liquid or gas) caused by
184.108.40.206 Convection takes place only in liquids and
220.127.116.11.1 Heating a liquid or a gas makes
it less dense so it rises and
18.104.22.168.1.1 When a fluid is heated, it expands causing it
to become less dense and rise. The warm
liquid is replaced by coller, denser fluid. The
resulting convetion current transfers energy
throughout the fluid.
1.6 1.6- Evapouration and
1.6.1 Evapouration is when a liquid turns
into a gas. Evapouration takes place
because the most energetic liquid
molecules escape from the liquids
surface and enter the air. Therefore
the average kinetic energy of the
remaining molecules is less so the
temperature of the liquid decreases.
22.214.171.124 Condensation is when a gas turns into
a liquid. This often takes place on cold
surfaces such as windows and
126.96.36.199.1 The rate of evapouration is increased by:
increasing the surface area of the liquid,
increasing the temperature of the liquid and
creating a draught of air across the liquid's
188.8.131.52.1.1 The rate of condensation is increased by:
increasing the surface area and reducing the
1.7 1.7- Energy transfer by design
1.7.1 The rate of energy transfer to or from an
object depends on: the shape, size and type
of material of the object, the materials the
object is in contact with and the
temperature difference between the object
and its surroundings.
184.108.40.206 To maximise the rate of energy transfer and
keep things cool, we might use things that are:
good conductors, painted black and have the
air flow around them maximised.
220.127.116.11.1 To minimise the rate of energy
transfer and keeps things warm, we
might use things that are: good
insulators, white and shiny and
prevent currents by trapping air in
1.8 1.8- Specific heat capacity
1.8.1 The greater the mass of an object, the
more slowly its temperature increases
when it's heated and the more energy
18.104.22.168 The rate of temperature change in a
substance when heated depends on
the energy transferred to it, its mass
and its specific heat capacity.
22.214.171.124.1 Specific heat capacity is the amount of
energy needed to heat 1 kilogram of a
substance by 1 degree Celsius.
1.9 1.9- Heating and insulating buildings
1.9.1 The rate of energy transfer to and from
our homes can be reduced.
126.96.36.199 U-values tells us how much energy per
second passes through different materials.
The lower the U-value the better the
material is as an insulator.
188.8.131.52.1 Solar heating panels do not use fuel to heat
water (they use radiation from the sun) and are
cheap to run but they are expensive to buy and
2 2. Using Energy
2.1 2.1- Forms of energy
2.1.1 Energy exists in different forms.
184.108.40.206 Energy can be transferred from one form into another form.
220.127.116.11.1 When an object falls and gains speed, its
gravitational potential energy decreases
and its kinetic energy increases.
18.104.22.168.1.1 Energy exists in different forms such as: light,
sound, heat, kinetic, nuclear, electrical,
gravitational potential, elastic potential and
2.2 2.2- Conservation of energy
2.2.1 Energy can be transferred from one
form to another or from one place to
22.214.171.124 Energy cannot be created or destroyed.
126.96.36.199.1 Conservation of energy applies to all energy changes.
188.8.131.52.1.1 Conservation of energy means the total
amount of energy is always the same.
2.3 2.3- Useful energy
2.3.1 Useful energy is energy in the place we
want it and the form we need it.
184.108.40.206 Wasted energy is energy that is not useful energy.
220.127.116.11.1 Useful energy and wasted energy both end up
being transferred to the surroundings, which
18.104.22.168.1.1 As energy spreads out, it gets more and more
difficult to use for further energy transfers.
22.214.171.124.1.1.1 Energy is often wasted because of friction
between the moving parts of a machine. This
energy warms up the machine and its
126.96.36.199.188.8.131.52 Sometimes friction can be useful, for example in
the brakes of a bicycle or a car. Some of the kinetic
energy of the vehicle is transferred to energy
heating the brakes.
2.4 2.4- Energy and efficiency
2.4.1 The efficiency of an appliance = useful
energy transferred by the appliance divided
by total energy supplied to the appliance
184.108.40.206 No machine can be more than 100% efficient.
220.127.116.11.1 Measures to make machines more efficient include
reducing: friction, air resistance, electrical
resistance and noise due to vibrations.
18.104.22.168.1.1 The energy transfer through an appliance
can be represented by a sankey diagram.
3 3. Electrical Energy
3.1 3.1- Electrical appliances
3.1.1 Electrical appliances can transfer electrical
energy into useful energy at the flick of a
22.214.171.124 Uses of everyday electrical energy appliance
include: heating, lighting, making objects
move and creating sound and visual images.
126.96.36.199.1 An electrical appliance is designed for a
particular purpose and should waste as
little energy as possible.
3.2 3.2- Electrical power
3.2.1 Power is rate of transfer of energy.
188.8.131.52 Power = Energy divided by time taken (in seconds) for
the energy to be transferred.
184.108.40.206.1 An appliance with 1 Watt transfers 1 Joule of
electrical energy to other forms of energy
3.3 3.3- Using electrical energy
3.3.1 The kilowatt-hour is the energy supplied to a
1kW appliance in 1 hour.
220.127.116.11 Energy transferred in kWh = Power of the
appliance x the time taken for energy to be
18.104.22.168.1 Total cost = number of kWh x cost per kWh.
3.4 3.4- Cost effectiveness matters
3.4.1 Cost effectiveness means getting the best value for money.
22.214.171.124 To compare the cost effectiveness of
different appliances, we need to take
account of a number of different
126.96.36.199.1 The costs may include: the cost of buying the
appliance, the cost of installing the appliance,
the running costs, the maintenance costs,
environmental costs and the interest charged
on loan to buy the appliance.
188.8.131.52.1.1 The payback time is the time it takes for an
appliance or installation to pay for itself in
terms of energy savings.
184.108.40.206.1.1.1 Payback time (in years) = Cost of installation
divided by savings per year
4 4. Generating electricity
4.1 4.1- Fuel for electricity
4.1.1 Electricity generators in power
stations are driven by turbines.
220.127.116.11 Coal, oil and natural gas are burned in
fossil-fuel power stations.
18.104.22.168.1 Uranium or Plutonium is
used as the fuel in a nuclear
22.214.171.124.1.1 Biofuels are renewable
sources of energy which can
126.96.36.199.1.1.1 Most power stations burn fuels to
produce energy to heat water. In a
nuclear power station uranium is not
burned; the energy comes from the
process of nuclear fission.
188.8.131.52.184.108.40.206 Nuclear power stations don't release
greenhouse gases unlike fossil-fuel
power stations but they do produce
radioactive waste that must be stored
safely for a long time.
4.2 4.2- Energy from wind and water
4.2.1 A wind turbine is an electricity
generator on top of a tall tower.
220.127.116.11 Waves generate electricity by
turning a floating generator.
18.104.22.168.1 Hydroelectricity generators
are turned by water running
22.214.171.124.1.1 A tidal power station traps each
high tide and uses it to turn
4.3 4.3- Power from the Sun and the Earth
4.3.1 Solar cells transfer solar energy directly into
126.96.36.199 Solar heating panels use the Sun's
energy to heat water directly.
188.8.131.52.1 Geothermal energy is produced inside the
Earth by radioactive processes and this
heats the surrounding rock. In volcanic or
other suitable areas, very deep holes are
drilled and cold water is pumped down to
the hot rocks. There it is heated and comes
back to the surface as steam which is used
to drive turbines that turn generators and
so electricity is produced.
184.108.40.206.1.1 Solar energy from the Sun travels
through space to the Earth as
4.4 4.4- Energy and the environment
4.4.1 Burning fossil fuels produces
greenhouse gases that cause
220.127.116.11 Nuclear fuels produce radioactive waste.
18.104.22.168.1 Using renewable energy resources
can affect plant and animal life.
4.5 4.5- The National Grid
4.5.1 The National Grid
distributes electricity from
power stations to our
22.214.171.124 Step-up and step-down
transformers are used in the
126.96.36.199.1 A high grid voltage reduces energy
wastage and makes the system more
efficient. Step-up transformers increase
the voltage before it is transmitted across
188.8.131.52.1.1 Step-down transformers decrease
the voltage to 230V so it is safe to
use in our homes.
4.6 4.6- Big energy issues
4.6.1 Gas-fired power stations and
pumped-storage power stations can
meet variations in demand.
184.108.40.206 Nuclear, coal and oil power
stations can meet base-load