Download Revision Tips and Topics Summary for P1a File

Here are the topics covered in P1a, along with the key points. You could use your notes, revision
guide, Antonine education and other websites (BBC Bitesize seems quite good) to make your
own notes. Read these through and work through examples of problems. Condense these notes
to make your own key points. Test yourself. Make yourself a ticklist to monitor your progress.
Work through questions and answers on past papers.
1 Heat Transfer
1.1 Thermal Radiation
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Thermal radiation is energy transfer by electromagnetic waves.
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All objects emit thermal radiation
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The hotter an object is , the more thermal radiation it emits.
1.2 Surfaces and Radiation
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Dark matt surfaces are better emitters of thermal radiation than light shiny surfaces.
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Dark matt surfaces are better absorbers of thermal radiation than light shiny surfaces.
1.3 Conduction
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Conduction in a metal is due mainly to free electrons transferring energy inside the
metal.
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Non-metals are poor conductors because they do not contain free electrons.
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Materials such as fibreglass are good insulators because they contain pockets of trapped
air.
1.4 Convection
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Convection only takes place in liquids and gases (fluids).
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Heating a liquid or gas makes it less dense.
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Convection is due to a hot liquid or gas rising.
1.5 Heat Transfer by Design
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A radiator has a large surface area so that it can lose heat easily.
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Small objects lose heat more easily than large objects.
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Heat loss from a building can be reduced using:
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aluminium foil behind radiators
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cavity wall insulation
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double glazing
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loft insulation
2 Using Energy
2.1 Forms of Energy
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Energy exists in different forms
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Energy can change (transform) from one form into another form
2.2 Conservation of Energy
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Energy can be transformed from one form to another or transferred from one place to
another.
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Energy cannot be created or destroyed.
2.3 Useful Energy
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Useful energy is energy in the place where we want it and in the form we need it.
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Wasted energy is energy that is not useful energy.
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Useful energy and wasted energy both end up being transferred to the surroundings,
which become warmer.
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As energy spreads out, it becomes more and more difficult to use for further energy
transfers.
2.4 Energy and Efficiency
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Energy is measured in Joules.
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The efficiency of a device =
useful energy transferred by the device
total energy supplied to the device
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Wasted energy causes inefficiency
3 Electrical Energy
3.1 Electrical Devices
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Electrical energy is energy transfer due to an electric current
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Uses of electrical devices include heating, lighting, making objects move (using an
electric motor) and creating sound and visual images.
3.2 Electrical Power
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The unit of power is the Watt (W), equal to 1 J/s.
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1 kilowatt = 1000 Watts.
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Power (in Watts) =
energy transferred (in Joules)
time taken (in seconds)
3.3 Using Electrical Energy
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Energy transferred (kilowatt-hours, kWh) = power of device (kW) x time in use (hours,
h)
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Total cost = number of kWh used x cost per kW
3.4 The National Grid
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The National Grid is a network of cables and transformers.
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We use step-up transformers to step up power stations’ voltages to the grid voltage.
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We use step-down transformers to step the grid voltage down for use in our homes.
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A high grid voltage reduces energy loss and makes the system more efficient.
4 Generating Electricity
4.1 Fuel for Electricity
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Electricity generators in power stations are driven by turbines.
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Much more energy is released per kilogram from uranium than from fossil fuels.
4.2 Energy from Wind and Water
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A wind turbine is an electricity generator on top of a tall tower.
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A wave generator is a floating generator turned by the waves.
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Hydroelectricity generators are turned by water running downhill.
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A tidal power station traps each high tide and uses it to turn generators.
4.3 Power from the Sun and the Earth
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We can convert solar energy into electricity using solar cells or use it to heat water
directly in solar heating panels.
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Geothermal energy comes from the energy released by radioactive substances deep
inside the Earth.
4.4 Energy and the Environment

Fossil fuels produce greenhouse gases.

Nuclear fuels produce radioactive waste.

Renewable energy sources can affect plant and animal life.