PD2 ENERGY REVISION TOPICS

The Following topics are the MAIN areas of study for this unit for both Foundation and higher level candidates. It is advised that these areas should be revised in more depth.

NB ALL TOPICS IN THIS UNIT ARE NEEDED FOR THE YEAR 11 TERMINAL EXAM

    AREAS OF STUDY
    Types of Energy
    Heat Transfer
    Domestic Electricity
    Paying For Electricity

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1)TYPES OF ENERGY AND ENERGY TRANSFER

    a) TYPES OF ENERGY

HEAT,
LIGHT,
SOUND,
ELECTRICAL,
KINETIC,
POTENTIAL (ELASTIC, GRAVITATIONAL,CHEMICAL)

    b) ENERGY TRANSFER
Eg. A Car

CHEMICAL Þ KINETIC + HEAT + SOUND

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    Click here for the theory on heat transfer
  1. Conduction- Transfer of heat in solids by the kinetic energy of Particles- recognise good and bad conductors
  2. Convection- Transfer of heat in liquids and gases ( as the density changes)
  3. Radiation- Transfer of heat by waves (can travel through a vacuum-no particles needed)

INSULATION- How to prevent Heat Loss from each of the above especially in the context of a house
AIR AS AN INSULATOR- How trapped air in Fur, fibre glass etc prevents heat loss by Conduction
PAYBACK TIME (the time it takes to save enough money on heating bills to pay for installing the insulation)
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      A) WHY USE ELECTRICITY
      Electricity is easy to use, does not need stored and can be used for many tasks
      However, It can be dangerous and difficult to get to remote places

      B) THE 3 EFFECTS OF A CURRENT

      B) WIRING A PLUG In the UK 3 pin plugs are designed to carry 240V (50Hz a.c) and a maximum of 13Amps

      13 amp Plug


      C)ELECTRICAL SAFETY
      1. Fuses-
        A Fuse is a piece of wire designed to melt and break if too much current passes through it (e.g. a 3 amp fuse will "blow" if 3.5 amps is passed through it)
        Available for 3 pin plugs in the following sizes: 1 amp 3 Amps 5 Amps 10Amps 13Ampsfuses
      2. Earth Wire
        The Earth Wire provides a "safe route" for the Electricity to get to the ground
        Earthed cooker
        If the case is made out of metal and a wire touched the outside case a person touching the case would receive an electrical shock
        However, as you can see from this example (of an electric iron when something goes wrong inside, a large current flows through the live and out of the Earth wire. the Large current will blow th fuse and the Equipment will be safe NOTE equipment with a plastic case is said to be DOUBLE INSULATED and does not need an Earth wire
      3. Circuit Breakers
        circuit breaker
        There are two different kinds of circuit breakers: magnetic and thermal.
        Magnetic circuit breakers are by far more common The basic idea is that if current flows through the Earth wire there must be a problem. If that current flows through an electromagnet, a magnetic field will be produced. This will repel the metal switch which then disconnects the current to the live pin shutting off the electricity. The switch then locks in place until it is reset.

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    The Power rating of an appliance is related to how much it costs to use A High Powered appliance is most costly to use Electrical consumption is measured in kWh (kilowatt Hours) So Cost= kWh used × Unit price(p)
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