Energy Transfer

pretty much everything you need to know on this topic for GCSE, includes some equations

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  • Energy Transfer
    • Particles
      • Solids
        • set shape
        • can't be compressed
        • joined by bonds
        • vibrations can pass through
      • Liquids
        • Can be poured
        • takes the shape of the container
        • can't be compressed
      • Gas
        • Not bonded
        • can be compressed
          • Why? - particles are so spread out so they can be compressed (squashed) together easily. While in solids and liquids the particles are more compact
    • Evaporation- when a liquid turns into a gas
      • Best  conditions for evaporation
        • big surface area
        • warm temperature
        • dry
        • windy
        • not humid
      • Our hands fell cold when using hand gel  because the gel takes the heat energy away from our hands
      • A liquid cools down when it evaporates because
        • 1. particles with the most energy evaporate
        • 2. they have enough energy to overcome the forces from other particles
        • 3. the average energy of the ones left behind decreases so the temperature decreases
    • Condensation- when a gas turns into a liquid
      • 1. gas cools so particles slow down ,lose kinetic energy and are pulled together
      • 2. as the temp drops the particles get close enough together that condensation occurs
    • Thermal Radiation/ Infa-red
      • Matt/ black surfaces
        • good absorbers
        • good emitters
      • Shiny/silver surfaces
        • good reflector
        • poor emitter
      • Using thermal Radiation
        • can travel through a vacuum
        • travels in straight lines
        • travels at the speed of light
        • matt surfaces are the best at emitting infa-red radiation
    • Convection
      • 1. particles gain energy, move apart and become less dense so they rise
      • 2. As the heated particles move away from the heat source, they cool,  become closer together and fall
    • Conduction
      • Solids are the best conductors because the particles are closer together
      • 1. particles closest to heat source begin to vibrate more, which passes on the energy to surrounding particles
      • 2. These surrounding particles also begin to vibrate faster until all particles are vibrating faster and the solid expands
      • Metals are good conductors because they have free electrons, which move where they want and pass on energy quicker
    • Payback time- cost divided by saving
    • Cost effective- total saving minus the initial cost
    • The lower the U value, the better insulator the material is
    • Specific Heat Capacity
      • E=M x C x 0
        • E= energy transferred in joules (J)
        • M= mass in kg
        • C= specific heat capacity in J/kg degrees C
        • 0= temperature change in degrees C
    • Heat Transfer
      • Cavity Wall
        • stops convection, radiation and conduction
      • Loft
        • stops conduction and radiation
      • Draught proofing
        • stops convection
      • curtains
        • conduction and radiation
    • Types of energy
      • electrical
        • whenever a current flows
      • light
        • sun, light bulbs
      • sound
        • noise
      • kinetic
        • movement
      • thermal
        • hot objects to cold
      • gravitational potential
        • anything that can fall
      • elastic potential
        • stretched springs, bands etc
      • chemical
        • foods and batteries

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