Module P1- Energy for the home(Part 1)

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  • Module P1- Energy for the home(Part 1)
    • Moving and Storing Heat
      • Heat
        • Measure of energy
      • Temperature
        • Measure of the average kinetic energy of the particles in a substance.
        • Measured in °C
      • Specific Heat Capacity
        • The amount of energy needed to raise the temperature of 1kg of a substance by 1°C.
        • Energy(j)= Mass(kg) x Specific Heat Capacity(j/kg/°C) x Temperature Change(°C)
      • Energy flows from hot objects to cooler ones
      • If there's a difference in temperature between two places, then energy will flow between them.
    • Melting and Boiling
      • Boiling
        • When you heat a liquid, the heat energy makes the particles move faster.
          • Eventually, when enough of the particles have enough energy to overcome their attraction to each other, big bubbles of  gas form in the liquid.
      • Melting
        • Heat energy makes the particles vibrate faster until eventually the forces between them are overcome and the particles start to move around.
      • When a substance is melting or boiling, the energy is used for breaking intermolecular bonds rather than raising the temperature.
      • When a substance is condensing or freezing, bonds are forming between particles, which release energy.
        • Temperature won't go down.
      • Specific Latent Heat
        • The amount of energy needed to change state
        • Energy(j) = Mass(kg) x Specific Latent Heat( j/kg)
    • Conduction
      • Occurs mainly in Solids
      • The process where vibrating particles pass on extra kinetic energy to neighboring particles
      • Metals are good conductors
        • Electrons move faster and collide with other free electrons, transferring energy inside the metal.
    • Convection
      • Occurs in Liquids and gases
      • The more energetic particles move from the hotter region to the cooler region and take their heat energy with them.
      • When you heat up a liquid or a gas, the particles move faster and expand to become less dense.
        • The warmer air rises above the cooler air
          • This process forms convection currents
    • Heat Radiation
      • All objects emit and absorb heat radiation
      • Cooler objects absorb the heat radiation emitted by hotter objects
        • Temperature increases
      • Dark Matt surfaces
        • Good absorbers and emitters of infrared radiation
      • Light coloured smooth and shiny objects
        • Poor absorbers and emitters of infrared radiation
          • Reflect heat radiation
      • It can travel in a vacuum
        • Heat reaches us from the sun
    • Saving Energy
      • Insulation
        • Loft Insulation
          • Fiberglass wool laid across the loft floor reduces conduction
        • Hot Water Tank Jacket
          • Reduces Conduction
        • Double Glazing
          • Two layers of glass with an air gap between reduce conduction
        • Cavity Walls
          • Twolayers of bricks with a gap between them reduce conduction
          • Insulation foam in the gap traps pockets of air to minimize convection.
        • Draught- proofing
          • Strips of foam and plastic around doors and windows stop hot air from escaping and reduces convection.
        • Thick Curtains
          • Reduce conduction and radiation through the window
      • Sources
        • Emit energy
        • E.g radiators
      • Sinks
        • Lose energy
        • E.g windows and computers
      • Payback Time= Initial Cost / Annual Saving
      • Thermograms
        • Shows where you are wasting energy in different areas.
          • White, yellow and red
            • Losing energy
          • Black, dark blue and purple
            • Not losing energy
    • Efficiency
      • Efficiency=(Useful Energy Output/ Total Energy Input) x 100%
    • Wave Basics
      • Amplitude is the displacement from the rest position to the crest
      • The wavelength is the length of a full cycle of the wave
      • Frequency is the number of complete cycles.
        • Measured in hertz(Hz)
      • Reflection
        • Angle of Incidence= Angle of Reflection
      • Total Internal reflection
        • Angle of incidence is greater than the critical angle
        • When the ray of light enters a less dense medium it will bend away from the normal
      • Diffraction
        • Waves spread out when they pass through a gap or pass an object
        • The narrower the gap, the more the wave spreads out.
      • Refraction
        • When a ray of light enters a more dense medium it will bend towards the normal
        • When a ray of light enters a less dense medium it will bend away from the normal

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