# Module P1- Energy for the home(Part 1)

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• Created by: Kimberley
• Created on: 16-04-14 10:48
• 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
• 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
• 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
• 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