What is heat?
- heat is a form of energy
- measured in Joules(J)
- always flows from a higher temperature to a lower temperature
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What is temperature?
- degree of hotnes on an arbitrary or chosen scale
- measurement of the average kinetic energy of particles
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What is a thermogram?
- temperature can be represented by colours.
- the hottest parts are white/red/yellow
- the coldest parts are black/dark blue/purple
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What is the formula for specific heat capacity, an
- energy = mass(kg) x shc(J/KGdegC) x temp. change(degC)
- or e =mc^t
- tells you how much energy in joules you need to raise the temperature of 1kg of the material by 1degC
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What is the formula for specific latent heat capac
- energy=mass(kg) x specific latent heat (J/KG)
- or E=M L
- tells you how much energy is needed to boil or melt 1kg of a substance
- energy is needed to break the intermolecular forces during change of state
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What is CONDUCTION?
- conduction of heat is the process in which vibrating particles *** on extra kinetic energy to neighbouring particles
- kinetic energy is transferred between particles, vibrating particles pass on their extra energy to neighbouring particles
- metals are good conductors due to their free electrons moving and carrying energy with them
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Give 3 examples of good conductors.
- graphite (carbon)
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Give 6 examples of bad conductors.
- materials containing trapped air
- expanded polystyrene
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What is CONVECTION?
- convection ccurs when 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 gs, the particles move faster and the fluid is less dense. The warmer, less dense fluis rises above the coolder, denser surroundings
- s the arm fluid rises, cooler fluid takes its place.
- as this continues, you end up with a circulation (convection currents)
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What is RADIATON?
- infrared radiation is an electromagnetic wave, carrying energy and needs no medium to travel through. It is reflected by shiny surfaces and is absorbed by dull and rough surfaces
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Why do energy loss occur in houses?
- energy flows from the heat source (the house) to the cold surroundings (outside)
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Name 6 energy saving measures.
- loft insulation
- rock wool
- mineral wool
- double glazing
- cavity wall insulation
- curtains at windows
- reflective foil in/on walls
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What is the formula for efficiency? How can this b
- efficiency = useful energy output / total energy input
- (x100 for percentage)
- this can be shown on a SANKEY DIAGRAM
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What is the formula for finding out the payback ti
- tells you how cost effective different forms of insulation are.
- payback time = installation cost/ fuel save per year.
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What is REFLECTION?
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What is REFRACTION?
- this involes the change in direction of a wave due to passing from one medium to another (e.g. air to glass)
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What is DIFFRACTION?
- whenever waves pass through a gap or move around an obstacle, they spread out
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What is TOTAL INTERNAL REFLECTION?
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What is the CRITICAL ANGLE?
- when the refracted light emerges parallel to the block, the light is entering at the critical angle.
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Whats special about a laser?
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How do CD players read CDs using laser technology?
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What is the speed of light?
- 300,000,000 m/s
- 3 x 10^8 m/s
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Describe the electromagnetic spectrum.
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Describe the model of a transverse wave.
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What is the frequency?
- the frequency is the number of complete waves, circles, or oscillations per second
- measured in Hertz (Hz)
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What is the formula for the speed of a wave?
- wave speed(m/s) = frequency (Hz) x wavelength (m)
- v = f x lamda
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What is the relationship between the size of a rec
- 'the longer the wavelength the long the ariel needed to pick up the signal.'
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