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Infrared Radiation: Dark, matt surfaces absorb and emit well. Light, shiny surfaces reflect well.
Evaporation: factors Condensation: factors
Heat Transfer: Surface area/volume, material the object is madefrom, temp of surroundings.
U-Value: How effective the insulator is. The lower the better.
E=MXCX E = Energy = J M = Mass = Kg = Temp Change = °C C = Specific HC = J/kg
Wasted Energy: Transferred to surroundings, which warms up. The wasted energy dissipates.
Energy Transfers: Time the appliance is switchedon and power. Efficiency = Decimal/Percent.
E=PXT E = Energy Transferred = kWh or J P = Power = kWor W T = Time = h or s
Power Stations: Energy source is used to heat water. The steam produced drives a turbine that is coupled to
an electrical generator. Energy sources include: fossil fuels, uranium and plutonium, biofuels, wind and HEP
Solar Cells: Advantages and Disadvantages
Geothermal energy: Hot water and steam rise to the surface. The steam is used to drive turbines.
Small Scale: Expensiveto connect to National Grid, but useful. E.g. Solar cells for roadside signs.
Negative Effects: gases released, waste materials, noise and visual pollution, destroyed habitats
Carbon Capture: Catch and store CO2. Natural containers = oil and gas fields. UnderNorth Sea.
National Grid: Electricity is distributed from power stations to consumers along National Grid.
Transformers: Increased voltage reduces the current required, reducing energy losses in cables.
Waves: Transfer energy.Electromagnetic = Travel through vacuum. Tranverse
Appearance: Longitudinal waves show areas of compression andrarefaction.
Uses: Radio waves - television, and radio (diffraction)M icrowaves mobile phones and satellite television.
Infrared remote controls . Visible light photography.
Diagrams: Waves are not refracted if travelling along the normal. Waves can be reflected, refracted and
diffracted.Waves undergo a change of direction when they are refracted at an interface.
Reflection: The normal is a construction line perpendicular to the reflecting surface at the point of incidence.
Angle of incidence = Angle of reflection.
Image s in a plane mirror are virtual.
Sound: Sound waves are longitudinal and cause vibrations in a medium = Sound. The pitch of a sound =
frequency and loudness
=amplitude.Echoes are reflections of sounds.
Doppler Effect: If a wave source is moving relative to an observer there will be a change in the observed
wavelength and frequency. The wave source could be light, sound or microwaves . W hen the source moves
away,the observed wavelength increases and the
Big Bang Theory: The universe is expanding. Matter + space expanded from a tiny initial `point.'
Red-shift: There is an observed increase in the wavelength of light from most distant galaxies. The further
the galaxies, the faster they are moving, and thebigger the observed increase in wavelength.
Cosmic microwave background radiation (CMBR) : Electromagnetic radiation filling the universe. It comes
from radiation that was present shortly afterthe beginning of the universe.
The `Big Bang' theory is currently the only theory thatcan explain the existence of CMBR.
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Forces: Whenever two objects interact, the forces they exert on each other are equal and opposite.
Resultant force: Single force that has the same effect on the motion = A number of forces acting at a point.…read more
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Transformers: An alternating current in the primary coil produces a changing magnetic field in the iron core and
hence in the secondary coil. This induces an alternating potential difference across the ends of the secondary coil.
They have insulated wires and a laminated iron core.
Transformer equations: Potential Difference = Volts = V Current = Amperes = Amps
Switch Mode Transformers: operate between 50 kHz and 200 kHz. Very light and small.…read more