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waves and energy

Waves and energy
1. Radiowaves
  1. Used for TV, phone, radio signals
  2. Lower frequencies than microwaves
  3. Longer wavelength than microwaves
  4. Frequencies range: 300,000Hz to 3000 million Hz
  5. Long wavelengths can diffract around hills, into tunnels
  6. The shorter the wavelength; the more info the carry, the shorter their range and the less they spread out
2. Microwaves
  1. Longitudinal
  2. Lower frequencies than visible light
  3. Longer wavelengths than visible light
  4. Diffract less than radiowaves
  5. Called 'Micro'waves as shorter wavelength than radiowaves
  6. Between infrared and radio in electromagnetic spectrum
  7. Used for communications and to transmit signals
3. X-radiation
  1. Used to take photos of bones- check for fractures
  2. Absorbed more by teeth and bone than soft tissue
  3. Lower frequency than Gamma
  4. Ionises subastances it passes through
  5. High doses kill cells
  6. Low doses cause cancer growth
  7. Organ consisting soft tissue-filled with contrast medium- absorbs X-ray easily
4. Gamma rays
  1. Used to sterilize surgical equipment, kill bacteria, kill cancer cells
  2. High frequency
  3. Cannot be seen/felt
  4. Mostly passes through skin/soft tissue but some absorbed by cells
5. Infrared
  1. Light shiny surfaces reflect radiation falling on them
  2. Hotter object emit more
  3. Dark, matt surfaces absorb it
  4. All objects emit it
  5. Absorbed by skin, damages/kills cells as heats them up
  6. Infrared devices:Optical fibres, Remote control headsets, infrared scanners, heaters
6. Types of Heat transfer
  1. Cavity wall insulation
  2. Loft insulation
  3. Draught proofing
  4. Convection
  5. Conduction
  6. Convection
  7. Radiation
7. Biofuel
  1. Made from plants and waste
  2. Advantages
    1. Reliable
    2. Creates jobs
    3. Quick to obtain
    4. Carbon neutral
    5. Renewable
  3. Disadvantages
    1. Cost of fuel
    2. Loss of food crops
    3. Deforestation-burning increases CO2
  4. Generate electricity same way as fossil fuels
Renewable energy sources
1. Wind power
2. Solar power
3. Hydroelectric
4. Wave
5. Tidal
6. Geothermal
7. Biofuel
8. Less effect on on environment than fossil fuels
Non-renewable energy sources
1. Fossil fuels
2. Acid rain
3. Extraction damages environment
  1. Affects habitats
  2. Release co2, increases green house effect
Nuclear energy sources
1. No greenhouse gases
2. DIsposal of waste
3. Consequence of accidents
Types of stored energy
1. Electrical
2. Light
3. Kinetic
4. Electrical
5. Chemical
6. Gravitational and elastic potenitals
Redshift
1. When objects move away from us- waves are spread out to longer wavelength
2. Light from other galaxies are redshifted
3. The further away a planet, the greater the redshift
4. Light from distant galaxies- see same pattern but at lower frequencies- shifted towards red end of spectrum
Energy transfer
1. Methods
  1. Conduction
  2. Convection
  3. Radiation
2. The bigger the temperature difference between an object and its surrounding, the faster the rate of energy transferred by heating
3. Rate transfer depends on; surface area, surfaces, material and volume
Waves
1. Transverse waves perpendicular(90 degrees) to direction of energy transfer
  1. Light and all other EMs waves, water
2. Longitudinal waves vibrations parallel to direction of energy transfer
  1. Compression and rarefaction
  2. Sound/ultrasound
Doppler effect
1. Change of frequency of wave when a source moves towards an observer
2. Longitudinal and transverse waves
3. Frequency of source moving towards you- seem higher and wavelength seem shorter
4. Frequency of source moving towards you- seem lower and wavelength seem longer
Waves and energy transfer
1. Evaporation
  1. Gain kinetic energy
  2. Average KE of particles left in liquid is lower, so the liquid is cooler
  3. increasing the rate depends
    1. Increasing temperature of gas
    2. Increasing surface area
    3. Decreasing density of gas
    4. High airflow
2. Blueshift
  1. Shift in frequency of photon towards higher energy and shorter wavelength
3. National grid
  1. Supply and demand is increasing
  2. National grid is electricity distribution network for uk
  3. Power can be generated anywhere on grid
  4. distribution- pylons or underground
    1. Pylons cheaper, ugly, easy to repair, affected by weather,less reliable
  5. Need high voltage/torrent
  6. Use transformers to get high voltage for grid-step up transformer
  7. Use transformers to get some voltage for home-step down transformer
4. Electricity and waves
  1. Non-renewable
    1. uranium
    2. pluntoium
    3. coal
    4. oil
    5. natural gas
    6. It will run out
    7. Damage environment
    8. Provide most energy
  2. Renewable
    1. Wind
      1. Wave
    2. Will never run out
    3. Doesn't damage environment
    4. Provide small amounts of energy
5. Solar power
  1. Advantages
    1. No pollution
    2. Used in remote places
    3. No environmental damage
    4. Almost no running costs
  2. Disadvantages
    1. Solar cells expensive
    2. Only generate small amounts of electricity
    3. Unreliable source of energy unless sunny country
6. Wave power
  1. Advantages
    1. good in remote island areas
    2. renewable
    3. No pollution
    4. Minimal running costs
  2. disadvantages
    1. high start up costs
    2. visual impact
    3. unreliable
  3. NOT same as tidal
  4. Water drives turbine, turbine drives generator
7. Convection
  1. Liquids and gases only
  2. All about changes in density
  3. Hotter particles with me kinetic energy move from hotter to colder region-taking their energy with them
8. Specific heat capacity
  1. Tells you how much energy materials can store
  2. Energy=mass x specific heat capacity x temperature change
  3. Takes more heat energy to increase temperature of some materials compared to others. These materials also release more energy as they cool-act as heat stores
  4. The amount of energy needed to raise temperature of 1kg of the substance by 1 degree
9. Energy effienciency
  1. Effectiveness-What gives you the most money every year
  2. Cost effectiveness-What has a shorter payback time
    1. Payback time-How long it takes for money you have saved on bills to equal the cost of putting in insulation
  3. U-volume- shows how fast heat is transferred through a material. The better the insulator, the lower the U-volume
10. Efficiency of machines
  1. Efficiency = useful energy divided by total energy/power in
  2. Energy not transferred usefully from form to another is dissipated- it usually heats surroundings and difficult to collect in or use
  3. Have to consider cost-effectiveness when choosing appliances
  4. Low energy bulb- 4x as efficient as ordinary bulb, last longer but cost more
  5. LED bulbs-more efficient than ordinary,last longer but cost more and dont give out much light
11. Wind power
  1. advantages
    1. no pollution
    2. no permanent damage to landscape
    3. minimal running cost
    4. renewable
  2. Disadvantages
    1. noisy
    2. high start costs
    3. need a lot of them and a lot of space
    4. unreliable
  3. turbine gets turned by wind, turbine drives generator
12. conduction in metal strips
  1. when heated at one end, heat travels to other end
  2. as heated-particles vibrate-these vibrations make the adjacent particles vibrate. vibration and heat passed along metal
13. conduction in solids
  1. metals good conductors and have free electrons (free to move) in the metal
  2. poor conductors have larger spaces between particles or are insulators
  3. vibrating particles- pass on their extra kinetic energy to their neighbours by colliding with them-this is faster in dense solids
14. steady state theory
  1. big problems with this theory
  2. universe existed as it is now and it always will do
  3. based on idea the universe looks the same pretty much everywhere
  4. explains expansion by suggesting matter being created in spaces as universe expnds
15. big bang theory
  1. estimated to have happened 14 billion years ago
  2. Thinks all matter and energy was compressed then exploded
  3. can use current rate of expansion to estimate age
  4. doesnt explain condtions or what caused the explosion
16. hydroelectric
  1. advantages
    1. renewable
    2. peak demand
    3. reliable if no draught
    4. no pollution
    5. cheap to run
  2. disadvantages
    1. high start up cost
    2. people can lose homes
    3. destroys habitats
    4. rotting vegetation release methane and co2
  3. pumped storage-pump water back up
17. tidal power
  1. advantages
    1. renewable
    2. good for storing energy for peak demand
    3. quite reliable
    4. minimal running costs
  2. disadvantages
    1. high start up costs
    2. energy will vary-height of tide will vary
  3. sun and moon's gravity moves water, drives turbine, turbine drives generator
  4. the source of energy=gravitational force of moon and sun
18. comparing energy sources
  1. renewable-have lowest running fuel costs
  2. renewable often weather dependent
  3. non-renewable more reliable
  4. renewables need bigger power stations-costs more
19. geothermal energy
  1. advantages
    1. reliable
    2. minimal running costs
    3. renewable
  2. disadvantages
    1. high start up costs
    2. limited number of possible locations
  3. can only happen where earth's crust is thin
20. dam
  1. built across a valley, causing it to flood
  2. water falls through dam, gravitational energy of this water converts to kinetic
  3. kinetic of water is used to turn a turbine and generate electricity
21. sankey diagrams
  1. thickness of line represents amount of energy
  2. can be drawn to scale so width of each arrow is proportional the amount of energy

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	Created by laurensibthorp almost 9 years ago