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