18/09/2015 p2 living for the future agac (ocr). 18/09/2015 wind power
TRANSCRIPT
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P2 Living for the FutureP2 Living for the Future
AGAC
(OCR)
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Wind PowerWind Power
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Solar EnergySolar Energy
Solar panels provide heating for homes – these pipes carry water that absorbs heat energy and transfers it to the house.
Solar cells – convert sunlight directly into electricity. Sunlight knocks electrons loose from the crystal structure and the loose electrons form an electric current. The amount of power depends on the area of the panel and the light intensity.
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Generating Generating ElectricityElectricity
The direction of the generated current is reversed if…
1) The magnet is moved in the opposite direction
2) The other pole is inserted first
The size of the generated current can be increased by:
1) Increasing the speed of movement
2) Increasing the magnet strength
3) Increasing the number of turns on the coil
19/04/23AC GeneratorAC Generator
Induced current can be increased in 4 ways:
1) Increasing the speed of movement
2) Increasing the magnetic field strength
3) Increasing the number of turns on the coil
4) Increasing the area of the coil
N S N S
Current
Time
19/04/23Using non-renewable fuels in power Using non-renewable fuels in power stationsstations
1) A fossil fuel is burned in the boiler
2) Water turns to steam and the steam drives a turbine
3) The turbine turns a generator
4) The output of the generator is connected to a transformer
5) The steam is cooled down in a cooling tower and reused
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FuelsFuelsA “fuel” is something that can be burned to release heat and light energy. The main examples are:
Coal, oil and gas are called “fossil fuels”. In other words, they were made from fossils.
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Nuclear power stationsNuclear power stationsThese work in a similar way to normal power stations:
The main difference is that the nuclear fuel is NOT burnt – it is used to boil water in a “heat
exchanger”
19/04/23The National GridThe National GridElectricity reaches our homes from power stations through the National Grid:
If electricity companies transmitted electricity at 230 volts through overhead power lines there would be too much ______ loss by the time electricity reaches our homes. This is because the current is ___. To overcome this they use devices called transformers to “step up” the voltage onto the power lines. They then “____ ____” the voltage at the end of the power lines before it reaches our homes. This way the voltage is _____ and the current and power loss are both ____.
Words – step down, high, power, low, high
Power stationStep up
transformerStep down
transformerHomes
powerhigh
step down
high low
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Efficiency of Power StationsEfficiency of Power Stations
100J Boiler 85J Turbine35J
Generator30J
15J 50J 5J
Heat
Heat Kinetic
Heat Heat
Electrical
The blue arrowsshow the energy wasted
The red arrows show the useful energy
This diagram shows that starting with 100 J only 30 J finishes up being useful as electrical energy
19/04/23EfficiencyEfficiencyEfficiency is a measure of how much USEFUL energy you get out of an object from the energy you put INTO it.For example, consider a TV:
Electrical Energy (200J)
Light (80J)
Sound (40J)
Heat (?)
Efficiency = Useful energy out
Energy in
x100%120 x100 =200
60%
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Some examples of efficiency…Some examples of efficiency…1) 500J of electrical energy are put into a motor. The
motor converts this into 100J of movement energy. How efficient is it?
2) A laptop can convert 400J of electrical energy into 200J of light and sound. What is its efficiency? Where does the rest of the energy go?
3) A power station is 50% efficient. If it delivers 20,000J of electrical energy how much chemical energy was put into it?
100/500
200/400
40,000J
x100 =20%
x100 =50%
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Some definitions…Some definitions…
A renewable energy source is clearly one that can be _______ (“renew = make again”), e.g. _____, solar power etc.
A ___________ energy source is one that when it has been used it is gone forever. The main examples are ____, oil and gas (which are called ______ ____, as they are made from fossils), and nuclear fuel, which is non-renewable but NOT a fossil fuel.
Words – non-renewable, coal, fossil fuels, wood, renewed
renewed wood
non-renewable
coal fossil fuels
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PollutionPollutionWhen a fuel is burned the two main waste products are _____ dioxide and ________ dioxide.
Carbon dioxide is a _________ ___ and helps cause ______ ______ This is produced when any fossil fuels are burned.
Sulphur dioxide, when dissolved in _______. causes ___ ___. This is mainly a problem for ____ power stations.
Nuclear power stations do not produce these pollutants because they don’t ____ fossil fuels.
Words – sulphur, coal, global warming, carbon, acid rain, greenhouse gas,
rainwater, burn
carbonsulphur
greenhouse gaswarming
rainwater acid raincoal
burn
global
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Non-renewable energy sourcesNon-renewable energy sources
Coal, oil, gas and nuclear
Advantages Disadvantages
Cheap fuel costs
Short start-up time for gas and oil
Good for “basic demand”
Fuel will run out
Costs a lot of money to
decommission a nuclear plant
Pollution – CO2 leads to global warming and SO2 leads to acid rain
Reliable
Nuclear produces little pollution
19/04/23Renewable energy sources Renewable energy sources summarysummary
Wind, tidal, hydroelectric and solar
Advantages Disadvantages
Zero fuel costs
Hydroelectric is good for a
“sudden” demand
Don’t produce pollution
Ugly and the energy produced by them is very
“dilute”
Unreliable (except for
hydroelectric)
Expensive to build
Solar is good for remote locations (e.g. satellites)
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The Cost of ElectricityThe Cost of ElectricityElectricity is measured in units called “kilowatt hours” (kWh). For example…
A 3kW fire left on for 1 hour uses 3kWh of energy
A 1kW toaster left on for 2 hours uses 2kWh
A 0.5kW hoover left on for 4 hours uses __kWh
A 200W TV left on for 5 hours uses __kWh
A 2kW kettle left on for 30 minutes uses __kWh
2
1
1
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The Cost of ElectricityThe Cost of ElectricityTo work out how much a device costs we do the following:Cost of electricity = Power (kW) x time (h) x cost per kWh (p)For example, if electricity costs 8p per unit calculate the cost of the following…
1) A 2kW fire left on for 3 hours
2) A 0.2kW TV left on for 5 hours
3) A 0.1kW light bulb left on for 10 hours
4) A 0.5kW hoover left on for 1 hour
48p
8p
8p
4p
During the night electricity companies reduce the cost of electricity to around 3p per unit. How much do these appliances cost to run overnight?
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PowerPower
Power is “the rate of doing work”. The amount of power being used in an electrical circuit is given by:
P
IVPower = voltage x current
in W in V in A
1) A 100W bulb runs on a voltage of 25V. What current does it draw?
2) A smaller bulb is powered by a 3V battery with a current of 2A. What is the power rating of this bulb?
3) A 2000W kettle is plugged into a 250V supply. What current does it draw?
4A
6W
8A
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The structure of the atomThe structure of the atomELECTRON –
negative, mass nearly
nothing
PROTON – positive,
same mass as neutron
(“1”)
NEUTRON – neutral,
same mass as proton
(“1”)
19/04/23Introduction to Introduction to RadioactivityRadioactivity
Some substances are classed as “radioactive” – this means that they are unstable and continuously give out radiation:
Radiation
The nucleus is more stable after emitting some radiation – this is called “radioactice decay”.
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Background RadiationBackground Radiation
Radon gas
Food
Cosmic rays
Gamma rays
Medical
Nuclear power
13% are man-made
19/04/23Types of radiationTypes of radiation1) Alpha () – an atom decays into a new atom and emits an alpha particle (2 protons and 2 ______ – the nucleus of a ______ atom)
2) Beta () – an atom decays into a new atom by changing a neutron into a _______ and electron. The fast moving, high energy electron is called a _____ particle.
3) Gamma – after or decay surplus ______ is sometimes emitted. This is called gamma radiation and has a very high ______ with short wavelength. The atom is not changed.
Unstable nucleus
Unstable nucleus
Unstable nucleus
New nucleus
New nucleus
New nucleus
Alpha particle
Beta particle
Gamma radiation
Words – frequency, proton, energy, neutrons, helium, beta
neutronshelium
protonbeta
energy
frequency
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Blocking RadiationBlocking RadiationEach type of radiation can be blocked by different materials:
Sheet of paper
Few mm of aluminium
Few cm of lead
19/04/23Handling Radioactive Handling Radioactive MaterialsMaterials
Safety measures:
1) Keep your distance
2) Minimise exposure time
3) Protective clothing
4) Careful labelling
19/04/23Disposing of radioactive Disposing of radioactive wastewaste
High level waste is immobilised by mixing with ____ making ingredients, melting and pouring the glass into steel containers.
Intermediate waste is set in cement in _____ drums.
The key to dealing with radioactive waste is to IMMOBILISE it. There are a number of ways of doing this depending on how __________ the waste is:
The containers are then kept in stores, often _________.
Words – glass, steel, underground, radioactive
radioactive
glass
steel
underground
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IonisationIonisationRadiation is dangerous because it “ionises” atoms – in other words, it turns them into ions by “knocking off” electrons:
Alpha radiation is the most ionising (basically, because it’s the biggest). Ionisation causes cells in living tissue to mutate, usually causing cancer.
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Uses of Alpha RadiationUses of Alpha RadiationSmoke detectors
Alarm
+ve electrode -ve
electrode
Alpha emitter
Ionised air particlesIf smoke enters here a current no longer flows
This sets off an alarm
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Uses of Beta RadiationUses of Beta Radiation
Rollers
Beta emitter
Beta detector
Paper
This is used to make sure the paper/steel is the correct thickness. The pressure on the rollers is adjusted depending on how much of the beta is received by the detector
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Uses of Gamma RadiationUses of Gamma RadiationSterilising medical instruments
Gamma rays can be used to kill and sterilise germs without the need for heating.
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Other uses of radioactivityOther uses of radioactivity1) Medical uses – gamma rays can be used to destroy cancerous cells
2) Tracers – a tracer is a small amount of radioactive material used to detect things, e.g. a leak in a pipe:
Gamma source
Tracers can also be used to develop better plant fertilisers and in medicine to detect tumours:
The radiation from the radioactive source is picked up above the ground, enabling the leak in the pipe to be detected.
19/04/23Comparing magnets and Comparing magnets and solenoidssolenoids
N SMagnet:
Solenoid:
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The Earth’s Magnetic FieldThe Earth’s Magnetic Field
This magnetic field gives us protection from ionising cosmic
rays
see the next two slides
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Solar FlaresSolar Flares
Solar flares are clouds of charged particles ejected at high speed from the sun. They can produce strong magnetic fields that interfere with satellites.
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Aurora BorealisAurora Borealis
19/04/23Our Solar SystemOur Solar System
Mercury
MarsJupiter
Saturn
Neptune
Uranus
Pluto
VenusEarth
My Very Easy Method Just Speeds Up Naming
Planets
19/04/23Solar systems, galaxies and the Solar systems, galaxies and the UniverseUniverse
OUR SUN is one of millions of stars that orbit the centre of…
THE MILKY WAY, which is one of a billion galaxies that orbit AND move away from the centre of…
THE UNIVERSE
(Basically, everything in the universe orbits around something else)
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Elliptical OrbitsElliptical Orbits
Ellipse
19/04/23The Earth is kept in orbit by 2 things…The Earth is kept in orbit by 2 things…
GravityGravity
…and by the fact that it is moving at a high velocity
This is called a “centripetal force”
19/04/23CometsCometsComets are balls of dust and frozen gas. They have very elliptical orbits:
As the comet approaches the sun gases evaporate from it, forming a “tail”. This tail always faces AWAY from the sun. The comet also goes faster near the sun.
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AsteroidsAsteroids
1) If an asteroid hit the Earth what effect would it have?
2) Many asteroids have already hit the Earth over many years – how do we know?
crater; ejection of hot rocks; widespread fires; sunlight blocked by dust; climate change; species extinction.
craters/unusual elements
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Space TravelSpace Travel
Manned space travel
Unmanned space travel
Advantages Disadvantages
Explain that manned spacecraft need to take food, water and oxygen.
unmanned spacecraft (probes) do not
need food, water or oxygen.
enough fuel; long time required; effect of low gravity on health; shielding from cosmic rays; maintaining a stable atmosphere; providing enough food and water; keeping warm.
unmanned spacecraft can withstand conditions that are lethal to humans. State that unmanned spacecraft can send back information on: temperature, magnetic field and radiation; gravity, atmosphere and surroundings
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Near Earth ObjectsNear Earth ObjectsA Near Earth Object (NEO) is an asteroid or comet on a possible collision course with the Earth.
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Evidence about the Evidence about the origins of the universe…origins of the universe…
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Evidence #1 - MicrowavesEvidence #1 - MicrowavesWhen the “Big Bang” happened microwaves were produced and these are still reaching us now. They can sometimes be seen as TV interference.
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Source of light “Spectra
”
Evidence #2 - RedshiftEvidence #2 - Redshift
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If you pass the light through a gas something different is seen…
helium
Some wavelengths of light are absorbed by
the gas – an “absorption spectrum”.
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After
helium
If the light source is moving away the absorption spectra look a little different…
helium
Before
19/04/23The absorption lines have all been “shifted” towards the longer wavelength end (red end)…
After
BeforeThis is called red
shift. The faster the light source moves the further its light will be “shifted”
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Light from different stars and from the edge of the universe also shows this “red-shift”. This suggests that everything in the universe is moving away from a single point.
This is the BIG BANG theory
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Red shift summaryRed shift summaryLight from other galaxies has a longer _________ than expected. This shows that these galaxies are moving ____ from us very quickly. This effect is seen to a greater extent in galaxies that are _______ away from us. This indicates that the further away the galaxy is, the ______ it is moving.
This evidence seems to suggest that everything in the universe is moving away from a single point, and that this process started around 15 _____ years ago. This is the ____ ____ Theory.
Words to use – faster, away, big bang, billion, wavelength, further
wavelengthaway
furtherfaster
billionbig bang
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The Life and Death of a StarThe Life and Death of a Star
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NebulaeNebulae
A nebulae is a collection of dust, gas and rock.
Some examples of nebulae…
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Dark nebula
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Emission nebula
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Planetary nebula
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Reflection nebula
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Gravity will slowly pull these particles together…
As they move inwards their gravitational potential energy is converted into heat and a PROTOSTAR is formed
ProtostarProtostar
19/04/23Main SequenceMain Sequence
Our sun is an example of a main sequence star – it’s in the middle of a 10 billion year life
span
In a main sequence star the forces of attraction pulling the particles inwards are _________ by forces acting outwards due to the huge __________ inside the star.
Stars are basically ________ reactors that use _______ as a fuel. During its main sequence a star will release energy by converting hydrogen and helium (light elements) into _________ elements.
Words – heavier, balanced, hydrogen, nuclear, temperatures
balanced
temperatures
nuclear hydrogen
heavier
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Eventually the fuels will run out. When this happens the star will become colder and redder and start to swell…
If the star is relatively small (like our sun – a
“medium weight star”) the star will become a RED
GIANT
If the star is big (at least 4 times the size of our sun – a “heavy weight star”) it will
become a RED SUPERGIANT
Red GiantsRed Giants
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What happens next depends on the size of the star…
1) For medium weight stars the red giant will collapse under its own gravity and form a very dense white dwarf:
The DeathThe Death
White dwarf
Red giant Planetary Nebula
19/04/232) Heavy weight stars will shrink and then EXPLODE, releasing massive amounts of energy, dust and gas.
AfterBefore
This explosion is called a
SUPERNOVA
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The dust and gas on the outside of the supernova are thrown away by the explosion and the remaining core turns into a NEUTRON STAR.
If the star was big enough (i.e. ten times heavier than our sun) it could become a BLACK HOLE.
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Detecting black holesDetecting black holesBlack holes can’t be detected directly, but their effects on other bodies can be observed.
This is a binary system. The black hole sucks in
material from its companion star. The
material becomes very hot and emits X-rays as
it falls into the black hole.