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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.

19/04/23

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.