Download Nuclear power stations

22/05/2017
P2 Living for the Future
(OCR)
AGAC
Wind Power
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Solar Energy
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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.
Solar panels provide heating for
homes – these pipes carry water
that absorbs heat energy and
transfers it to the house.
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Generating
Electricity
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
AC Generator
N
S
N
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S
Current
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
Time
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Using non-renewable fuels in power stations
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
Fuels
22/05/2017
A “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.
Nuclear power stations
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These 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”
The National Grid
22/05/2017
Electricity reaches our homes from power stations through the National
Grid:
Power station
Step up
transformer
Step down
transformer
Homes
If electricity companies transmitted electricity at 230 volts through
power loss by the time
overhead power lines there would be too much ______
electricity reaches our homes. This is because the current is high
___. To
overcome this they use devices called transformers to “step up” the
step down
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 _____
high and the current and power loss are both ____.
low
Words – step down, high, power, low, high
Efficiency of Power Stations
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The blue arrows
show the energy wasted
Heat
100J
Boiler
85J
Heat
The red arrows
show the useful energy
Heat
Turbine
35J
Kinetic
Heat
Generator
30J
Electrical
This diagram shows that starting with 100 J
only 30 J finishes up being useful as electrical energy
Efficiency
22/05/2017
Efficiency 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)
Sound (40J)
Efficiency = Useful energy out
Energy in
x100%
120
200
x100 =
60%
Some examples of efficiency…
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1) 500J of electrical energy are put into a motor. The motor
converts this into 100J of movement energy. How
efficient is it?
100/500
x100
=20%
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?
200/400
x100
=50%
3) A power station is 50% efficient. If it delivers 20,000J of
electrical energy how much chemical energy was put into it?
40,000J
Some definitions…
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A renewable energy source is clearly one that can be
renewed (“renew = make again”), e.g. _____,
wood solar power
_______
etc.
A ___________
non-renewable energy source is one that when it has
been used it is gone forever. The main examples are
coal oil and gas (which are called ______
fossil fuels
____,
____, as they
are made from fossils), and nuclear fuel, which is nonrenewable but NOT a fossil fuel.
Words – non-renewable, coal, fossil
fuels, wood, renewed
Pollution
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When a fuel is burned the two main waste products are _____
carbon
sulphur dioxide.
dioxide and ________
global
Carbon dioxide is a _________
greenhouse ___
gas and helps cause ______
______ This is produced when any fossil fuels are burned.
warming
rainwater causes ___
Sulphur dioxide, when dissolved in _______.
___.
acid rain
coal power stations.
This is mainly a problem for ____
Nuclear power stations do not produce these pollutants
burn fossil fuels.
because they don’t ____
Words – sulphur, coal, global warming, carbon,
acid rain, greenhouse gas, rainwater, burn
Non-renewable energy sources
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Advantages
Disadvantages
Cheap fuel costs
Costs a lot of
money to
decommission a
nuclear plant
Good for “basic
demand”
Reliable
Coal, oil, gas and
nuclear
Fuel will run
out
Short start-up time for
gas and oil
Nuclear produces little
pollution
Pollution – CO2 leads to
global warming and SO2
leads to acid rain
Renewable energy sources summary
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Advantages
Disadvantages
Zero fuel costs
Unreliable
(except for
hydroelectric)
Don’t produce
pollution
Hydroelectric
is good for a
“sudden”
demand
Solar is good for
remote locations
(e.g. satellites)
Wind, tidal,
hydroelectric and solar
Expensive
to build
Ugly and the energy
produced by them is very
“dilute”
The Cost of Electricity
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Electricity 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
2
1
A 200W TV left on for 5 hours uses __kWh
A 2kW kettle left on for 30 minutes uses __kWh
1
The Cost of Electricity
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To 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
48p
2) A 0.2kW TV left on for 5 hours
8p
3) A 0.1kW light bulb left on for 10 hours
8p
4) A 0.5kW hoover left on for 1 hour
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?
Power
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Power is “the rate of doing work”.
The amount of power being used in
an electrical circuit is given by:
Power = voltage x current
in W
in V
in A
P
V
I
1) A 100W bulb runs on a voltage of 25V. What current does
4A
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? 6W
3) A 2000W kettle is plugged into a 250V supply. What
8A
current does it draw?
The structure of the atom
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ELECTRON –
negative, mass
nearly nothing
NEUTRON –
neutral, same
mass as
proton (“1”)
PROTON –
positive, same
mass as
neutron (“1”)
Introduction to Radioactivity
22/05/2017
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”.
Background Radiation
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13% are
man-made
Radon gas
Food
Cosmic rays
Gamma rays
Medical
Nuclear power
Types of radiation
Unstable
nucleus
New
nucleus
Alpha
particle
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1) Alpha () – an atom decays into a new
atom and emits an alpha particle (2
protons and 2 ______
neutrons – the nucleus of a
helium atom)
______
2) Beta () – an atom decays into a new
atom by changing a neutron into a
_______
proton and electron. The fast moving,
beta
Beta high energy electron is called a _____
particle particle.
Unstable
nucleus
New
nucleus
Unstable
nucleus
New
nucleus
3) Gamma – after  or  decay surplus
______
energy is sometimes emitted. This is
called gamma radiation and has a very
highfrequency
______ with short wavelength.
The atom is not changed.
Gamma
radiation
Words – frequency, proton,
energy, neutrons, helium, beta
Blocking Radiation
22/05/2017
Each type of radiation can be blocked by different materials:



Sheet of
paper
Few mm of
aluminium
Few cm of
lead
Handling Radioactive Materials
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Safety measures:
1) Keep your distance
2) Minimise exposure time
3) Protective clothing
4) Careful labelling
Disposing of radioactive waste
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The key to dealing with radioactive waste is
to IMMOBILISE it. There are a number of
ways of doing this depending on how
radioactive the waste is:
__________
High level waste is immobilised by mixing with
glass
____ making ingredients, melting and pouring
the glass into steel containers.
Intermediate waste is set in
steel drums.
cement in _____
The containers are then kept
underground
in stores, often _________.
Words – glass, steel, underground, radioactive
Ionisation
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Radiation 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.
Uses of Alpha Radiation
Smoke detectors
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Alpha
emitter
+ve electrode
-ve electrode
Alarm
Ionised air particles
This sets off an alarm
If smoke enters here a
current no longer flows
Uses of Beta Radiation
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Beta
detector
Rollers
Paper
Beta
emitter
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
Uses of Gamma Radiation
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Sterilising medical instruments
Gamma rays can be used to kill and sterilise
germs without the need for heating.
Other uses of radioactivity
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1) 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
The radiation from the radioactive source is picked up above
the ground, enabling the leak in the pipe to be detected.
Tracers can also be used to develop
better plant fertilisers and in
medicine to detect tumours:
Comparing magnets and solenoids
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Magnet:
Solenoid:
N
S
The Earth’s Magnetic Field
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This magnetic field gives us
protection from ionising cosmic rays
see the next
two slides
Solar 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 Borealis
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Our Solar System
Mercury
Venus
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Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto
My Very Easy Method Just
Speeds Up Naming Planets
Solar systems, galaxies and the Universe
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(Basically, everything in the universe orbits around something else)
OUR SUN is one of
millions of stars that
orbit the centre of…
THE UNIVERSE
THE MILKY WAY,
which is one of a billion
galaxies that orbit
AND move away from
the centre of…
Elliptical Orbits
Ellipse
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The Earth is kept in orbit by 2 things…
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This is called a
“centripetal force”
Gravity
…and by the
fact that it is
moving at a high
velocity
Comets
Comets 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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Asteroids
1) If an asteroid hit the Earth
what effect would it have?
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crater;
ejection of hot rocks; widespread fires;
sunlight blocked by dust; climate change;
species extinction.
2) Many asteroids have already hit
the Earth over many years –
craters/unusual elements
how do we know?
Space Travel
Advantages
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Disadvantages
Manned space
travel
unmanned spacecraft (probes) do not need
food, water or oxygen.
Unmanned space
unmanned spacecraft can withstand conditions thattravel
are lethal to humans.
State that unmanned spacecraft can send back
information on:
temperature, magnetic field and radiation;
gravity, atmosphere and surroundings
Explain that manned spacecraft need
to take food, water and 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.
Near Earth Objects
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A Near Earth Object (NEO) is an asteroid or comet on a
possible collision course with the Earth.
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Evidence about the origins of
the universe…
Evidence #1 - Microwaves
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When the “Big Bang” happened microwaves were produced and
these are still reaching us now. They can sometimes be seen
as TV interference.
Evidence #2 - Redshift
Source of
light
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“Spectra”
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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”.
If the light source is moving away the absorption
spectra look a little different…
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Before
helium
helium
After
The absorption lines have all been “shifted”
towards the longer wavelength end (red end)…
This is called red
shift. The faster
the light source
moves the further
its light will be
“shifted”
Before
After
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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
Red shift summary
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wavelength than
Light from other galaxies has a longer _________
away
expected. This shows that these galaxies are moving ____
from us very quickly. This effect is seen to a greater
further away from us. This
extent in galaxies that are _______
indicates that the further away the galaxy is, the ______
faster
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 _____
billion years ago. This is the
big ____
bang Theory.
____
Words to use – faster, away, big bang,
billion, wavelength, further
The Life and Death of a Star
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Nebulae
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
Protostar
Gravity will slowly pull these
particles together…
As they move inwards
their gravitational
potential energy is
converted into heat and
a PROTOSTAR is formed
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Main Sequence
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In a main sequence star the
forces of attraction pulling
the particles inwards are
balanced
_________
by forces acting
outwards due to the huge
temperatures
__________
inside the star.
nuclear
hydrogen
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)
heavier
into _________
elements.
Our sun is an example of a main sequence star –
it’s in the middle of a 10 billion year life span
Words – heavier, balanced, hydrogen, nuclear, temperatures
Red Giants
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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
The Death
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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:
Red giant
Planetary Nebula
White dwarf
2) Heavy weight stars will shrink
and then EXPLODE, releasing
massive amounts of energy, dust
and gas.
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This explosion is
called a
SUPERNOVA
Before
After
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.
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If the star was big
enough (i.e. ten times
heavier than our sun)
it could become a
BLACK HOLE.
Detecting black holes
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Black 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.