Living for the Future

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Living for the Future
(OCR)
W Richards The Weald School
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Wind Power
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Solar Energy
Photocells 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.
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
• The magnet is moved in the opposite direction
• The other pole is inserted first

• The size of the generated current can be
  increased by
• Increasing the speed of movement
• Increasing the magnet strength
• Increasing the number of turns on the coil

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AC Generator
N
S
N
S
Current

• Induced current can be increased in 4 ways
• Increasing the speed of movement
• Increasing the magnetic field strength
• Increasing the number of turns on the coil
• 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
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Fuels
A fuel is something that can be burned to
release heat and light energy. The main examples
are
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Nuclear power stations
These work in a similar way to normal power
stations
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The National Grid
Electricity reaches our homes from power stations
through the National Grid
If electricity companies transmitted electricity
at 240 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
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Efficiency of Power Stations
Heat
Heat
Heat
15J
Boiler
Turbine
Generator
100J
50J
5J
85J
35J
30J
Heat
Kinetic
Electrical
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Efficiency
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
Light (80J)
Electrical Energy (200J)
Sound (40J)
Heat (?)
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Some examples of efficiency

1. 5000J 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 240J 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?

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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
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Pollution
When 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 dont ____ fossil
fuels.
Words sulphur, coal, global warming, carbon,
acid rain, greenhouse gas, rainwater, burn
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Non-renewable energy sources
Advantages
Disadvantages
Cheap fuel costs
Costs a lot of money to decommission a nuclear
plant
Good for basic demand
Reliable
Fuel will run out
Short start-up time for gas and oil
Pollution CO2 leads to global warming and SO2
leads to acid rain
Nuclear produces little pollution
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Renewable energy sources summary
Advantages
Disadvantages
Zero fuel costs
Unreliable (except for hydroelectric)
Dont produce pollution
Expensive to build
Hydroelectric is good for a sudden demand
Ugly and the energy produced by them is very
dilute
Solar is good for remote locations (e.g.
satellites)
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The Cost of Electricity
Electricity is measured in units called kilowatt
hours (kWh). For example
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The Cost of Electricity
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
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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Power
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

1. A 100W bulb runs on a voltage of 240V. What
   current does it draw?
2. A smaller bulb is powered by a 3V battery with a
   current of 0.2A. What is the power rating of
   this bulb?
3. A 2000W kettle is plugged into a 240V supply.
   What current does it draw?

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The structure of the atom
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Introduction to Radioactivity
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 Radiation
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Types of radiation
1) Alpha (?) an atom decays into a new atom
and emits an alpha particle (2 protons and 2
______ the nucleus of a ______ atom)
Unstable nucleus
New nucleus
Alpha particle
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.
Beta particle
Unstable nucleus
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.
Words frequency, proton, energy, neutrons,
helium, beta
Unstable nucleus
New nucleus
Gamma radiation
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Blocking Radiation
Each type of radiation can be blocked by
different materials
Sheet of paper
Few mm of aluminium
Few cm of lead
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Handling Radioactive Materials
Safety measures

1. Keep your distance
2. Minimise exposure time
3. Protective clothing
4. Careful labelling

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Disposing of radioactive waste
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
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.
Words glass, steel, underground, radioactive
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Ionisation
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 its the biggest). Ionisation causes
cells in living tissue to mutate, usually causing
cancer.
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Uses of Alpha Radiation
Smoke detectors
Alarm
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Uses of Beta Radiation
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Uses of Gamma Radiation
Sterilising medical instruments
Gamma rays can be used to kill and sterilise
germs without the need for heating.
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Other uses of radioactivity
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
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
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Comparing magnets and solenoids
Magnet
Solenoid
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The Earths Magnetic Field
This magnetic field gives us protection from
ionising cosmic rays
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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
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto
My Very Easy Method Just Speeds Up Naming Planets
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Solar systems, galaxies and the Universe
(Basically, everything in the universe orbits
around something else)
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
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Elliptical Orbits
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The Earth is kept in orbit by 2 things
Gravity
and by the fact that it is moving at a high
velocity
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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?
2. Many asteroids have already hit the Earth over
   many years how do we know?

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Space Travel
Advantages
Disadvantages
Manned space travel
Unmanned space travel
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Near Earth Objects
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
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Evidence 1 - Microwaves
When 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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Evidence 2 - Redshift
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If you pass the light through a gas something
different is seen
Some wavelengths of light are absorbed by the gas
an absorption spectrum.
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If the light source is moving away the absorption
spectra look a little different
helium
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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
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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.
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Red shift summary
Light 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
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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
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Protostar
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Main Sequence
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Red Giants
Eventually the fuels will run out. When this
happens the star will become colder and redder
and start to swell
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The Death
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
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2) Heavy weight stars will shrink and then
EXPLODE, releasing massive amounts of energy,
dust and gas.
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 holes
Black holes cant 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.