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P2 Living for the Future

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Title: P2 Living for the Future


1
P2 Living for the Future
(OCR)
AGAC
2
Wind Power
3
Solar Energy
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.
4
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

5
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
6
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
7
Fuels
A fuel is something that can be burned to
release heat and light energy. The main examples
are
8
Nuclear power stations
These work in a similar way to normal power
stations
9
The National Grid
Electricity 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 ____.
power
high
step down
high
low
Words step down, high, power, low, high
10
Efficiency of Power Stations
The blue arrows show the energy wasted
The red arrows show the useful energy
Heat
Heat
Heat
15J
Boiler
Turbine
Generator
100J
50J
5J
85J
35J
30J
Heat
Kinetic
Electrical
This diagram shows that starting with 100 J only
30 J finishes up being useful as electrical energy
11
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 (?)
120 x100 200
60
12
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
x100
20
200/400
x100
50
40,000J
13
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.
renewed
wood
non-renewable
coal
fossil fuels
Words non-renewable, coal, fossil fuels, wood,
renewed
14
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.
carbon
sulphur
global
greenhouse gas
warming
rainwater
acid rain
coal
burn
Words sulphur, coal, global warming, carbon,
acid rain, greenhouse gas, rainwater, burn
15
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
16
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)
17
The Cost of Electricity
Electricity is measured in units called kilowatt
hours (kWh). For example
2
1
1
18
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?
19
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 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
20
The structure of the atom
21
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.
22
Background Radiation
23
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)
neutrons
Unstable nucleus
New nucleus
Alpha particle
helium
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.
proton
beta
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.
energy
frequency
Words frequency, proton, energy, neutrons,
helium, beta
Unstable nucleus
New nucleus
Gamma radiation
24
Blocking Radiation
Each type of radiation can be blocked by
different materials
Sheet of paper
Few mm of aluminium
Few cm of lead
25
Handling Radioactive Materials
Safety measures
  1. Keep your distance
  2. Minimise exposure time
  3. Protective clothing
  4. Careful labelling

26
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
radioactive
High level waste is immobilised by mixing with
____ making ingredients, melting and pouring the
glass into steel containers.
glass
Intermediate waste is set in cement in _____
drums.
steel
underground
Words glass, steel, underground, radioactive
27
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.
28
Uses of Alpha Radiation
Smoke detectors
Alarm
This sets off an alarm
29
Uses of Beta Radiation
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
30
Uses of Gamma Radiation
Sterilising medical instruments
Gamma rays can be used to kill and sterilise
germs without the need for heating.
31
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
32
Comparing magnets and solenoids
Magnet
Solenoid
33
The Earths Magnetic Field
This magnetic field gives us protection from
ionising cosmic rays
see the next two slides
34
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.
35
Aurora Borealis
36
Our Solar System
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Pluto
My Very Easy Method Just Speeds Up Naming Planets
37
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
38
Elliptical Orbits
39
The Earth is kept in orbit by 2 things
Gravity
and by the fact that it is moving at a high
velocity
40
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.
41
Asteroids
crater ejection of hot rocks widespread fires
sunlight blocked by dust climate change
species extinction.
  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?

craters/unusual elements
42
Space Travel
Advantages
Disadvantages
Explain that manned spacecraft need to take food,
water and oxygen.
Manned space travel
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 (probes) do not need food,
water or oxygen.
Unmanned space travel
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
43
Near Earth Objects
A Near Earth Object (NEO) is an asteroid or comet
on a possible collision course with the Earth.
44
Evidence about the origins of the universe
45
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.
46
Evidence 2 - Redshift
47
If you pass the light through a gas something
different is seen
Some wavelengths of light are absorbed by the gas
an absorption spectrum.
48
If the light source is moving away the absorption
spectra look a little different
helium
49
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
50
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.
51
Red shift summary
wavelength
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.
away
further
faster
billion
big bang
Words to use faster, away, big bang, billion,
wavelength, further
52
The Life and Death of a Star
53
Nebulae
A nebulae is a collection of dust, gas and
rock. Some examples of nebulae
54
Dark nebula
55
Emission nebula
56
Planetary nebula
57
Reflection nebula
58
Protostar
59
Main Sequence
balanced
temperatures
nuclear
hydrogen
heavier
60
Red Giants
Eventually the fuels will run out. When this
happens the star will become colder and redder
and start to swell
61
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
62
2) Heavy weight stars will shrink and then
EXPLODE, releasing massive amounts of energy,
dust and gas.
This explosion is called a SUPERNOVA
63
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.
64
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.
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