Living for the Future

1
Living for the Future
(OCR Gateway Additional Science)
W Richards The Weald School
2
P2a Collecting Energy from the Sun
3
Solar Panels and Thermal Towers
What are the advantages and disadvantages of
solar power?
4
Using Solar Energy in remote places
5
Solar Energy
Solar panels convert sunlight directly into
______. Sunlight knocks ______ loose from the
crystal structure and the loose electrons form a
DC electric ______. The amount of power depends
on the ___ of the panel and the light ______ and
the distance to the ____.
Words current, electricity, electrons, sun,
area, intensity
6
Other ways to use solar energy
What are the advantages and disadvantages of wind
power?
7
Passive solar heating
Passive solar heating is the idea of using
solar power to heat homes. Heres how they work

1. Glass is transparent to the suns radiation
2. The thermal mass next to the glass absorbs the
   suns heat energy
3. The surface then emits radiation of longer
   wavelength
4. The glass helps reflect the infra red back inside
   the house

8
P2b Generating Electricity
9
DC and AC
02/01/2015
02/01/2015
V
DC stands for Direct Current the current only
flows in one direction. Batteries supply DC.
Time
1/50th s
AC stands for Alternating Current the current
changes direction 50 times every second
(frequency 50Hz). Household electricity is AC
230V
T
V
10
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

11
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
12
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 the electricity is sent into the National Grid
13
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 (?)
14
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?

15
Efficiency of Power Stations
Heat
Heat
Heat
15J
Boiler
Turbine
Generator
100J
50J
5J
85J
35J
30J
Heat
Kinetic
Electrical
What is the efficiency at each stage of this
power station?
16
P2c Global Warming
The following two graphs are taken from
Wikipedia. What do they imply?
17
02/01/2015
18
02/01/2015
19
The Greenhouse Effect
We get heat from the sun

• Heres how the greenhouse effect works
• Our atmosphere absorbs a lot of infra red
  ________ from the sun
• Short wavelength EM radiation from the sun is
  absorbed by the _______ and heats it up
• The Earth re-radiates heat as _______ wavelength
  EM radiation (i.e. _______ _____)
• Greenhouse gases such as _____, carbon dioxide
  and water vapour absorb some of this infra red
  and re-radiate it back to the Earth causing it to
  ______ up.

Words longer, radiation, Earth, warm, infra
red, atmosphere
20
The Changing Greenhouse Effect
The Greenhouse Effect has been around for
millions of years but scientists are concerned
that it has been increasing in recent decades.
How have the following things affected this?
21
Differing views on Global Warming
The following data shows global warming figures
and projections from different research centres.
What do you notice?
22
P2d Fuels for Power
23
Fuels
A fuel is something that can be burned to
release heat and light energy. The main examples
are
24
Nuclear power stations
These work in a similar way to normal power
stations
25
Biomass
02/01/2015
Biomass is a term used to describe anything
that can be grown or biologically made and then
burned as a fuel
26
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
27
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)
28
Energy and Power
The POWER RATING of an appliance is simply how
much energy it uses every second. In other
words, 1 Watt 1 Joule per second
E Energy (in joules) P Power (in watts) T
Time (in seconds)
29
Some example questions

1. What is the power rating of a light bulb that
   transfers 120 joules of energy in 2 seconds?
2. What is the power of an electric fire that
   transfers 10,000J of energy in 5 seconds?
3. Rob runs up the stairs in 5 seconds. If he
   transfers 1,000,000J of energy in this time what
   is his power rating?
4. How much energy does a 150W light bulb transfer
   in a) one second, b) one minute?
5. Jonnys brain needs energy supplied to it at a
   rate of 40W. How much energy does it need during
   a 50 minute physics lesson?
6. Lloyds brain, being more intelligent, only needs
   energy at a rate of about 20W. How much energy
   would his brain use in a normal day?

60W
2KW
0.2MW
150J, 9KJ
120KJ
630MJ
30
The Cost of Electricity
02/01/2015
Electricity is measured in units called kilowatt
hours (kWh). For example
31
The Cost of Electricity
02/01/2015
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 12p 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

72p
12p
12p
6p
Electricity is cheaper at night time (around 5p
per unit) how much would these devices cost at
night time?
32
Power
02/01/2015
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

• We can use this equation to analyse power
  stations
• A transformer gives out 10A at a voltage of 50V.
  What is its power output?
• An electric fire has a power rating of 2KW. If
  it runs on a voltage of 230V what is the current?
  
• Electricity is transmitted along some lines in
  the National Grid at 400KV. If the current is
  1KA what would be the power through the wire?

500W
8.7A
400MW
33
The National Grid
02/01/2015
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
34
P2e Nuclear Radiations
35
The structure of the atom
36
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 radioactive decay.
37
Background Radiation
38
Blocking Radiation
Each type of radiation can be blocked by
different materials
Sheet of paper
Few mm of aluminium
Few cm of lead
39
Ionisation
Radiation is dangerous because it ionises atoms
in other words, it turns them into positive
ions by knocking off electrons or negative ions
by gaining electrons
Alpha radiation is the most ionising (basically,
because its the biggest). Ionisation causes
cells in living tissue to mutate, usually causing
cancer.
40
Uses of Alpha Radiation
Smoke detectors
Alarm
41
Uses of Beta Radiation
42
Uses of Gamma Radiation
Sterilising medical instruments
Gamma rays can be used to kill and sterilise
germs without the need for heating.
43
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
44
Handling Radioactive Materials
Safety measures

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

Plutonium is a waste product from nuclear power
stations and can be used to make nuclear bombs.
It remains radioactive for a long time and can be
a terrorist risk.
45
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
46
P2f Exploring our Solar System
47
The Solar System summarised
What makes up our solar system? Complete the
following mind map with what you now about each
object
The solar system
48
The eight planets of our Solar System
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
As well as the eight planets, the solar system is
also made up of asteroids, dwarf planets, comets
and moons
49
Distances in space
Definition a light year is the distance
covered by light every year
50
Solar systems, galaxies and the Universe
OUR SUN (100 times wider and 4.6 billion years
old), which is small compared to
THE MILKY WAY, which contains at least 200
billion stars and is 100,000 light years across,
which is small compared to
THE UNIVERSE, which contains billions of galaxies
and is 14,000 million years old.
51
How our Earth and the Sun compare to others
02/01/2015
52
02/01/2015
53
02/01/2015
54
02/01/2015
55
02/01/2015
56
Elliptical Orbits
57
The Earth is kept in orbit by 2 things
Gravity
and by the fact that it is moving at a high
velocity
58
Searching for Aliens
02/01/2015
Humans have been searching for me for over 50
years. Here are some of the methods they use
Since 1960 a group of astronomers have
collectively been sending out EM signals hoping
that someone will send one back!
The Voyager 1 probe, still in operation after
over 33 years and still sending signals back to
Earth.
What are the advantages and disadvantages of each
of these methods?
Soil samples from the moon and, in recent years,
from Mars have been sampled.
59
Space Travel
Advantages
Disadvantages
Manned space travel
Unmanned space travel
60
P2g Threats to the Earth
61
The moon
The moon may be the remians of a very old planet.
The Earth-Moon system was formed due to a
collision between them many years ago
When this collision happened the iron cores
merged to form the core of the Earth and the less
dense material ended up being in the moon. There
are two main areas of evidence for this

1. Similarities in the composition of rocks on the
   Earth and moon
2. The Earths iron core is much bigger than the
   moons

62
Asteroids
An asteroid belt lies between Mars and Jupiter.
But what is an asteroid? An asteroid is a rock
left over from the formation of the solar system.
They are between Jupiter and Mars because the
gravitational attraction of Jupiter disrupted the
formation of a planet.
63
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?

64
Effects of Asteroid collisions
The following things are possible consequences of
an asteroid collision
Oh no

1. Extinction
2. Climate change
3. Sunlight blocked by dust
4. Craters
5. Widespread fires

As well as craters, evidence for asteroid
collisions can also be seen by finding unusual
elements in rocks and sudden changes in fossil
numbers in adjacent rocks.
65
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 due to an increased
gravitational attraction.
66
Near Earth Objects
A Near Earth Object (NEO) is an asteroid or comet
on a possible collision course with the Earth.
How can we monitor and deal with Near Earth
Objects?
67
P2h The Big Bang
68
Evidence about the origins of the universe
02/01/2015
69
02/01/2015
70
02/01/2015
If you pass the light through a gas something
different is seen
Some wavelengths of light are absorbed by the gas
an absorption spectrum.
71
02/01/2015
If the light source is moving away the absorption
spectra look a little different
helium
72
02/01/2015
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
A similar effect happens with sound this is
called The Doppler Effect
73
Red Shift simplified
02/01/2015
Basically, if I walk towards you Ill look
slightly more blue. Then, if I walk away from
you, Ill look slightly more red!! Lets try it
74
02/01/2015
75
02/01/2015
76
Doppler Effect explained
02/01/2015
77
02/01/2015
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.
78
Red shift summary
02/01/2015
79
Cosmic Microwave Background Radiation
02/01/2015
Further evidence of the Big Bang theory is Cosmic
Microwave Background Radiation (CMBR) this
radiation comes from the Big Bang and fills the
_________.
Basically, at the start of the universe,
radiation was hot and had high _______. As time
went on the ________and energy of this radiation
dropped which turned it into to ________. This
background microwave _______ is all over the
universe.
Words microwaves, frequency, temperature,
universe, radiation
80
The Life Cycle of a Star
02/01/2015
81
Stage 1 Nebulae
02/01/2015
A nebulae is a collection of dust, gas and
rock. Some examples of nebulae
82
02/01/2015
Dark nebula
83
02/01/2015
Emission nebula
84
02/01/2015
Reflection nebula
85
02/01/2015
Planetary nebula
(This nebula is smaller and will only form a
planet)
86
02/01/2015
Stage 2 Protostar
87
02/01/2015
Stage 3 Main Sequence
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 and this is why the universe now
contains a number of heavier elements.
Our sun is an example of a main sequence star
its in the middle of a 10 billion year life span
Words heavier, balanced, hydrogen, nuclear,
temperatures
88
02/01/2015
Stage 4 Red Giant
Eventually the hydrogen and helium will run out.
When this happens the star will become colder and
redder and start to swell
89
02/01/2015
Stage 5 The Death
What happens at this point depends on the size of
the star 1) For SMALL stars the red giant will
collapse under its own gravity and form a very
dense white dwarf
90
02/01/2015
2) If the star was a RED SUPERGIANT it will
shrink and then EXPLODE, releasing massive
amounts of energy, dust and gas.
This explosion is called a SUPERNOVA
91
02/01/2015
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 is big enough it could become a BLACK
HOLE instead.
92
Black Holes
A black hole is an object that is so small and
dense that its escape velocity is greater than
the speed of light. In other words, not even
light can escape its gravitational pull.
Fascinating
93
02/01/2015
Stage 6 Second generation stars
The dust and gas thrown out by a supernova can be
used to form a new star
94
The Life Cycle of a Star summary
02/01/2015
Protostar
SMALL stars
BIG stars
Main sequence
Red super giant
Red giant
Supernova
White dwarf
Black dwarf
Neutron star
Black hole
Basically, it all depends on the size of the star!
95
Our understanding of the universe
Up until the 16th Century people believed that
the Earth was the centre of the universe this
is called the Geocentric model and I made a
model of the universe based on it.
I published my On the revolutions of the
celestial spheres just before my death and
showed that the Earth and other planets orbit
around the sun the Heliocentric model.
96
Evidence for the Heliocentric Model
I helped develop the modern telescope and made
measurements with it that proved that the
Copernican model of the solar system was correct
but a lot of people didnt like it because the
old Catholic Church didnt like it.