Protons for Breakfast
Week 1: Electricity
November 2009
In the event of an alarm sounding…
Toilets…
Parents and children…
The plan for the evening…
More talk
Talk
7:00 p.m.
to
7:59 p.m.
Walkabout
8:00 p.m.
to
8:29 p.m.
8:30 p.m.
to
8:59 p.m.
Feedback
8:59 p.m.
to
9:00 p.m.
Who is helping?
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•
Amanda Law
Andrew Hanson
Arzu Arinc
Averil Horton
Bufa Zhang
Deborah Lea
Emma Woolliams
Gianluca Memoli
Heather Browning
Jacquie Elkin
James Miall
Jeff Flowers
Jenny Wilkinson
Jian Wang
Joanna Lee
John Makepeace
John Mountford
•
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Jonathan Pearce
Laurie Winkless
Lindsay Chapman
Mateusz Szymanski
Matthew Tedaldi
Clive Scoggins
Neelaksh Sadhoo
Paul Carroll
Peter Quested
Peter Woolliams
Piers de Lavison
Rainer Winkler
Richard Gilham
Robin Underwood
Ruth Montgomery
Sharmila Hanson
Stephanie Bell
Tim Burnitt
Acknowledgements
• NPL:
– The National Physical Laboratory
• Serco:
– Manage NPL on behalf of the BIS
• Amey:
– Who set out the rooms
• Baxter Storey:
– Who do the tea & biscuits
Who is Michael de Podesta?
Age 49:
• Lecturer in Physics at
Birkbeck College and
University College
London for 13 years
• Scientist at NPL for 9
years.
• Building the most
accurate thermometer
ever.
• Married with two sons
(aged 11 & 13)
• Keen on Water Rockets
• MBE!
MBE!
Why are you here?
A selection of your reasons for attending…
•
•
•
•
•
•
•
•
My son and I are very interested in learning about science
To improve my understanding and my teaching of Physics.
I am interested in all aspects of science and how it affects us
and everything around us.
To try to understand more about the world (more than I can
take in from reading)..
I love Physics! I am very interested in Physics as a potential
career.
It looks very interesting and I want to share the experience
with my daughter who will then be in Year 8.
Poor Science lessons at my grammar school. Teachers seemed
more concerned with neat writing
Near total ignorance. No Physics since 1944
Why am I here?
I am here because I believe …
Science is humanity’s greatest achievement
But there is a problem about how we,
as citizens, relate to science…
The image of science:1
Mad Muppets top cult science poll
Dr Honeydew is known the
world over for his
disastrous research at
Muppet Labs,
"where the future is being
made today".
His experiments invariably go awry, with poor old Beaker
usually being blown to bits or electrocuted.
BBC 6/9/2004
The image of science:2
Science Gone Wrong
The final touch…
What!
BANG!
Alex Noble (Age 9)
The image of science:3
An un-scientific experiment
Scientist
……… Scientist
In contrast…
• A room full of people who want to learn about science
• Helped by volunteers
• In a world where ignorance makes us powerless
Tonight’s talk
• The scale and size of the Universe
– Its very big, but full of very small things
• The electric force
– It dominates every physical phenomenon on our scale.
• How the force works
– Electric particles
– Electric field
• Light
– Waves in the Electric field
Tonight’s talk
The scale and size of the Universe
Or
‘How not to be boggled’
The imperceptible and the vast (1)
As human beings we can judge:
• temperatures close to ‘normal’
• weights greater than a gram up to around 1000 kilograms
• distances greater than a millimetre or less than a few kilometres.
• times greater than a second or less than a fraction of a lifetime.
The imperceptible and the vast (2)
As human beings we cannot judge:
• temperatures more a few degrees away from ‘normal’
• Such temperatures just feel ‘very hot’ or ‘very cold’
• weights beyond a few tonnes or less than a gram
• Such weights seem either stupendously heavy or negligible
• distances less than a millimetre or greater than a few kilometres.
• Such distances are too tiny or too far to perceive directly
• times less than a second or more than a fraction of a lifetime.
• Such times are too small or too long for us to appreciate
The imperceptible and the vast (3)
Quantities and qualities that
extend beyond our ability to
perceive them often seem:
imperceptible or vast
?
?
The imperceptible and the vast (4)
• Measurement: Quantitative comparison
• Measuring instruments extend our senses
•
•
•
•
Telescopes & Microscopes,
Weighing machines,
Devices sensitive to electricity & light,
Clocks
• NPL
• Enables people to trust measurements
The imperceptible and the vast (5)
• We can be unaware of things because they are
–
–
–
–
Too small
Too large
Change too quickly
Change too slowly
• Science can help us to quantitatively assess matters we
commonly perceive as imperceptible or vast
– But these things can still induce a feeling of being ‘boggled’
The Planet Earth
Diameter:
12,800 km
Deepest hole:
10 km
Atmosphere:
10 km
Photo Credit: NASA
The Moon
Diameter
Earth:
12,800 km
Moon:
3476 km
Photo Credit: NASA
The Sun
Diameter:
1,390,800 km
Photo Credit: NASA
Powers of Ten
I hope that you are now a little unsettled and ready to go on a
9 minute journey to see how the world looks at different
levels of ‘fantasy magnification’
Photo Credit: Powers of 10
Powers of Ten (1)
1 metre
1000000000000 m
0.000001 m
Very
Very
Small
1000000 m
1000 m
0.001 m 1000000000 m
Very
Very
Large
0.000000001 m
Can you see the problem with very small and very large numbers?
Powers of Ten (2)
10
10
10-18 10-120.000001
10-6
1000000
106 1012 1018 1024 1030 1036
Very
Very
Small 10-15 10-9 0.001
10-3 1000
103
109
1015 1021 1027 1033
Very
Very
Large
Powers of Ten (3)
1 metre
1000000000000 m
0.000000000001 m
10-18 10-12
10-6
Very
Very
Small 10-15 10-9
10-3 103
106
1012 1018 1024 1030 1036
109
1015 1021 1027 1033
Very
Very
Large
of
Powers of Ten Diameter
a hair
Length Scale in metres
Viruses
Diameter of
the Earth
Distance to
the Sun
Current estimate
of the size of the
universe
Microbes
Quarks
10-18 10-12
Human
Relationships
10-6
Very
Very
Small 10-15 10-9
100
10-3 103
106
1012 1018 1024 1030 1036
109
1015 1021 1027 1033
Nuclei
of atoms Atoms &
molecules
Nanotechnology Tallest Mountain
Light Year
?
Very
Very
Large
Nearest Star
of
Powers of Ten Diameter
a hair
Length Scale in metres
Viruses
Distance to
the Sun
Diameter of
the Earth
Current estimate
of the size of the
universe
Microbes
Quarks
10-18 10-12
Human
Relationships
10-6
10-15 10-9
100
10-3 103
106
1012 1018 1024 1030 1036
109
1015 1021 1027 1033
Nuclei
of atoms Atoms &
molecules
Nanotechnology Tallest Mountain
Light Year
Nearest Star
Diameter of
the Earth
Powers of Ten
Global Warming
Distance to
the Sun
Microbes
10-18 10-12
Human
Relationships
10-6
Very
Very
Small 10-15 10-9
100
106
10-3 103
1012 1018 1024 1030 1036
109
1015 1021 1027 1033
Atoms &
molecules
Tallest Mountain
Very
Very
Large
The phenomenon of
global warming involves
physical processes with
length scales spanning 20
powers of 10!
Diameter of
the Earth
Powers of Ten
Nuclear Power
Distance to
the Sun
Microbes
10-18 10-12
Human
Relationships
10-6
Very
Very
Small 10-15 10-9
100
106
10-3 103
1012 1018 1024 1030 1036
109
1015 1021 1027 1033
Nuclei
of atoms Atoms &
molecules
Tallest Mountain
Very
Very
Large
The issues surrounding
nuclear power involve
physical processes with
length scales spanning 25
powers of 10!
1 second
Powers
Light waveof Ten (time)
wiggles
once inTime
for a
Time scale
seconds
Earth
moves once
around the Sun
molecule to
jiggle once
10-18 10-12
10-6
Very
Very
short 10-15 10-9
Sound
travels 1
metre
100
106
10-3 103
Fastest
response
of human
eye
A human
lifetime
Estimated time
since the big bang
1012 1018 1024
109
1015 1021
Lifetime of a
Civilisation
End of last
ice age
Very
Very
Long
Age of the Earth
The imperceptible and the vast
The Universe
– Its very big, but full of very small things
?
?
Electricity
Electricity
Now we can begin…
Electricity
Electromagnetic
waves
Atoms
Heat
Electricity
Eeeee - lec- tric-ity
Electricity
Some experiments…
Lets take a look at some odd
phenomena…
• A balloon and a piece of paper
Lets take a look at some odd
phenomena…
• If I balance my glasses carefully…
Even a sausage…
• Sausages…
…its everything…
The balloon affects anything and everything nearby
To understand this, we need to understand
• what matter is made of, and
• how this ‘influence’ is communicated across ‘space’
A simple scientific instrument:
The gold leaf electroscope
• Scientists can develop
instruments to
measure the relative
strengths of the
‘electric influence’
• Based on the same
effect we saw with bits
of paper
The Van de Graaff Generator
• Scientists can develop machines to automate and amplify
the ‘rubbing’ process with the balloon
Photo Credits: Katherine Robinson and MIT
The Van de Graaff Generator
It is not important to understand how a Van de Graaff generator works
PictureCredits: http://www.ikp.uni-koeln.de/~3T/tandem-prinzip1.htmlhttp://science.howstuffworks.com/vdg1.htm
The Van de Graaff Generator
It is not
important to
understand how
a Van de Graaff
generator works
The Wimshurst Machine
Sorry: I cannot easily explain how a Wimshurst Machine works!
Photo Credits: Wikipedia and http://www.coe.ufrj.br/~acmq/electrostatic.html
Electrostatic Generators
• People have been doing this for a long time…
Photo Credits: http://www.ikp.uni-koeln.de/~3T/tandem-prinzip1.html
Conclusion…
Electricity is present inside ALL matter
Its ‘influence’ can be communicated
across ‘empty’ space
How do we describe
the world?
Stuff
• matter
Not Stuff
• the gaps in
between matter
• fields
How do we describe the world?
Two different kinds of physical entity
Stuff (Particles)
Not Stuff (Fields)
•
•
•
Atoms
• Electrons
• Neutrons
• Protons
Very small
•
Fields
• Gravitational
• Electroweak
• Strong
Extend throughout space
We need to know about both particles and fields
The electrical nature of matter
Particle
Particle
with electric
charge
Interact by means
of an electric field
with electric
charge
Tonight’s talk…(3)
• The scale and size of the Universe
– Its very big, but full of very small things
• The electric force
– It affects everything
• How the force works
– Electric particles
– Electric field
• Light
– Waves in the Electric field
The electrical nature of matter
•
Electric charge is a fundamental property of electrons and protons.
•
Two types of charge (+ and -)
• If particles have the same sign of electric charge they repel
• If particles have different signs of electric charge they attract
• The forces (attractive or repulsive) get weaker as the particles get
further apart.
The electrical nature of matter
•
Electric charge is a fundamental property of electrons and protons.
•
Two types of charge (+ and -)
• If particles have the same sign of electric charge they repel
• If particles have different signs of electric charge they attract
• The forces (attractive or repulsive) get weaker as the particles get
further apart.
How it all fits together…
Electricity
Electromagnetic
waves
Atoms
Heat
Atoms
Atoms
Protons, neutrons and electrons
normally exist inside atoms
Atoms
Atoms are small
• Think of a millimetre
1 mm
• Atoms are roughly
10,000 times smaller
than this…
0.1 mm
0.01 mm
0.001
mm
Atoms
• There are VAST numbers of atoms in
everything.
– In just a handful of anything there are about
the same number of atoms as there are grains
of sand on all the beaches and deserts on
Earth combined
Photo Credit: http://www.morguefile.com ID = 104101
The electrical nature of matter
Atoms
Internal Structure
How are atoms made?
Electrical Repulsion
proton
Interact by the short range
‘strong’ force – not electrical
How are atoms made?
Atoms (4)
Electrons
• ‘orbit’ around the outside of an atom
• very light
• possess a property called electric charge
Nucleus
• occupies the centre
• very tiny and very heavy
• protons have a property called electric charge
• neutrons have no electric charge
How are atoms made?
• Nuclei (+) attract electrons (-) until the atom as a whole is neutral
• The electrons repel each other
– They try to get as far away from each other as they can, a
– and as near to the nucleus as they can
The electrical nature of matter
Chemistry
Atoms, Elements & Molecules
Atoms
The Periodic Table
• Atoms with up to about 82 protons can be stable.
• A material made up of a single type of atom is called an element
Atoms
& Molecules
• A molecule is a collection of atoms stuck together electrically.
H
NN
H2
H
N
H
H 20
0
2
H
The electrical nature of matter
Solids
Atoms (3)
• Atoms can be imaged on a surface
Photo Credit: Patrick Joseph Franks: NPL
The electrical nature of matter
•
In ‘normal’ matter, there are equal quantities of positive and negative
charge so that there is no attraction or repulsion of objects.
Object 1
Object 2
The electrical nature of matter
Mechanical Properties
Atoms and mechanics(9)
• Whenever two materials touch, the forces between them are
the forces between the outer (valence) electrons
• All mechanical forces are actually electrical in nature
Object 1
Object 2
The electrical nature of matter
Conductors and Insulators
Atoms in solids (8)
Solids are made up out of lots atoms very close together.
– If the electrons can’t move easily from atom to atom:
• The material is called an insulator
– If the electrons can move easily from atom to atom:
• The material is called a conductor
The electrical nature of matter
How the balloon affected the paper…
Odd phenomena…
• A balloon and a piece of paper
Odd phenomena…
• A balloon and a piece of
paper
The electrical nature of matter
How is the electrical force
transmitted from one charged
particle to another?
How do charged particles interact?
It’s a three-step process…
Particle
Particle
with electric
charge
Interact by means
of an electric field
with electric
charge
…but the steps happen very quickly
The nature of interactions (1)
Analogy with water level and water waves
Tonight’s talk…(4)
• The scale and size of the Universe
– Its very big, but full of very small things
• The electric force
– It affects everything.
• How the force works
– Electric particles
– Electric field
• Light
– Waves in the Electric field
Summary
•
Physics concepts span vast ranges of mass, length and time.
•
The universe has two kinds of objects in it: Matter and Fields
•
All matter (on Earth) is made of atoms which interact electrically.
•
In matter as we normally experience it, there are equal amounts of
the two types of electric charge and their effects cancel
•
If we add or remove some particles with electric charge from
matter then we can see the electrical effects.
Homework?
Homework
• Activity: Remember when you have your breakfast
that you are eating protons and neutrons coated
with tasty electrons.
• Research: What is the ‘frequency’ of your favourite
radio station? Don’t just get the number (98.9, 198
etc.) get the units as well! They should be in
– Hertz
– Kilohertz
– Megahertz
One minute feedback
• On the back of your handouts!
• Rip off the last sheet
• Please write down what is in on your mind RIGHT NOW!
– A question? OK
– A comment? OK
– A surprising thought in your mind? I’d love to hear it!
On-line Resources
• www.protonsforbreakfast.org
–This PowerPoint ™ presentation.
–Handouts as a pdf file
• blog.protonsforbreakfast.org
–Me going on about things
• links.protonsforbreakfast.org
–Links to other sites & resources
Goodnight
See you next week!
Don’t forget your
pencils and
badges!
Goodnight