Transcript electric charge - National Physical Laboratory

Protons for Breakfast
Electricity
Week 1
February 2013
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.
Andrew Hanson
Who
is helping?
Andy Knott
Averil Horton
Bufa Zhang
Cat Fitzpatrick
Chantal Mustoe
Claire Greenwell
David Clay
Deborah Lea
Edward Brightman
Emma Woolliams
Gianluca Memoli
Jacquie Elkin
James Claverley
James Miall
Jane Burston
Jane Scott
Jeff Flowers
Jenny Hully
Jenny Wilkinson
John Gallop
John Makepeace
John Mountford
Jonathan Pearce
Jordan Tompkins
Joseph Thom
Kate Wilkinson
Laurie Winkless
Lindsay Chapman
Lloyd England
Louise Brown
Maria Lodeiro
Marta Doval Minarro
Paul Carroll
Paul Green
Peter Benson
Peter Edmead
Peter Nisbet-Jones
Peter Quested
Peter Woolliams
Rainer Winkler
Ralf Mouthaan
Robert Goddard
Ruth Montgomery
Ruth Pearce
Sharmila Hanson
Stephanie Bell
Sue Gibbons
Thanks
•
NPL:
The National Physical Laboratory
•
Serco:
Manage NPL on behalf of the BIS
•
Amey:
Who set out the rooms
Member
the Podesta
Most Excellent Order of the British Empire!
Michaelof de
Age 52:
• Lecturer in Physics at
University of London for 13
years
• Understanding the Properties
of Matter
• At NPL for 12 years.
• Most accurate thermometer
ever made!
• International Surface
Temperature Initiative
• Married with two sons
(aged 14 & 16)
• Keen on Water Rockets
Why am I here?
I am here because I believe …
Science is humanity’s greatest achievement
Why are you here?
•
•
•
•
•
•
•
I love anything science.
I have an interest in science and want my children to come on
the course
I always wanted to attend, since my husband brought me there
one night as a birthday treat (!)...and I am a great fan of the
blog.
Want to be a scientist
I want to learn more about the greenhouse effect.
To show that there is art in science and good science requires
imagination.
To inspire my 13 year old daughter, who is being home educated,
in physics. I also have a significant interest in physics myself.
…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
• Electricity
• How Electricity works
• Atoms
• Light
Tonight’s talk
The scale and size of the Universe
or
‘How not to be boggled!’
The imperceptible and the vast
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
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
Measuring instruments extend our senses
Telescopes & Microscopes,
Weighing machines,
Devices sensitive to electricity & light,
Clocks
NPL: Enables people to trust measurements
Quantities and qualities that
extend beyond our ability to
perceive them seem:
imperceptible or vast
?
?
Science helps us extend our senses
But we can still feel 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
Diameter of
a hair
Diameter of
the Earth
Distance to
the Sun
Powers of Ten
Length
Scale
in
metres
Microbes
Viruses
Quarks
10-18 10-12
Human
Relationships
10-6
Very
Very
Small 10-15 10-9
100
10-3 103
106
Current estimate
of the size of the
universe
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
Diameter of
a hair
Distance to
the Sun
Diameter of
the Earth
Powers of Ten
Length
Scale
in
metres
Microbes
Viruses
Quarks
10-18 10-12
Human
Relationships
10-6
10-15 10-9
100
10-3 103
106
Current estimate
of the size of the
universe
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
Microbes
10-18 10-12
Human
Relationships
10-6
Very
Very
Small 10-15 10-9
100
106
10-3 103
Distance to
the Sun
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
NuclearMicrobes
Power
10-18 10-12
Human
Relationships
10-6
Very
Very
Small 10-15 10-9
100
106
10-3 103
Distance to
the Sun
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
Earth
moves once
around the Sun
Powers of Ten (time)
Time for a
Time scale
in seconds
molecule
to
Light wave
wiggles once
Estimated time
since the big bang
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
1012 1018 1024
109
1015 1021
Lifetime of a
Civilisation
End of last
ice age
Very
Very
Long
Age of the Earth
The Universe
Its very big, but full of very small things
?
?
Tonight’s talk
• The scale and size of the Universe
Its very big, but full of very small things
• Electricity
• How it works
• Atoms
• Light
Electricity
Electricity
How it all fits together…
Electricity
Atoms
Electromagnetic
waves
Heat
EeeeeElectricity
- 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 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
Tonight’s talk
• The scale and size of the Universe
Its very big, but full of very small things
• Electricity
It’s everywhere!
• How it works
• Atoms
• Light
How do we describe
the world?
Stuff
• matter
Not Stuff
• the gaps in
between matter
• fields
How do we describe the world?
How do we describe the world?
Two different kinds of physical entity
Stuff (Particles)
•
•
Atoms
• Electrons
• Neutrons
• Protons
Very small
Not Stuff (Fields)
•
Fields
Gravitational
Electroweak
Strong
•
Extend throughout space
We need to know about both particles and fields
How do charged particles interact?
It’s a three-step process…
Particle
Particle
with electric
charge
Interact by means
of an electric field
…but the steps happen very quickly
with electric
charge
How do we describe the world?
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.
Tonight’s talk
• The scale and size of the Universe
Its very big, but full of very small things
• Electricity
It’s everywhere!
• How it works
There are ‘particles’ and ‘fields’
• Atoms
• Light
How it all fits together…
Electricity
Atoms
Electromagnetic
waves
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
Tonight’s Drama: The importance of being electrical
How are atoms made?
Electrical Repulsion
proton
Interact by the short range
‘strong’ force – not electrical
How are atoms made?
Atomic Structure
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
Atomic Structure
• 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 2O
O
2
H
Atoms &… Ions
• A ion is an atom or molecule which has lost or gained an electron.
H
O
H
The electrical nature of matter
Solids
Atoms in solids
• Atoms can be imaged on a surface
Photo Credit: Patrick Josephs 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
• 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
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
Magnetic Forces
Magnetism
Electric
&
Magnetic
• We call forces ‘magnetic’ when both particles are moving with respect
to us.
• They are still electrical in origin.
• This was first explained by Albert Einstein in his Theory of Relativity
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
Tonight’s talk
• The scale and size of the Universe
Its very big, but full of very small things
• Electricity
It’s everywhere!
• How it works
There are ‘particles’ and ‘fields’
• Atoms
They’re everywhere! And they are all electrical!
• Light
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
…but the steps happen very quickly
with electric
charge
The nature of interactions (1)
Analogy with water level and water waves
Tonight’s talk
• The scale and size of the Universe
Its very big, but full of very small things
• Electricity
It’s everywhere!
• How it works
There are ‘particles’ and ‘fields’
• Atoms
They’re everywhere! And they are all electrical!
• Light
An electro-magnetic wave
How it all fits together…
Electricity
Atoms
Electromagnetic
waves
Heat
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
•
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
Links to other sites & resources
Me going on about things
Goodnight
See you next week!
Don’t forget your
pencils and
badges!
Goodnight