Transcript Journey into Physics - megan

Journey into Physics
Created by Keira Favale
August 2007
Journey into Physics
Career
options
What is
physics?
Areas of
physics
Why study
physics?
Physicists
What is Physics?
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Of all the physical sciences, physics is the most basic and fundamental.
Physics has been described as the ‘why things work’ science as it involves
discovering the rules and relationships which describe the nature of the universe.
This involves everything from atoms to galaxies to the universe and everything inbetween.
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Even with the complexity of the world around us, one of the key ideas of physics is
that there is an underlying simplicity and unity in nature. This unity does
not just apply to Earth but also across the universe and throughout time.
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For most of our present and future technology, physics has, or will, provide the
bases for its development. Mobile phones, televisions, satellites, cameras, contact
lenses, nuclear power, rockets, computers, and car design are all examples of
inventions which involve the use of physics concepts. These examples highlight how
interconnected physics is with modern life.
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Physics provides us with a way to understand how and why things work and
interact the way they do.
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Why Study Physics?
Why Study Physics?
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There are many reasons to study physics. To start it is a very interesting subject,
which covers a wide range of topics including mechanics, electronics, optics,
magnetism, and astronomy. But it is not just the understanding of physics concepts
that can be gained from a physics course. By studying physics you have the
opportunity to develop critical and creative thinking skills; skills in
posing, analysing and solving questions; and the opportunity to work as a team. All
of these are valuable skills which can be used throughout life.
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A course in physics involves both hands on experimental investigations and
theoretical analysis. Through physics we can discover how and why
things
work and gain a better understanding of the world around us.
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The knowledge and skills gained through physics can be easy transferred into other
disciplines and this adaptability can lead to a wide variety of career options.
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What is Physics?
Career Options
Career Options
Here are some of the many
options which are available
through the study of
physics.
Industries
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Careers
Astrophysicist
Biophysicist
Engineer
Geophysicist
Particle Physicist
Physicist
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Biomedical technology
Communications
Computing
Electronics
Finance
Laser/ Holograms
Manufacturing
Medical physics
Meteorology
Motor vehicle technology
Photonics
Power generation
Research
Scientific sales and management
Semiconductors
Teaching
Telecommunications
Why Study Physics?
Areas of Physics
Areas of Physics
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Physical Quantities and Measurement
Forces and Motion
Follow the links to a range
Energy and Momentum
of websites to provide
more information about
Wave Motion
each of these areas.
Optics
Electricity and Electronics
Magnetism and Electromagnetism
Astronomy
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Career Options
Physicists
Physical Quantities and Measurement
Constants
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Physical Constants
Gravity g = 9.8m/s/s
Speed of Light c =
2.998x108
m/s
Scientific notation
tera-
1012
T
giga-
109
G
mega- 106
M
Planck’s constant h = 6.626x10-34Js
kilo-
103
k
Mass of electron me = 9.109x10-31kg
milli-
10-3
m
Mass of a proton mp= 1.673x10-27kg
micro-
10-6
μ
nano-
10-9
n
pico-
10-12 p
10-15
Units
Temperature – Kelvin (K)
Energy – Joule (J)
femto-
Capacitance – Farad (F)
Force – Newton (N)
astronomical unit 10-10
Frequency – Hertz (Hz)
Pressure – Pascal (Pa)
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Areas of Physics
f
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Forces and Motion
Scalar quantities
Newton’s Laws of Motion
Vector quantities
F = ma
Distance (d)
W = mg
Displacement (s)
Velocity (v)
Acceleration (a)
Uniform Acceleration
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v = u + at
v2 = u2 + 2as
s = 1/2(u + v)t
s = ut +
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Explorelearning – motion
and force – gizmos
Skateboard Science
Mechanics with animations
and film clips
Vectors – Motion and
Forces in two dimensions
Newton’s Laws
1/2at2
Image from: http://www.mansfieldct.org/schools/mms/staff/hand/lawsCentripetalForce_files/image008.jpg
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Areas of Physics
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Energy and Momentum
Kinetic energy KE = ½ mv2
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Gravitational potential energy GPE = mgh
Power P = W/t
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Work, Energy and
Power tutorial
Momentum and
Energy
Work W = Fs cos θ
Machines – levers and pulley
Efficiency
Friction
Conservation of Momentum
Conservation of Energy
Image from: http://sol.sci.uop.edu/~jfalward/physics17/chapter3/chapter3.html
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Areas of Physics
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Wave Motion
Electromagnetic spectrum – visible light 400-700nm
Wavelength (λ)
Period – time of one cycle (T = 1/f = 2π/ω)
Frequency – number of cycles per unit time (f)
Angular frequency ω = 2πf
Wave speed v = λf
Simple harmonic motion – depends only on the mass
(m) and force constant (k)
Standing waves – a wave that stays in the same
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position
Traveling waves – a wave that moves along the
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medium
Longitudinal and transverse
wave motion (Dan Russell,
2006)
Explorelearning -Waves gizmos
Image from: http://uk.encarta.msn.com/media_461517875_761564098_-1_1/Types_of_Wave_Motion.html
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Areas of Physics
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Optics
Object distance (u)
Image distance (v)
Focal length (f)
Snell’s Law 1/v + 1/u + 1/f
Magnification M = |v/u| = Hi (height of
image)/Ho (height of object)
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Ray diagrams
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Angle of incidence (i)
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Angle of refraction (r)
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Refractive index (n)
Science, Optics and You
Thin lens java applet written by
Fu-Kwun Hwang
Image formed by a converging
lens
The Electromagnetic spectrum
Explorelearning – Optics gizmos
Image from: http://www.exploratorium.edu/imagery/stills/Refractive_mixing.jpg
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Areas of Physics
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Electricity and Electronics
Static Electricity – like charges repel, unlike charges
attract
Electric Fields
Series and Parallel Circuits
Ohm’s Law V = IR
Kirchoff’s Laws
P = VI; W=VIt
Resistance (R) – combinations in series and parallel
Conductors – charge can easily move through material
Insulators – charge can not easily move through
material
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P-type and N-type semiconductors
Explorelearning –
Electronics -gizmos
Image from: http://www.dorsetforyou.com/media/images/e/t/CompletedPrintedCircuitBoard.jpg
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Areas of Physics
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Magnetism and Electromagnetism
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Explorelearning –
Magnetism - gizmos
Magnetic Poles – north-seeking and southseeking
Magnetic fields – permanent magnets, current
carrying wires, loops, solenoid
Magnetic Flux – the number of magnetic field lines
passing through a surface
B = kI/r; B = 2πkNI
Units – tesla (one newton per ampere per meter),
EMF is proportional to the rate of
change of magnetic flux (Φ)
EMF = BLv; EMF = -NΔΦ/Δt
Generators and Transformers
Image from: http://en.wikipedia.org/wiki/Magnetism
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Areas of Physics
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Astronomy
The expanding universe
Background radiation
Black holes
Stars, Planets and Galaxies
Kepler’s Laws
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Each planet moves in an elliptical orbit, with the sun at one
focus of the ellipse
2.
A line from the sun to a given planet sweeps out equal areas in
equal time
3.
The periods of the planets are proportional to the 3/2 powers
of the major axis lenghts of their orbits
Introduction to the sky
Main Sequence Stars
Image from: http://solar.physics.montana.edu/gallery/intro.html
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Areas of Physics
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Physicists
Physicists
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Marie Curie
Albert Einstein
Michael Faraday
Stephen Hawking
James Maxwell
Isaac Newton
Home
Follow the links to a range
of websites which cover
the life and achievements
of each of these physicists.
Areas of Physics
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Marie Curie (7/11/1867 – 4/07/1934)
Nobel Prize in Physics 1903 – awarded to Marie
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and Pierre Curie for the discovery of radium and polonium;
award was shared with Antoine Henri Bacquerel
(discovered natural radioactivity)
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Nobel Prize in Chemistry 1911 – awarded to
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Marie Sklodowska Curie
Biography
Marie and Pierre Curie
and the Discovery of
Polonium and Radium
Marie Curie for isolating radium and studying its chemical
properties
Throughout the First World War, Marie Curie
was engaged intensively in equipping more
than 20 vans that acted as mobile field
hospitals and about 200 fixed installations
with X-ray apparatus
Image from: http://hep.ucsb.edu/people/hnn/mcurie.jpg
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Physicists
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Albert Einstein (14/03/1879 – 18/04/1955)
Nobel Prize in Physics 1921 – for his services in
Theoretical Physics, and his discovery of the law of the
photoelectric effect
The Photoelectric Effect – Einstein postulated
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Biography
Einstein – Image and Impact
that a beam of light consists of small packages of
energy called photons or quanta – E = hf = hc/λ
Special Theory of Relativity
First Postulate – Principle of relativity: The laws of physics are
the same in every inertial frame of reference
Second Postulate – The speed of light in a vacuum is the same
in all inertial frames of reference and is independent of the
motion of the source
Implications: (1) Events that are simultaneous for one observer
may not be simultaneous for another (2) When two observers
moving relative to each other measure a time interval or a
length, they may not get the same results
Image from: http://hep.ucsb.edu/people/hnn/Albert_Einstein.jpg
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Physicists
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Michael Faraday (22/09/1791 – 25/08/1867)
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Michael Faraday
Faraday
First introduced the concept of field lines (electric field
lines)
Faraday’s icepail experiment – based on the same principle
is used in a Van de Graaff electrostatic generator and forms the basis for
electrostatic shielding
Faraday and Henry discovered that moving a
magnet near a conducting loop can cause a
current in the loop
Faraday’s Law of induction:
the induced EMF in a closed
loop equals the negative of the time rate of change of magnetic flux through
the loop
Image from: http://www.abdn.ac.uk/~u02rjr4/px2013/Faraday.htm
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Physicists
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Stephen Hawking (8/01/1942)
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Official Website
With Roger Penrose, Hawking showed that
Einstein's General Theory of Relativity implied
space and time would have a beginning in the Big
Bang and an end in black holes.
Hawking discovered that black holes should not be
completely black, but should emit radiation and
eventually evaporate and disappear.
Another conjecture he has made is that the
universe has no edge or boundary in imaginary
time.
Image from: http://hep.ucsb.edu/people/hnn/hawking.jpg
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Physicists
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James Maxwell (13/06/1831 – 5/11/1879)
The first person to truly understand the
fundamental nature of light
Discovered the basic principles of
electromagnetism – Maxwell’s Equations
Displacement current iD – electromagnetic theory
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Maxwell Year 2006
James Clerk Maxwell: a force for physics
Image from: http://hep.ucsb.edu/people/hnn/maxwell.jpg
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Physicists
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Isaac Newton (25/12/1642 – 20/03/1727)
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Newton, Isaac
Sir Isaac Newton
Newton’s Laws of Motion – foundation of classical
mechanics (or Newtonian mechanics)
First Law – An object that is at rest will remain at rest or an object that
is moving will continue to move in a straight line with constant speed, if and
only if the net force acting on that object is zero.
Second Law – The force of an object is equal to the mass of an
object multiplied by its acceleration (F=ma)
Third Law – All forces come in pairs and these two forces are equal in
magnitude and opposite in direction (equal and opposite)
Newton’s Law of Gravitation F = G mAmB
d2
Image from: http://hep.ucsb.edu/people/hnn/newton_1.jpg
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Physicists
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Only just the beginning…
This is only a brief
introduction to the
amazing journey
through Physics. For
more information about
Physics courses
contact your science
teacher, guidance
officer, or choice of
university.
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