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A Level Course Units
Transport on Track
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Railway systems have,
almost from their beginnings, made use of physics-related
technology and this unit examines various principles involved
today. How are short-circuits used in signalling systems
and what problems can be caused by saline ballast or leaves
on the line?
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What techniques can
be used to sense the speed of a train and control it via
an on-board computer? How could eddy-currents provide a
non-contact braking system? These are just a few of the
electrical and electronic elements of this course unit.
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The past four decades
or so have seen improvements in the design of rolling stock
and this is one of the elements that provides opportunities
for students to look at momentum and energy conservation,
and consider carriage and buffer designs that minimise the
forces on passengers in collisions.
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The above picture
was obtained with Pico
Technology's PicoScope and their ADC42 interface
and shows a graph of Voltage (Force) against Time with a
relatively soft buffer. It works fine with their more recent
DrDAQ too.
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The main physics content areas are:
- DC circuits and
switching
- Force,
momentum, work and energy
- Magnetic
fields: electromagnetic force
- Electromagnetic
induction
- Capacitors:
exponential discharge
The Medium is the Message
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Communications within
modern aircraft provides the context for this unit which
tackles the physics involved in modulation, multiplexing,
digital to analogue (D to A) and analogue to digital (A
to D) conversion. It broaches the issues of how one can
sense the positions of ailerons, flaps, nosewheels and the
like, and send that information to a computer along with
lots of other data.
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This leads to
a consideration of optical fibres and coaxial cables, their
advantages and disadvantages, how different types of optical
fibre can reduce the effects of dispersion, and the exponential
nature of attenuation. The
Philip
Harris Fibre Optics Apparatus shown alongside
demonstrates how modulation can aid the transfer of data.
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The production
of images with charge coupled devices (CCDs) is modelled
with solar cells and capacitors, providing opportunities
to study their effects and behaviour.
Finally the cathode
ray tube (CRT), light emitting diode (LED) and liquid crystal
display (LCD) involve students in work on thermionic emission,
the acceleration of electrons, and the behaviour of charged
particles in electric and magnetic fields.
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The main physics content areas are:
- Digital
and analogue signals
- Capacitors:
energy
- Fibre
optics: refraction; exponential attenuation
- Uniform
electric field
- Charged
particles in a magnetic field
Probing the Heart of
the Matter
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Cosmology and particle
physics are two areas of fundamental research that students
often hear of through the media.
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This unit gives some
insight into these, allowing students to (i) see how particles
can be accelerated, (ii) why high energies are needed to
break particles into their constitutents and to see fine
structure and (iii) see and inquire into the results of
collisions and other interactions.
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Through reading,
work on various websites and the use of packages such as
the Lancaster
Particle Physics software
shown above, the students will also study the development
of the nuclear model, the quark-lepton model to describe
the behaviour of matter on a sub-atomic scale, and see how
current knowledge supports the Big Bang theory of how the
Universe came into being.
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The main physics content areas are:
- Alpha scattering:nuclear
model of the atom
- Electrostatic
force between point charges
- Collisions:
momentum and energy
- Motion
in a circle
- Mass-energy
interconversion
- Charged
particles in electric and magnetic fields
- The
quark-lepton model
Reach for the Stars
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How can one deduce
the distance to galaxies? What can stellar spectra tell
us about stars? How do stars form, evolve and die? What
is the energy source of stars? What is the ultimate fate
of the Universe? These questions are broached in this unit
which looks at the Doppler Shift of line spectra, the Hubble
Constant, nuclear fusion and radioactive decay amongst much
more.
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The pictures above and alongside are
from the The Large Scale Structure of the Universe simulation
from the CLEA
software suite of programs. By measuring the shift of spectral
lines students can deduce the speed of recession of a galaxy
and hence its distance from us.
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Gravitation is approached
through studying the expanding universe and stellar orbits,
and a study of stars and their formation leads to the molecular
kinetic theory of matter.
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The main physics content areas
are:
- Inverse-square
law for radiation
- Universal
gravitation; gravitational field
- Energy
conservation:gravitational, kinetic
- Motion
in a circle
- Nuclear
fusion, fission and radioactive decay
- Molecular
kinetic theory
Build or Bust?
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Building design
provides opportunities to look at vibrations, resonances
in structures, and how to damp such vibrations by selective
use of materials. The picture alongside shows a model structure
under test on an 'earthquake' vibrating table.
Here the students deal
specifically with making buildings more resistant to earthquake
damage, and to insulate them from the vibrations caused,
for example, by underground railways situated beneath or
nearby.
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The pictures below
and alongside show an investigation into the speed of sound
in a steel bar by timing the contact between a hammer and
the bar.
The time of contact
is equal to the time it takes for the pulse to travel down
the bar and back.
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This resulting
speed is related to the properties of the steel and the
way in which waves travel through it.
Again
Pico Technology's PicoScope
has been used to capture the timing information, this time
using their DrDAQ interface.
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In addition the unit
looks at how noise can be measured and controlled in buildings,
the latter both by absorption and by active noise control.
Here
is where the mathematics of simple harmonic motion (SHM)
is used to model the behaviour of oscillators, and where
students use physical models to explore the behaviour of
structures.
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The main physics content areas
are:
- Simple
harmonic motion
- Forces
vibrations, resonance and damping
- Waves
in solids; refraction
- Mechanical
properties of solid
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