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    MAGNETIC

    LEVITATION

    B Y - A R C H I T E N 3 R D 0 8 0 0 3 2 1 4 0 3

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    WHAT IS A MAGNET?

    It is simply an object which produces amagnetic field

    North and South are the designations madeto describe the two opposite poles

    North is attracted to South and repelled byNorth

    South is attracted to North and repelled bySouth

    There are three main types:

    - Permanent Magnets- Soft Magnets- Electromagnets

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    PERMANENT MAGNETS

    Electrons fill atomic orbitals in pairs

    If an orbital is full, then one electron spinsupward and the other spins downward(Pauli Exclusion Principle), so theirmagnetic fields cancel out

    If an orbital is not full, then the movementof the electron creates a tiny magneticfield

    Atoms with several unpaired orbitals havean orbital magnetic moment

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    PERMANENT MAGNETS

    In metals, the orbital magnetic

    moment causes nearby atoms

    to align in the same direction,creating a ferromagnetic metal

    The strength of the magnetic field

    decreases inversely with the

    cube of the distance from themagnets center

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    SOFT MAGNETS

    These types of magnets do not have a magnetic field of their own

    However, when put in the presence of another objects magnetic field, they are

    attracted (paramagnetic)

    Once the external magnetic field is removed, they return to their nonmagnetic state

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    ELECTROMAGNETS

    The magnetic field is caused by the flowof an electric current

    The simplest example is a coiled piece

    of wire

    Using the right hand rule, it is possibleto determine the direction

    An advantage over permanent magnets

    is that the magnetic field strengthcan be changed by changing thecurrent

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    NINEWAYS TO MAGNETICALLY LEVITATE

    AN OBJECT

    Mechanical constraint

    Direct diamagnetic levitation

    Superconductors

    Diamagnetically-stabilized levitation

    Rotational stabilization

    Servo stabilization

    Rotating conductors beneath

    magnetsHigh-frequency oscillating

    electromagnetic fields

    Translational Halbach arrays andInductrack

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    DirectDiamagnetic Levitation HowitWorks

    Diamagnetic materials repel a magneticfield

    All materials have diamagnetic properties,

    but the effect is very weak, and usuallyovercome by the objects paramagneticor ferromagnetic properties, which actin the opposite manner

    By surrounding a diamagnetic materialwith a magnetic field, it can be held in astationary position (the magnetic forceis strong enough to counteract gravity)

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    DirectDiamagnetic Levitation Applications

    Water is primarily diamagnetic, so water droplets and

    objects that contain large amounts of water can be

    levitated

    http://www.hfml.ru.nl/pics/Movies/frog.mpg

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    SUPERCONDUCTORS

    A superconductor is an element, inter-metallic alloy, or acompound that will conduct electricity without resistancebelow a certain temperature.

    Resistance produces losses in energy flowing through thematerial.

    In a closed loop, an electrical current will flow continuouslyin a superconducting material.

    Superconductors are not in widespread use due to the cold

    temperatures they must be kept atHighest Tc found 150K

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    APPLICATIONS

    MagLev Trains- The magnetized coil running alongthe track, repels the large magnets on the train'sundercarriage, allowing the train to levitate

    Biomagnetism- in MRI and SQUID (measures

    slight magnetic fields)Particle accelerators to accelerate sub-atomicparticles to nearly the speed of light

    Electric generators- made with superconductingwire: They have a 99% efficiency and have abouthalf the size of conventional generators.

    Really fast computers- In "petaflop" computers. Apetaflop is a thousand-trillion floating pointoperations per second. Today's fastest computingoperations have only reached "teraflop" speeds.

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    Applicationssoontocome

    Stabilizing momentum wheel (gyroscope) for earth-orbitingsatellites- can reduce friction to near zero

    Superconducting x-ray detectors and superconducting lightdetectors - able to detect extremely weak amounts ofenergy.

    Superconducting digital router- for high-speed data

    communications up to 160 GhzPower plants use to reduce greenhouse gas emissions

    Advancements depend to a great degree on advancements inthe field of cryogenic cooling or finding more high-temperature superconductors

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    ROTATIONAL MAGNETISM

    Also known as spin stabilized magnetic levitation

    Happens when the forces acting on the levitating object- gravitational, magnetic, and

    gyroscopic- are in equilibrium

    Earnshaws theorem says it is impossible

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    SUPER LEVITRON

    Two opposing neodymium-iron-boron permanent magnets.

    original invention by Roy Harrigan and patented in 1983.

    He didnt known about Earnshaws theorem which many thoughtsaid such an invention was impossible.

    The rotation of a spinning objects axis of spin creates a toriod ofgenuine stability in a way that does not violate Earnshaws

    theorem, but that went completely unpredicted by physicists formore than a century.

    The top remain levitating in a central point in space above the basewhere the forces acting on the top- gravitational, magnetic, andgyroscopic- are in equilibrium

    Stops due to air resistance

    http://www.levitron.com/images/levitron.mpghttp://www.levitron.com/images/levitron-drbob.mpg

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    WHY ITWORKS

    The principle is that two similar poles (e.g.,two north's) repel, and two different polesattract, with forces that are stronger whenthe poles are closer. There are fourmagnetic forces on the top: on its northpole, repulsion from the base's north andattraction from the base's south, and on itssouth pole, attraction from the base's northand repulsion from the base's south.Because of the way the forces depend ondistance, the north-north repulsiondominates, and the top is magneticallyrepelled. It hangs where this upwardrepulsion balances the downward force of

    gravity, that is, at the point of equilibriumwhere the total force is zero.

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    HOW TO GET IT TOWORK

    Correct magnetic strengths

    Mass of the top must be right

    within .5%Magnets are temperaturedependent, weaker in warmertemperatures

    Correct spinning rate (not toofast or slow)

    Must be introduced onto a smallstabile region only millimeters

    wide and high

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    REFERENCES

    http://www.physics.ucla.edu/marty/levitron/spinstab.pdf

    http://www.superconductors.org/uses.htm

    http://www.popsci.com/popsci/how20/be199aa138b84010vgnvcm1000004eecbccdrcrd.html

    http://www.chem.yale.edu/~chem125/levitron/levitron.html

    http://science.howstuffworks.com/magnet3.htm

    http://www.howstuffworks.com/electromagnet.htm

    http://en.wikipedia.org/wiki/Magnet

    http://en.wikipedia.org/wiki/Electromagnet

    http://en.wikipedia.org/wiki/Magnetic_levitation

    http://my.execpc.com/~rhoadley/maglev.htm

    http://www.hfml.science.ru.nl/hfml/froglev.html