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Magnets

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Magnets are materials that produce a magnetic field of their own. ... been magnetized, and (2) 'soft' or 'impermanent' magnets (like the material of a ... – PowerPoint PPT presentation

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Title: Magnets


1
Magnets
  • Jiacheng Xu
  • Tao Chen
  • Chu Wu

2
What we learn in class
  • Recall that a magnet is a material or object that
    produces a magnetic field.
  • Our Professor mentioned a little about magnets.
    Now, we will continue to learn more about Magnets

3
What are Magnets
  • Magnets are materials that produce a magnetic
    field of their own. Extreme examples of magnets
    are (1) "hard" or "permanent" magnets (like
    refrigerator magnets), which remember how they
    have been magnetized, and (2) "soft" or
    "impermanent" magnets (like the material of a
    refrigerator door)

4
Two types of Magnets
  • lodestone
  • natural permanent magnet
  • exert a force on objects without any outside
    influence
  • electromagnets
  • They are made by surrounding certain materials
    with a coil of wire.
  • When an electric current is passed through the
    coil, these materials exert a magnetic force.

5
lodestone VS electromagnets
lodestone
6
How do Magnets work
  • The molecules in magnets are arranged so
    that the electrons spin in the same direction.
    This arrangement of atoms creates two poles in a
    magnet, a North-seeking pole and a South-seeking
    pole.

The magnetic force in a magnet flows from the
North pole to the South pole. This creates a
magnetic field around a magnet.
7
How do Magnets work
  • If you try to push the South poles or north
    poles together, they will repel each other.
  • If you try to push the south pole and north pole
    together, they will attract each other.

8
Temperatures and Magnets
  • The maximum temperature that a magnet may
    be effectively used at depends greatly on the
    'permeance coefficient' - which is a function of
    the magnetic circuit - the magnet is operating
    in. The higher the permeance coefficient (the
    more 'closed' the circuit), the higher
    temperature at which the magnet may operate at,
    without becoming severely demagnetized. Shown
    here are approximate maximum operating
    temperatures for the various classes of magnet
    material. At temperatures close to those listed
    here, special attention may be needed in order to
    ensure that the magnet will not become
    demagnetized.

9
Temperatures and Magnets
10
The use of Magnets
  • Maglev trains
  • Sort magnetic and non-magnetic materials
  • Magnets are also used in compasses

11
Make your own Magnets
  • What you need
  • card stock or any other heavy paper
  • magnetic tape
  • markers or crayons

12
Make your own Magnets (Cont.)
  • What you do
  • Cut a little piece of any shapes from the card
    stock and color it with markers or crayons.
  • Place a small piece of magnetic tape onto the
    back of the magnet. Make sure to remove the
    backing!
  • Use the magnets to stick paper or sheets on your
    fridge or any other metal surface.

13
Reference
  • http//www.coolmagnetman.com/magreview.htm
  • http//www.squiglysplayhouse.com/ArtsAndCrafts/Cra
    fts/Magnets.html
  • http//images.google.com/imgres?imgurlhttp//www.
    launchpnt.com/fileadmin/maglev/CloseUp_01_web.jpg
    imgrefurlhttp//www.launchpnt.com/Maglev_PRT.480.
    0.htmlh169w300sz16hlenstart37tbnidNW62
    MzoSfeLFrMtbnh65tbnw116prev
  • http//images.google.com/imgres?imgurlhttp//www.
    uscg.mil/diversity/COMPASS/Compass_pin.JPGimgrefu
    rlhttp//www.uscg.mil/diversity/COMPASS/h461w
    512sz33hlenstart3tbnidWqjdvRPo-7VuSMtbnh
    118tbnw131prev
  •  http//images.google.com/imgres?imgurlhttp//www
    .materialflow.com/MFG-PRODS/Aigner-Index/Magetic-R
    oll-Stock.jpgimgrefurlhttp//www.materialflow.co
    m/Label-Holders-Magnetic.htmh299w313sz10hl
    enstart36tbnidtCkey6EMWWJTjMtbnh112tbnw11
    7prev
  •  http//images.google.com/images?qMagnetsgbv2n
    dsp18svnum10hlenstart54saN
  • http//en.wikipedia.org/wiki/Magnets
  •  http//www.eia.doe.gov/kids/energyfacts/sources/e
    lectricity.html
  •  http//www.magnetsales.com/index.htm

14
Thank you
Jiacheng Xu Tao Chen Chu Wu
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