Chp' 32 Magnetism of Matter slide 1

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• Chapter 32
• Magnetism of Matter
• AIMS
• Magnets
• Earths Magnetic Field
• Origin of Magnetism
• Magnetic Materials
• Diamagnetism
• Paramagnetism
• Ferromagnetism

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32-3 The Magnetism of Earth
Law of induction 1831 (Faraday -
England) (Henry - USA)
Equator 30 ?T, Poles 60 ?T Earths core few
thousand oC
Modern technology Magnetic tapes disks
(video recorders, credit cards,
computers) Motors, Generators, Telephones,
Transformers
Yamanashi MLX01 Maglev train 552 km.h-1
http//www.csupomona.edu/sci/impact/sapages/elect
ro_magnet.htm http//www.rtri.or.jp/rd/maglev/html
/english/maglev_frame_E.html
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32-4 Magnetism and Electrons

• BACKGROUND INFORMATION
• 29-9 The Magnetic Dipole
• ? Magnetic dipole moment
• Vector which describes a dipoles magnetic
  properties

Atom spinning electron orbital electron
?S ?orb
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32-5 Magnetic Materials Paramagnetic Diamag
netic Ferromagnetic Ferrimagnetic Antiferrom
agnetic
Ferromagnetism ? exchange coupling
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Diamagnetism No external B-field ? No net
dipole moment no. of e- clockwise no. of e-
anti-clockwise External B-field induces a
magnetic moment (?) opposite to external B-field
direction. Superconductors (? ? 0) frictionless
bearings (repelling magnetic force).
Paramagnetism No external B-field ? No net
dipole moment spin and electron orbit moments
are randomly oriented and cancel one another.
B-field induces a magnetic moment (?) parallel
to external B-field direction.
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