Magnetism Chapter 2

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MagnetismChapter 2

• Magnets
• Lesson 2-2

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Magnetic Attraction

• There are magnetic fields around the Earth and
  around bar magnets.
• At each point around the magnet, the magnetic
  field has both a strength and a direction.

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• Convection currents inside the earth set up
  magnetic field.

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What Makes a Magnet?

• Induced Magnetism magnetism that occurs only in
  the presence of a magnet field

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What Makes a Magnet?

• Magnetism of a material depends on the kind of
  atom it is made of.
• Items that are attracted to a permanent magnet
  have atoms with tiny magnetic fields, therefore
  they can act like magnets.
• A magnetic field cannot exist without a magnetic
  material (one that is attracted to a permanent
  magnet.)

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Domains

• Groups of atoms with aligned magnetic fields are
  called domains.
• If the domains are not aligned, there is no
  magnetism.

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A nonmagnetic material doesnt have any domain
structure.
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Permanent Magnets

• Some materials can become magnets
• Example Iron
• ALNICO
• (an alloy of ALuminum, NIckel, and CObalt)

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Electromagnet

• Electromagnet (emag) magnet produced by passing
  an electric current through a coil of wire that
  has a core material inside.

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Electromagnets at Work

• Electromagnets are useful because
• Their magnetism can be turned off and on
• They are much more powerful than
• a permanent magnet
• Example telephones, junkyard crane

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How Electromagnets Work

• Current flowing through a wire created a magnetic
  field by realigning the domains of the core
  material.

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• Four Factors that Determine the Strength of a
  Electromagnet
• Number of Coils of wire
• 2. Thickness of the wire
• 3. Size of the power supply
• 4. Material of the Core (What it is made of)

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Bibliography

• Aldridge, Bill, Jack Ballinger, and Albert
  Kaskel. Science Interactions Course 3. 3rd ed.
  New York, New York Glencoe, 1995. 57-64.
• Magnetic Field. University of Tennessee. 2008
  http//www.utm.edu/staff/cerkal/ magnetic.htm