Download The Nature of Magnetism

Magnetism &
Electromagnetism
The Nature of Magnetism
Chapter 1
Section 1
Magnets
• Magnetism
– The attraction of a
magnet to another
object
Magnesia (in Greece)
• Used over 2,000
years ago
• Magnetite
– Mineral found in some
rocks
– Fe3O4
• Attracts iron
Lodestones
• Magnets swinging on
strings will eventually
point toward the …
– Lodestar
• Means Leading Star
– Aka North Star
• Discovered 1,000
years ago
Magnetic Poles
• The area of the
magnetic where the
magnetic effect is
strongest
• North Pole
• South Pole
Interactions Between Poles
• Like poles repel, Unlike poles attract
Breaking a Magnet
• Produces smaller magnets
Magnetic Fields
• The magnetic force
exerted all around a
magnet
• Magnetic Field Lines
– Spread out from one
pole, curve around the
magnet and return to
the other pole
– Never cross
Elements
• One of about 100
basic material that
make up all matter
• Atom
– The smallest particle
of an element
In an Atom
• Bigger, in Nucleus
– Protons
• “+” charge
– Neutrons
• No charge
• Electrons
– Small
– “-” charge
– Orbits nucleus
• Produce a small
“Atomic Magnetic
Force”
Magnetic Domain
• A cluster of billions of
atoms that have
magnetic fields that
are lined up in the
same way
• Magnetized Material
– All/most of the
domains are arranged
in the same direction
Ferromagnetic Material
• A material that shows
strong magnetic
effects
• Iron, Fe
• Nickel, Ni
• Cobalt, Co
Making Magnets
• Some materials can
be magnetized if
rubbed with a strong
magnet
– Typically just
temporary
• Magnetic Domains
become aligned
Destroying Magnets
• Knocking the domains • Drop it
out of alignment
• Strike it
• Heat it
MagLev
• 400 km/hr
– 250 mph
• Floats a few cm’s
above tracks
– No vibrations
– No noise from the
steel tracks