Download 60 nm Scan Height - The University of Oklahoma Department

Magnetism: What you SHOULD know.
• What sticks (attracted) to magnets?
– Plastic, liquids like water, metals? -Do all metals stick?
– No Magnets are picky – iron containing materials (cobalt and nickel too)
– But plastics and liquids with iron in them are magnetic too
– And what are magnets or permanent magnets used to be iron containing but now exotic
• Magnets interacting with other magnets
– Can attract or repel!
– They have POLES North and South -like poles repel, opposite poles attract
– All magnets have a north and south pole, break a magnet and the pieces have north an south
poles too!
– Compass has magnet at the end of a needle and it is attracted to other magnets and the
Earth is one BIG magnet.
• Magnetic Patterns or Fields
– Lines of Force (called field lines) trace out the direction a small magnet would point
– Can use iron filings to show these Lines of Force (field lines) –they start and end on the
magnet!
– The Earth’s north pole is actually a magnetic South pole!!
– Magnetism goes through (penetrates) non-magnetic material.
• Electricity makes a magnetic field
– Many loops (a coil) around a nail can make a strong electro-magnet
– Information (music) can be stored using electricity to make permanent magnets on a tape
• Magnets can make electricity
– Move a magnet in a coil and current is generated
– Generator motion makes electricity/ Motor electricity makes motion
Magnetism: What you DON’T know.
– fun with strong magnets
• Actually magnets can effect more than just iron containing material!
• Magnets with all metals – Eddy current
– A moving magnet (1) makes a current in a stationary metal, but current makes a magnet
(2)! And magnets interact!
– Interaction acts to slow (damp) the magnet.
• Magnets weakly attract nearly all non-iron containing materials – PARAmagnetism
– Always attractive
– Oxygen, O2, (even liquid oxygen) is paramagnetic.
• Magnets very weakly repel a small number of materials – DIA-magnetism
– Always repel and this can make levitation!!
– Materials include graphite (aka pencil lead); water (frogs and strawberries too).
– The effect is particularly strong in superconductors!
– And this can be made to levitate a train!!
• Other fun levitation schemes.
– Active control
– Mechanical constraint
Magnetism: What you SHOULD know. (I)
• What sticks (attracted) to
• Dip the magnet into a
magnets?
bucket of different
–Plastic, liquids like water,
objects - What sticks?
metals? -Do all metals stick?
– Coins, plastic, wood,
–No Magnets are picky – iron
nails, water, etc.
containing materials (cobalt
• Show plastic magnets and
and nickel too)
ferrofluid.
–But plastics and liquids with
iron in them are magnetic too • Show neat magnets, balls,
super strong, refrigerator
–And what are magnets or
etc.
permanent magnets used to be
iron containing but now exotic
• Show repulsion
• Magnets interacting with other
attraction.
magnets
–Can attract or repel!
– Break a magnet and
–They have POLES North and
show they always
South -like poles repel,
have a north and
opposite poles attract
south.
–All magnets have a north and
– Play with a compass.
south pole, break a magnet
and the pieces have north an
south poles too!
–Compass has magnet at the
end of a needle and it is
attracted to other magnets and
the Earth is one BIG magnet.
Magnetism: What you SHOULD know. (II)
• Magnetic Patterns or Fields
–Lines of Force trace out the
direction a small magnet
would point
–Can use iron filings to show
these Lines of Force
–Earth’s north pole is actually
a magnetic South pole!!
–Magnetism goes through
material.
• Electricity makes a magnetic
field
–A coil around a nail can
make a strong electromagnet
–Music can be stored using
electricity to make
permanent magnets on a
tape
• Magnets can make electricity
–Move a magnet in a coil and
current is generated
–Generator motion makes
electricity/ Motor electricity
makes motion.
• Magnetic Patterns or Lines
of Force or Fields
– Use magnets
– Use iron filings
– Use 3D demo
– Use magnerite
• Electricity makes a
magnetic field
– Field pattern near wire
or loop
– Show electromagnet
• Magnets can make
electricity
– Move magnet near wire
or coil.
– Show handcrank
generator
Magnetism: What you DON’T know. (I)
– fun with strong magnets
• Actually magnets can effect • Eddy Current
more than just iron
– Magnetic/ non magnetic ball
containing material!
bearing down a metal/plastic tube.
– Move magnet over a copper plate.
• Magnets with all metals –
Eddy current
–A moving magnet (1) makes
a current in a stationary
metal, but current makes a
magnet (2)! And magnets
interact!
–Interaction acts to slow
(damp) the magnet.
• Magnets weakly attract
nearly all non-iron
containing materials –
PARA-magnetism
–Always attractive
–Oxygen, O2, (even liquid
oxygen) is paramagnetic.
• Magnets weakly attract PARAmagnetism
– Aluminum bar on a string with
strong magnets on a turntable
– Liquid O2 dripped on strong
magnet.
Magnetism: What you DON’T know. (I)
– fun with strong magnets
• Magnets very weakly
repel a small number of
materials – DIAmagnetism
– Always repel and this
can make levitation!!
– Materials include
graphite (aka pencil
lead); water (frogs
and strawberries too).
– The effect is
particularly strong in
superconductors!
– And this can be made
to levitate a train!!
• Other fun levitation
schemes.
– Active control
– Mechanical constraint
• Magnets very weakly
DIA-magnetism
– Always repel and can
levitate
– Materials include
graphite (aka pencil
lead); water (frogs and
strawberries too).
– The effect is
particularly strong in
superconductors!
– And this can be made
to levitate a train!!
• Other fun levitation
schemes.
– Active control
– Mechanical constraint
Magnetism: What you DON’T know. (I)
– fun with strong magnets
• Magnets very weakly repel a
small number of materials –
DIA-magnetism
–Always repel and this can
make levitation!!
–Materials include graphite
(aka pencil lead); water (frogs
and strawberries too).
–The effect is particularly
strong in superconductors!
–And this can be made to
levitate a train!!
• Other fun levitation schemes.
–Active control
–Mechanical constraint
• Magnets very weakly DIAmagnetism
• Eddy Current
– Magnetic/ non magnetic ball
bearing down a metal/plastic tube.
– Move magnet over a copper plate.
• Magnets weakly attract PARAmagnetism
– Aluminum bar on a string with
strong magnets on a turntable
– Liquid O2 dripped on strong
magnet.