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Unformatted text preview: History of Magnets
► Lodestone Magnetism Always pointed in one direction (North) –
aligned with Earth’s field
Magnetite Ch. 36 and 37 Types of Substances
can attract some non magnetic.
when placed in a
Iron, nickel, cobalt
►Non magnetic Magnetism
► Two poles North-Seeking
Opposite poles attract
► Like poles repel 1 Compass
► When placed in the Earth’s magnetic field: A bar magnet will align so that its north seeking
pole faces Geographic North.
A bar magnet will align itself so that its south
seeking pole faces Geographic South.
seeking Magnetic Domains
Clusters of atoms line up - electrons spin
in same direction.
► Microscopic clusters.
► Difference between regular iron and
magnetic iron is alignment of domains.
magnetic Magnetic Field Strength vs. Domain
Because magnetism is
produced by individual
atoms, the two poles
cannot be separated
(difference from charge).
(difference 2 To Make a Magnet
► By Contact Nail to magnet
► By Induction What was induction?
► By How to Demagnetize a Magnet
► Hammering Electricity “Electromagnets”
How do you think lodestones were
magnetized? Magnetic Fields Magnetic Fields ► Moves
North to South
► Strongest at
poles where field
► Exert force on
magnets) 3 Interaction of Magnetic Fields Motor
Converts Electrical Energy to Mechanical
► Consists of a
magnet, and an
Opposite Poles Like Poles Transformers Generator
► Electromagnetic Induction Producing current by moving a magnet
through a coil of wire.
Produces alternating current (AC)
Converts Mechanical Energy to
Electrical ► Increase
Increase or decrease voltage by
► Electricity carried over
long distances at a high
► “Stepped up” at power plant.
► “Stepped down” at house. 4 Transformers
► Power plant = 6000V
► Long distance transmission = 120,000V
► City transmission = 2200V
► Household Circuits = 120V 5 ...
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