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20.1 Magnetic Fields All magnets have two poles: N and S Like poles repel and unlike poles
attract
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20.1 Magnetic Fields
Geography & Magnetism
Magnetic declination
Dip angle
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20.1 Magnetic Fields Dynamo model
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20.1 Magnetic Fields Dynamo model – field reversals, aurora,
biomagnetism
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20.1 Magnetic Fields
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20.1 Magnetic Fields
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20.2 Electric Currents produce Magnetic Fields Hans Oersted (1820)
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20.3 Force on Electric Currents in Magnetic Fields
The direction of the magnetic force is always perpendicular to both I and B.
F = I l B sinθ (if B is uniform)
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20.4 Force on Electric Charges in Magnetic Fields
F = q v B sinθ
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20.4 Force on Electric Charges in Magnetic Fields
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20.5 Magnetic Field of a Long, Straight Wire
The magnetic field strength is
if r << length of wire.
r
IB o
2
r