1. 20.1 Magnetic Fields All magnets have two poles: N and S
Like poles repel and unlike poles attract
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2. 20.1 Magnetic Fields Geography & Magnetism Magnetic declination
Dip angle
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3. 20.1 Magnetic Fields
Dynamo model
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4. 20.1 Magnetic Fields
Dynamo model – field reversals, aurora, biomagnetism
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5. 20.1 Magnetic Fields
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6. 20.1 Magnetic Fields
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7. 20.2 Electric Currents produce Magnetic Fields
Hans Oersted (1820)
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8. F = I l B sinθ (if B is uniform)
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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9. 20.4 Force on Electric Charges in Magnetic Fields
F = q v B sinθ
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10. 20.4 Force on Electric Charges in Magnetic Fields
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11. 20.5 Magnetic Field of a Long, Straight Wire
The magnetic field strength is
if r << length of wire. r
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