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PHYSICS UNIT 8 - MAGNETISM & ELECTROMAGNETISM (Magnetic Poles &…
PHYSICS UNIT 8 - 
MAGNETISM & ELECTROMAGNETISM
Magnetic Poles & Field Lines
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Can show magnetic field by drawing magnetic field lines - always go from north to south & show which way a force would act on a north pole if it was put at that point in the field
Induced & Permanent - When piece of unmagnetised magnetic material touches or brought near to the pole of a permanent magnet, it becomes a magnet itself. The magnetism is "induced". When take away magnetic field, induced magnets lose most or all magnetism.
All magnets produce magnetic field - a region where other magnets or magnetic materials (e.g.. iron, steel, nickel & cobalt) experience a force
Attraction & Repulsion
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Compass & Earth's Magnetic Field
Pole of the compass needle which points North is a South magnetic pole as it has to be in order to to be attracted to point North!
Compass provides evidence that Earth has magnetic field so Earth's core must be magnetic - electric currents generated in conductive material of its core (liquid iron).
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Motor Effect
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When current-carrying wire put between magnetic poles the wire's magnetic field interacts with the other magnetic field which creates a force = motor effect
Fleming's Left Hand Rule
Find direction of the force
Right Hand Grip Rule
Point right hand thumb in direction of current & curl fingers. direction of fingers is the direction of the magnetic field.
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Electromagnets
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The field lines around each loop line up with each other so lots of fields pointing in same direction close to each other.
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Can increase the field strength by putting block of iron in the centre of the coil which becomes an induced magnet when current flowing.
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Electric Motor (favourite exam topic)
Because coil on an axle and the forces act one up and one down, it rotates
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