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magnetism - Coggle Diagram
magnetism
motor effect
if the current is reversed or the magnetic field is reversed, the force will be reversed
if the magnitude of the current or of the magnetic field is increased, the magnitude of the force will increase
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DC motors
direct current flows through the wire and it experiences a tuyrning effect due to the force exerted on it
as current flows in opposite directions on each side of the coil, the forces on each side are in opposite directions, making it turn
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a split ring commutator is used to ensure that the direction of the current reverses every half a turn
transformers
a transformer consists of two coils wrapped around a soft iron core and is used to change the size of the voltage
they are used to
step up the voltage for transmission in power lines which reduces power loss (because lower current causes less power loss due to the resistance of the cables
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an alternating voltage produces an alternating current in the primary coil. this creates a changing magnetic field which links with the secondary coil and induces and alternating voltage in it
a step-up transformer has more turns on the secondary coil and induces and alternating voltage in it
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magnetic field patterns
flat, circular coil
circular around the wire, with a straight line between the wire
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wire
use the right hand grip rule to determine the direction of the magnetic field produced by a current carrying wire
generator effect
coil rotates, meaning the wire experiences a changing magnetic field strength, which indices p.d across a wire which induces a current if the circuit is complete
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a voltage is induced in a conductor or a coil when it moves through a magnetic field or when a magnetic field changes through it
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2 permanent magnets have poles and there is a uniform magnetic field between the opposite poles of two magnets placed close together. The field lines are parallel and evenly spaced
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there is a force on a charged particle when it moves in a magnetic field as long as its motion is not parallel to the field
electromagnets consist of a coil of wire wrapped around a magnetically soft core and can be turned on and odd