magnetic flux density x cross sectional area perp to magnetic field
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What is magnetic flux measured in? define it
WEBBER/ magnetic flux density 1T passing normally through an area of 1m2
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What is magnetic flux linkage? what is it measured in?
product of magnetic flux and n of turns of a conductor/ webber
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What is Faradays Law?
induced emf is prop ro the rate of change of magnetic flux linkage/ emf = NBA/t
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How else can emf be found?
flux linkage vs time graph is the gradient // BLvN
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What is Lenz law? what is it a product of?
the direction of induced emf or current is such that to oppose the change producing it (-NBA/t)
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Explain Lenz's Law
work it does to push the magnet into the coil against the repulsive force/ the energy resulting from the work is transferred into electric energy of the current
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Describe the function of an AC generator
convert kinetic energy into electrical energy/ rotation of coil induces emf across ends of the coil/ slip ring and brushes allow circuit to remain complete - ac current
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what is the maximum induced emf depend on?
directly prop to / frequency of rotation/ B/ N/ A
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describe the structure of transformers
two coils of insulted wire wound around laminated soft iron core
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Describe how a transformer works
alternating current of primary coil produces a changing magnetic field/ changing field links to secondary/ change in the rate of magnetic flux linkage/ induces emf in secondary
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Describe a step up transformer
Vs is bigger than Vp/ Ns is bigger than Np/ low to high voltage
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Describe a step down transformer
Vp bigger than Vs/ more turns on primary/ high to low volatge
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Why are transformers used?
electricity from power station sent around on grid at lowest possible current so less is los to resistance/ Power = IV low current high voltage
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Other cards in this set
Card 2
Front
What is magnetic flux measured in? define it
Back
WEBBER/ magnetic flux density 1T passing normally through an area of 1m2
Card 3
Front
What is magnetic flux linkage? what is it measured in?
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