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15 Cards in this Set
- Front
- Back
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How do you calculate force of an electron in a magnetic field ?
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F=BQV
B= flux density Q= Charge V= velocity |
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What unit is flux measured in ?
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Wb or weber
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What is the unit for flux density ?
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Tesla
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What is magnetic flux density – definition ?
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This is the magnitude and direction of a field at a certain point .
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Equation for flux density ?
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B= Flux / Area
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What is the equation for flux linkage ?
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N θ
N= number of turns Θ = magnetic flux |
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What happens when rate of change of flux = 0 ?
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Emf induced = 0
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What is the relationship between current and flux ?
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(Rate of change of) flux is proportional to (rate of change of ) current
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What does the laminated core do ?
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Reduces eddy currents ( therefore less energy loss)
Therefore increase in magnetic flux |
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what is lenz's law ?
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The current flows so that it opposes the change in magnetic flux by creating its own magnetic field
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what does lenz's law introduce ?
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lenz's law introduces the minus sign in the equation
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how does a transformer work ?
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- current flowing through primary coil creates an alternating current throughout the transformer .
- Alternating current links with secondary coil inducing an alternating emf in secondary coil - lenses law means that this would be 180 degrees out of phase |
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what are eddy currents ?
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-these are inducing electrical currents around the flux lines within the core itself
- make iron hot plus waste energy - have a circular magnetic field |
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what is permeance ?
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permeance is the measure of the quantity of flux for a measure of current turns in a given magnetic circuit
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equation for permeance ?
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