ATAR Notes: Forum
VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Physics => Topic started by: physics on October 15, 2010, 09:36:26 pm
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If thye ask the average EMF?
DO we use the turn for a whole cycle or do we use the time from maximum to minium which would be a quarter of the period as the time?
eg. Find the average induced EMF of..
IF 1 revolution takes 4 seconds
would the time be 4 seconds or 1 second?
AND for those graphs where a rectangle coil is moving into a field and out the field?
how do we work out the induced current created when it is moving in? do we calucalte the time for the coil to have no flux(outside) to when it is at maximum flux(inside the field)
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with your first question it does depend on the question, its not always a quarter of a turn. But yes with your example you would do change in magnetic flux / 1. Which would be maximum magnetic flux / 1
With your second question are you referring to the magnitude or direction of the current?
usually if your drawing a graph, find the peak value for the current , which will be determined by the peak induced EMF and then use V=IR.
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take a quarter of a period. (ie from maximum to zero, or vice versa)
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average emf is always the same, no matter if you do a full turn or quarter turn. thats why its an average.
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umm its not always a quater turn actually. For example say you only rotate a coil by 1/6th of its period. It hasnt even reached is possible maximum induced EMF. therefore the average emf induced within it wont be calculated by using a quater of the period.
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umm its not always a quater turn actually. For example say you only rotate a coil by 1/6th of its period. It hasnt even reached is possible maximum induced EMF. therefore the average emf induced within it wont be calculated by using a quater of the period.
That it'd be a pain in the ass to work out!
determining the flux when the armatures on an angle... get the trig happening. I doubt they'd make us do that...
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you know when we have the mag field and the thing moves at a velocity of whatevr then the change (or avergae flux) would be from when it is outside to completely inside
NOT from when its completely outside then at the other end right????
someone help :(((((
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you know when we have the mag field and the thing moves at a velocity of whatevr then the change (or avergae flux) would be from when it is outside to completely inside
NOT from when its completely outside then at the other end right????
someone help :(((((
yes its from outside to completely inside. Because once it is completely immersed, there is no change in flux
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you know when we have the mag field and the thing moves at a velocity of whatevr then the change (or avergae flux) would be from when it is outside to completely inside
NOT from when its completely outside then at the other end right????
someone help :(((((
yes its from outside to completely inside. Because once it is completely immersed, there is no change in flux
those questions are confusing.
so avreage EMF is from min to max.
the -ve symbol in the equation doesnt matter right?
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you know when we have the mag field and the thing moves at a velocity of whatevr then the change (or avergae flux) would be from when it is outside to completely inside
NOT from when its completely outside then at the other end right????
someone help :(((((
yes its from outside to completely inside. Because once it is completely immersed, there is no change in flux
those questions are confusing.
so avreage EMF is from min to max.
the -ve symbol in the equation doesnt matter right?
yea you dont really need to worry about that, all it indicates is that the direction of the induced emf is opposite to the change in flux.
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but its not part of the formula?
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but its not part of the formula?
when your calculating values for emf dont worry about the - sign.
when your drawing a graph of emf , make sure its the negative rate of change on the graph of magnetic flux.
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example please :D