Back EMF and Current Variability: A Puzzling Question

AI Thread Summary
The discussion centers on the relationship between back EMF and current variability in motors. It questions the assumption that back EMF can be treated as a constant when current is not constant. The argument is made that if the magnetic field is constant, the back EMF should also vary due to changes in the area through which the magnetic field lines pass as the loop rotates. The equation E=Ir+E' is scrutinized, with E' and resistance r considered constants. Overall, the conversation highlights the complexities of back EMF in relation to changing current and magnetic field interactions.
brainyman89
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while solving an exercise, i have found that they are considering the back emf of a motor constant although the current is not constant? how comes that? shouldn't it be variable as current varies?
they are considering that as E=Ir+E' where E' and r are constants?
 
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If the magnetic field is constant then I don't see how the back emf could be constant. It will be determined by the size of the area which the magnetic field lines 'cut', and this will obviously be changing as the loop rotates.
 
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