Back EMF and Current Variability: A Puzzling Question

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SUMMARY

The discussion centers on the relationship between back electromotive force (EMF) and current variability in electric motors. Participants highlight that while the back EMF is treated as constant in the equation E=Ir+E', both the current and the area through which the magnetic field lines cut are variable. The inconsistency arises from the assumption that the magnetic field remains constant, which contradicts the dynamic nature of the motor's operation as the loop rotates.

PREREQUISITES
  • Understanding of back electromotive force (EMF) in electric motors
  • Familiarity with the equation E=Ir+E' in electrical circuits
  • Knowledge of magnetic fields and their interaction with conductive loops
  • Basic principles of motor operation and rotational dynamics
NEXT STEPS
  • Research the principles of back EMF in DC motors
  • Study the effects of variable magnetic fields on motor performance
  • Explore the relationship between current and torque in electric motors
  • Learn about the dynamics of rotating loops in magnetic fields
USEFUL FOR

Electrical engineers, motor control specialists, and students studying electromagnetism and motor dynamics will benefit from this discussion.

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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