Electrical Machines
With the increase in speed of a DC motor

 both back emf as well as line current fall.
 both back emf as well as line current increase.
 back emf increases but line current falls.
 back emf falls and line current increases.

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Electrical Machines
In a synchronous motor when the rotor speed exceeds the synchronous speed during hunting

  negative sequence currents are generated.
  the damper bars develop induction motor torque.
  the damper bars develop induction generator torque.
  the damper bars develop synchronous motor torque.

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Electrical Machines
In dc machines, the field system has to be provided on stator unlike synchronous machines Where in it could be on any member, because

 commutator action is not possible otherwise
 it reduces field structure iron losses
 it gives more uniform air-gap flux distribution
 dc machines are comparatively low rating machines.

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