Electrical Machines
For a given torque, reducing divertor resistance of a DC series motor

  Decrease in speed but armature current remains the same.
  Decrease in speed demanding less armature current.
  Increase in speed but armature currnet remains the same.
  Increase in speed demanding more armature current.

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Electrical Machines
With the increase in speed of a DC motor

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

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