An electric train employing a dc series motor is running at a fixed speed, when a sudden slight drop in the mains voltage occurs. This would result in 

  • ADrop in speed and rise in current 
  • BRise in speed and drop in current
  • CRise in speed and rise in current
  • DDrop in speed with current unaltered 
Correct Answer : (A)

Drop in speed and rise in current 

Hints :

The current drawn by a 120 V dc motor with back emf of 110 V and armature resistance of 0.4 ohm is


With the increase in speed of a dc motor

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