Electrical Machines
In a loaded DC generator, if the brushes are given a shift from the interpolar axis in the direction of rotation, then the commutation will

 improve with fall of terminal voltage.
 improve with rise in terminal voltage.
 deteriorate with rise in terminal voltage.
 deteriorate with fall of terminal voltage.

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Electrical Machines
A 3-φ alternator has negligible stator resistance. A short circuit test is conducted on this alternator. At a particular speed, a field current of If1 is required to drive the rated armature current. If the speed of the alternator is reduced to half, the field current required to maintain rated armature current

 Would be equal to If1/2.
 Would be equal to If1.
  Cannot be predicted due to insufficient data.
 Woud be equal to 2If1.

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