Electrical Machines
Alternator operates on the principle of

  electromagnetic induction.
  mutual induction.
  self or mutual induction.
  self induction.

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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

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

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