Electrical Machines
Cogging of induction motor occurs at

 high voltage and when stator and rotor poles are equal.
 high voltage and when stator and rotor poles are not equal.
 low voltage and when stator and rotor poles are equal.
 low voltage and when stator and rotor poles are not equal.

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Electrical Machines
In a 3 - Φ induction motor

  none of them.
  power factor at starting in the same as that while running.
  power factor at starting is low as compared to that while running.
  power factor at starting is high as compared to that while running.

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Electrical Machines
With the increase in speed of a DC motor

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

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