Electrical Machines
Direction of rotation of DC motor is reversed by

 Reversing supply connection.
 Adding resistance to field circuit.
 Reversing armature connection or field connection.
 Interchanging armature and field connection.

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Electrical Machines
The mmf produced by rotor currents of a 3 - Φ induction motor

  rotates at the speed of rotor in the air gap.
  is at standstill with respect to stator mmf.
  rotates at slip speed with respect to stator mmf.
  rotates at synchronous speed with respect to rotor.

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