Electrical Machines
In a DC machine the armature mmf is

 rotating with respect to field poles.
  rotating with respect to field poles as well as armature.
  stationary with respect to field poles.
  stationary with respect to armature.

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
The introduction of interpoles in between the main poles improves the performance of a dc machine, because

 the flux waveform is improved with reduction in harmonics
 the interpoles produce additional flux to augment the developed torque
 the inequality of air-gap flux on the top and bottom halves of the armature is removed
 a counter-emf is induced in the coil undergoing commutation

ANSWER DOWNLOAD EXAMIANS APP