Electrical Machines
Commutation in a DC machine may be explained as a process

  by which electric current in a coil is reversed.
 how alternate flux affects the main field flux.
 by virtue of which emf is induced in the armature conductors.
  in which magnetic field is set up.

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
For an ideal transformer the winding should have

 equal resistance on primary and secondary side
 maximum resistance on primary side and least resistance on secondary side
 minimum resistance on primary side and maximum resistance on secondary side
 no ohmic resistance on either side

ANSWER DOWNLOAD EXAMIANS APP