Electrical Machines
In dc machines, the field system has to be provided on stator unlike synchronous machines Where in it could be on any member, because

 it reduces field structure iron losses
 it gives more uniform air-gap flux distribution
 dc machines are comparatively low rating machines.
 commutator action is not possible otherwise

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
When the supply terminal of a DC shunt motor are interchanged

 The motor will stop.
 The motor will run much faster in the same direction.
  The motor will run at its normal speed in the same direction as before.
 The direction of rotation will reverse.

ANSWER DOWNLOAD EXAMIANS APP