Electrical Machines
DC generator will not build up voltage

 due to wrong direction of rotation.
 if field resistance is more than critical resistance.
 any one of above.
  if it has lost residual magnetism.

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
Flashing of DC generator means

 neutralization of residual magnetism.
  creation of residual magnetism by a DC source.
  increasing flux density by providing extra ampere-turns in field.
None of these

ANSWER DOWNLOAD EXAMIANS APP