Electrical Machines
The oscillation in a synchronous motor can be damped out by

  providing damper bars in the rotor pole faces.
  running the motor on leading power factors.
  oscillation cannot be damped.
  maintaining constant excitation.

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
Flashing of DC generator means

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

ANSWER DOWNLOAD EXAMIANS APP