DC Motors
If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens

This will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses
Nothing will happen to motor
This will make armature to take heavy current, possibly burning it
Motor will come to stop

ANSWER DOWNLOAD EXAMIANS APP

DC Motors
If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens

Nothing will happen to the motor
This will make armature to take heavy current, possibly burning it
Motor will run at very slow speed
This will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses

ANSWER DOWNLOAD EXAMIANS APP