DC Motors
The value of back emf in dc motor is maximum at

No load
Full load
Half full load
None of the listed here

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

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

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

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

ANSWER DOWNLOAD EXAMIANS APP