DC Motors
In a dc machines the residual magnetism is of the order of

50 to 75 percent
2 to 3 percent
10 to 15 percent
20 to 25 percent

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

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
Motor will run at very slow speed

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