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

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

A.            nothing will happen to the motor

B.            this will make armature to take heavy current, possibly burning it

C.            this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses

D.            motor will run at very slow speed

Answer: this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses