9.What will happen if we give AC supply to DC motor, and vice versa

When A.C. supply is given to a D.C. motor, 1)In case of Series connection of armature winding and field winding , it may run. 2)But, In case of parallel connection , it won't rotate at all and will start humming and will create vibrations, as a torque produced by positive and negative cycle will cancel out each other. D.C. motor will be heated up. When D.C. supply is given to an AC. motor , 1) D.C. supply will not produce rotating magnetic field , hence motor will not run. 2) If rated voltage is given (in D.C. form), there will be only resistance of the winding will affect the D.C. current , whereas in case of a.c. supply, impedance will affect the A.C. current. Now, resistance of winding will always be less than total impedance. Hence, larger amount of current will flow (with compare to A.C. current) through the winding and will damage the winding.