Answer / rahul ganthade

It depends on whether the field winding of the dc motor is
connected in series or in shunt with the armature
winding.If it is connected in series,the motor will rotate
since the torque,which varies as the product of the
armature and field current is always positive.Thus,a
positive average torque causes the motor to rotate,however
the pulsating nature may cause the commutator segments and
brushes to wear out.
Thus only small sized dc motors may be used with ac supply.

Answer / rafi

Yes, it is possible,

irrespective of ac or dc, the current flowing at any point
of time in the rotor and stator in dc motor will produce
the torque in same direction.

try reversing the polarity of DC supply for a dc motor, it
will rotate in same direction. Applying AC supply is
similar to reversing the supply polarity 50 times in a sec.
so even if you apply AC the motor will run in same
direction.

I hope this clarifies the query

sir please send me previous year questions of jspl of electrical section through which i could prepare myself fpr the test.

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