can dc current be supplied to an ac motor?
Yes if it is a shunt wound universal motor. These are the type with an armature and carbon brushes. If it is an induction motor then the answer is no.
Common DC motors will not work on AC. This is because they contain permanent field magnets and are reversible by reversing the polarity of the applied current. Since AC reverses 60 times per second, the motor will try to follow the reversals, but will end up not turning at all, or perhaps buzzing a little bit. Also, it will overheat quickly in this state. It is easy to change an AC power source to DC by inserting a diode or rectifier in series with the motor and AC source, but the AC voltage must match the DC voltage rating of the motor fairly closely. A transformer may be needed ahead of the rectifier to reduce the voltage if house current is to be used. The diode used must be rated to handle the maximum voltage and peak current expected. (This will depend on the motor load.) Also, the motor brushes may develop high voltage spikes that can damage the rectifier, so it is a good idea to add a capacitor across the motor to absorb these. There is a type of motor called a universal motor or an AC/DC motor that will run on AC or DC (usually the DC voltage required is lower than the AC required). These motors have no permanent magnets, using instead an electromagnetic field coil. The reason these work on AC is because the field coil polarity reverses along with the armature coil when the AC source reverses, keeping the attraction between the two coils in the same direction. Most portable power tools and vacuum cleaners contain these motors, although they aren't intended to ever run on DC.
A dc current can only be supplied from a battery or powerpack and you cant put the opposite current into a device which requires the other current. Therefore you cant supply dc current to an ac motor
