Explain why a motor must use a commutator if only DC current is supplied.
Current must be applied to the armature (rotor).
an AC motor can operate on oscillating electromagnetic fields which induce currents in coiled wire. DC motors not not operate with such induced fields. Instead they must create therir own oscillating fields in the coils and this is done by rapidly switching the current on and off. This switching is done by means of the comutator and the split electrodes on the shaft...Hope this helps...
