The working principle of the Dynamo is induced in the armature coil an alternating electric potential,
Commutator brush of the tie in reversing roles, so that when drawn from the brush into the principles of DC electric potential.
EMF direction determined by the right-hand (magnetic field lines point to the Palm of the hand, thumb pointing in direction of motion of the conductor, it points to is the conductor of the other four fingers in the direction of the induced electromotive force).