The working principle of a DC generator is to convert the alternating electromotive force induced in the armature coil into a direct current electromotive force when it is led out from the brush end through the commutator and the commutation action of the brush.

The direction of the induced electromotive force is determined according to the right-hand rule (the magnetic induction line points towards the palm of the hand, the thumb points towards the direction of the conductor's movement, and the direction of the other four fingers is the direction of the induced electromotive force in the conductor).

Working principle of DC motor

The direction of force on a conductor is determined using the left-hand rule. This pair of electromagnetic forces forms a torque acting on the armature, which is called electromagnetic torque in a rotating motor. The direction of the torque is counterclockwise, attempting to cause the armature to rotate counterclockwise. If this electromagnetic torque can overcome the resistance torque on the armature (such as resistance torque caused by friction and other load torques), the armature can rotate counterclockwise.

DC motors are motors that rely on DC operating voltage and are widely used in recorders, video recorders, DVD players, electric shavers, hair dryers, electronic watches, toys, and more.