The working principle of the DC generator is to change the alternating electromotive force induced in the armature coil to direct electromotive force when it is drawn from the brush end.

The direction of the induced electromotive force is determined according to the right hand rule (the magnetic induction wire points to the palm, and the thumb points to the direction of motion of the conductor, then the other four fingers point to the direction of the induced electromotive force in the conductor).

The direction of the force on the conductor is determined by the left hand rule. This pair of electromagnetism creates a torque acting on the armature, which is called electromagnetic torque in the rotating motor. The torque is counterclockwise in an attempt to turn the armature counterclockwise. If this electromagnetic torque can overcome the resistance torque on the armature (such as resistance torque due to friction and other load torque), the armature can rotate counterclockwise.

Dc motor is a motor running on dc working voltage, which is widely used in recording machine, VCR, DVD player, electric shaver, hairdryer, electronic watch, toy, etc.