Working principle of a DC motor

The working of DC motor is based on the principle that when a current-carrying conductor is placed in a magnetic field, it experiences a mechanical force.
The direction of mechanical force is given by Fleming’s Left-hand Rule and its magnitude is given by F = BIl Newton.
There is no basic difference in the construction of a DC generator and a DC motor. In fact, the same d.c. machine can be used interchangeably as a generator or as a motor. Like generators DC motors are also classified in to shunt-wound, series-wound and compound-wound.