Working Principal Of DC Motor

When a current-conducting conductor is placed in a magnetic field, it experiences a torque and due to which it has a tendency to rotate. In other words, when a magnetic field and an electric field interact, a mechanical force is produced. A DC motor or direct current motor works on this principle. This is known as motoring action.
The direction of rotation of this motor is given by Fleming's left hand rule, which states that if the index finger, middle and thumb of your left hand are stretched mutually perpendicular to each other and if the index finger represents the direction of the magnetic field , The middle finger indicates the direction of current flow, the thumb indicates the direction of the rotating force that the force is experienced by the shaft of the DC motor.

Structurally and construction wise a D.C. Motor and a D.C. generator Similar, but electrically it is the exact opposite. Here, unlike a generator, we supply electrical energy to the input port and receive mechanical energy from the output port. We can represent this by the block diagram shown below.

Here in a DC motor, the supply voltage E and current I are given to the electrical port or input port and we get the mechanical output i.e. torque T and speed  ω from the mechanical port or output port.