Although the mechanical construction of DC motors and generators is very similar, their functions are quite different. The function of a generator is to generate a voltage when the conductors move through a magnetic field, while an electric motor serves to produce a rotation effort, or torque, to produce mechanical rotation.
There is a magnetic field around a conductor conducting electric current. When this conductor is placed in another magnetic field, the two fields interact.
Magnetic fields in the operation of a motor never cross; The lines of the two fields accumulate on one side and cancel each other on the other side, producing, respectively, strong and weak fields.
ac motor vem31155 at mro supply
The interaction between the magnetic fields, main and the conductor of the armature, places the flow lines with the same direction, which tend to repel. Thus, the lines under the conductor when repelling, move the conductor upwards or, when the direction of the current in the conductor is inverted, to move it downwards.
The movement of the conductor causes it to cut the lines of the main magnetic field, according to Lenz’s law, opposing the movement that produced it.