How a rotaing magnetic field is generated in an induction motor?

The magnet is the stator part of the motor, either as a permanent or an electromagnet. It draws the rotor past of the motor towards it causing the rotation. As it does this the brushes of the motor now lose contact with that section of the rotors many coils and switch to next segment on the commutator (copper segments the brushes run on). This new coil becomes magnetised and is again drawn to the stator magnet and so on.