Which components are absent in AC induction motors?

• A. Armature and brushes
• B. Stator windings and rotor bars
• C. Carbon brushes only
• D. Armature only

Answer: (A)

Induction motors rely on electromagnetic induction between a stator that creates a rotating magnetic field and a rotor that converts that field into motion. The rotor in a typical AC induction motor is not connected to the power supply; it is a closed conductor (often a squirrel-cage of bars and end rings) that carries induced current driven by the stator’s field. Because there is no direct electrical connection to the rotor and no commutator, there is no need for armature windings fed by the supply and no carbon brushes to transfer current. That makes armature and brushes absent in AC induction motors.

The motor does have stator windings to generate the rotating field and rotor bars or windings to respond to it, so those parts are present. In some wound-rotor designs, slip rings and brushes can appear, but the standard induction motor most commonly discussed uses no armature or brushes at all.