The absence of which two components distinguishes AC induction motors?

• A. Brushes and armature
• B. Stator and rotor
• C. Windings and laminations
• D. Bearings and seals

Answer: (A)

Induction motors operate without a commutator or brushes. The stator’s rotating magnetic field induces current in the rotor, so no direct electrical connection to the rotor is needed. That means there’s no armature winding connected to a power source and no brushes to wear or spark. The rotor is typically a squirrel-cage or wound rotor with slip rings, but it remains electrically isolated from the supply. Because of this fundamental setup, the absence of brushes and an armature is what distinguishes AC induction motors from motor types that use a commutated armature. Other parts like the stator, rotor, windings, laminations, bearings, and seals are present in various motors, so they don’t uniquely identify induction motors.