Which of the following statements aligns with the absence of brushes or armature in AC induction motors?

• A. They are fitted with carbon brushes
• B. They require an external motor drive
• C. They use a commutator
• D. They have no brushes or armature

Answer: (D)

Induction motors operate with a rotating magnetic field in the stator that induces current in a rotor that is not electrically connected to the supply. Because the rotor currents are induced rather than fed directly, there is no commutator and no brushes or armature on the machine. This fundamental setup is what makes the absence of brushes or armature the correct description. Carbon brushes and a commutator belong to motors where power is transferred to the rotor through contact, such as brushed DC or universal motors, and an external drive is only required in some setups for speed control, not a defining feature of induction motors. So the statement that they have no brushes or armature best reflects how AC induction motors actually operate.