AC motors are usually brushless and rely on electromagnetic induction.

• A. The rotor uses permanent magnets
• B. Usually brushless and rely on electromagnetic induction
• C. Require a DC supply
• D. Have more wear due to brushes

Answer: (B)

AC motors that you’ll usually encounter are brushless and operate on electromagnetic induction. The stator is powered with alternating current, creating a rotating magnetic field. The rotor has conductors in which currents are induced by that changing field, and these induced currents generate their own magnetic field that interacts with the stator field to produce torque. Because there are no brushes in this setup, wear from brushes is minimized. The other statements don’t fit the typical design: many AC motors don’t use permanent magnets in the rotor, they’re driven by AC (not DC), and the brushless construction means there isn’t significant wear from brushes.