If the commutator assembly loosens, what pushes the mica outward?

• A. Centrifugal Force
• B. Gravity
• C. Magnetic Force
• D. Thermal Expansion

Answer: (A)

When the rotor is spinning, components mounted on it experience an outward pull called centrifugal force. The mica sheets between the commutator and the other parts are lightweight and rely on the clamp that holds them in place. If the commutator assembly loosens, this outward inertia from rotation tends to push the mica outward, away from the center, especially at higher speeds and larger radii. The magnitude grows with mass, radius, and angular speed (F ≈ m r ω^2), so the loose setup makes the mica more likely to be pushed outward. Gravity acts downward and is negligible in this rotating, outward-pushing context, magnetic force isn’t the outward driver in this mechanical situation, and thermal expansion would require heating and isn’t the immediate cause of a outward movement when the assembly loosens. Therefore, centrifugal force is the force doing the pushing.