What effect does increased surface area have on air cooling for the rotor?

Increased surface area enhances air cooling for the rotor by providing more space for air to come into contact with the rotor's surface. This larger area allows for more effective heat dissipation, as the air molecules can transfer heat away from the rotor more efficiently. When there's more surface area, there's a greater opportunity for air movement to cool the rotor through convection. This principle is especially relevant in performance applications where managing heat is crucial for maintaining optimal performance and preventing overheating.

While the other choices suggest various effects, they do not capture the enhanced heat exchange capabilities tied to an increased surface area. By improving the air cooling efficiency, the rotor can operate at lower temperatures, leading to improved performance and durability.