What is the effect of air passing over the turbine blades?

• A. It cools the turbine blades.
• B. It diverts air away.
• C. It slows the turbine.
• D. It blows the air over the turbine blades, causing them to spin.

Answer: (D)

Air moving past the turbine blades transfers energy to them, pushing on the blades and creating a turning force. The blades are shaped and angled so that this force converts the air’s kinetic energy into rotational energy, making the rotor spin. That spinning motion is how the turbine extracts energy from the moving air to drive the rest of the system. Other options don’t describe this energy transfer—cooling, diverting air, or a slowing effect aren’t the primary action of air flow on the blades.