Rotating blades or "________" form the steam flow passages in impulse turbines.

• A. Buckets
• B. Pails
• C. Ports
• D. Diaphragms

Answer: (A)

In impulse turbines, energy transfer comes from the momentum change of steam as it hits the rotor blades. The rotating blades on the rotor are called buckets, and they form the steam flow passages on the wheel. Steam is first directed through stationary nozzles to accelerate it, then it strikes the buckets, and their shape guides the steam around while extracting energy to turn the shaft. The term buckets fits because these blades are the moving part that actually carries the flow path. Other terms don’t describe the rotating flow path: ports are just openings, diaphragms are stationary components that shape flow in other turbine designs, and pails isn’t a technical term.