Question

The wind speed required for the operation of a windmill is-

• A. 40 - 45 km/hr
• B. 30 - 35 km/hr
• C. 20 - 25 km/hr
• D. 10 - 15 km/hr

Hint:

Cut-in speed ≈ 10–15 km/hr, operating efficiency ≈ 20–25 km/hr, and cut-out speed (to stop turbine for safety) ≈ 40–50 km/hr.

Answer 1

The Correct Option is C

Step 1: Understanding windmill operation.
Windmills require a minimum wind speed (called cut-in speed) to start functioning and generating power.
Step 2: Ideal range for operation.
For most traditional windmills and small turbines, the cut-in speed is about 10–15 km/hr, but the efficient operational range is around 20–25 km/hr.
Below this, power generation is negligible, and above very high speeds, safety mechanisms stop the blades.
Step 3: Analysis of options.
- (1) 40–45 km/hr: Too high, usually unsafe for continuous operation.
- (2) 30–35 km/hr: High, but not the standard required speed range.
- (3) 20–25 km/hr: Correct, this is the typical operating range.
- (4) 10–15 km/hr: This is the starting speed, not the efficient operating speed.
Step 4: Conclusion.
Thus, the operational wind speed for windmills is 20–25 km/hr.