Wind turbines convert wind kinetic energy into what?
A Solar heat
B Electrical power
C Hydraulic pressure
D Chemical fuel
Answer: B. Electrical power. The rotor captures wind energy and drives an electrical generator.
Available wind power varies approximately with wind speed to what power?
A First power
B Second power
C Fourth power
D Third power
Answer: D. Third power. Wind power is proportional to the cube of wind speed for fixed area and density.
Betz limit is the theoretical maximum fraction of wind power captured, about what?
A 25 percent
B 59.3 percent
C 75 percent
D 100 percent
Answer: B. 59.3 percent. The Betz limit is 16/27, approximately 59.3 percent.
A wind turbine rotor consists of hub and what?
A Blades
B Solar cells
C Guide vanes only
D Fuel injectors
Answer: A. Blades. Blades extract energy from wind and turn the hub.
Yaw control turns the rotor to face what?
A Grid frequency
B Wind direction
C Ground slope
D Blade pitch only
Answer: B. Wind direction. Yaw systems orient the nacelle and rotor toward the wind.
Pitch control changes blade angle to regulate what?
A Tower height
B Grid voltage only
C Aerodynamic power
D Foundation depth
Answer: C. Aerodynamic power. Blade pitch adjusts aerodynamic capture and limits power at high winds.
Cut-in speed is the wind speed at which turbine begins what?
A Maximum output
B Shutdown
C Yaw rotation only
D Power generation
Answer: D. Power generation. Below cut-in speed, available wind power is insufficient for generation.
Rated wind speed corresponds to what turbine output?
A Cut-out condition
B Zero output
C Maximum blade angle always
D Rated power
Answer: D. Rated power. At rated wind speed the turbine reaches its rated electrical output.
Cut-out speed triggers what turbine action?
A Maximum power increase
B Battery charging
C Shutdown for protection
D Blade extension
Answer: C. Shutdown for protection. Very high wind speeds can cause protective shutdown.
Wind-farm capacity factor compares actual generation with what?
A Turbine mass
B Rated generation potential
C Blade length
D Grid voltage
Answer: B. Rated generation potential. Capacity factor is actual energy divided by energy at continuous rated output.
Tip-speed ratio compares blade tip speed with what?
A Generator frequency
B Tower height
C Rotor radius
D Wind speed
Answer: D. Wind speed. Tip-speed ratio λ = blade-tip speed divided by wind speed.
A wind turbine generator converts shaft rotation into what?
A Electrical energy
B Hydrogen
C Compressed air
D Thermal storage
Answer: A. Electrical energy. The generator converts mechanical rotation into electricity.
A gearbox in a wind turbine changes what between rotor and generator?
A Wind direction
B Blade material
C Rotational speed
D Tower vibration only
Answer: C. Rotational speed. A gearbox raises slow rotor speed to suit the generator.
A direct-drive turbine omits which component?
A Generator
B Gearbox
C Power electronics
D Rotor blades
Answer: B. Gearbox. Direct-drive systems couple the rotor to a low-speed generator without a gearbox.
A horizontal-axis turbine rotates about an axis that is what?
A Parallel to wind flow
B Vertical to ground
C Perpendicular to tower
D Always stationary
Answer: A. Parallel to wind flow. Horizontal-axis rotors spin around an axis generally aligned with wind direction.
A vertical-axis turbine rotates about what orientation?
A Horizontal axis only
B Wind direction
C Vertical axis
D Blade chord
Answer: C. Vertical axis. Vertical-axis machines rotate around a vertical shaft.
Wind shear describes change in wind speed with what?
A Blade color
B Grid voltage
C Air humidity only
D Height above ground
Answer: D. Height above ground. Wind speed generally varies with height due to surface friction.
A turbine wake contains reduced wind speed and what?
A Higher solar radiation
B Zero temperature
C Higher pressure always
D Increased turbulence
Answer: D. Increased turbulence. A turbine wake has lower velocity and elevated turbulence.
Offshore wind farms are installed in what environment?
A Marine waters
B Desert only
C Urban rooftops only
D Underground mines
Answer: A. Marine waters. Offshore turbines are placed in coastal or marine waters.
Wind turbine capacity is usually rated in what?
A Electrical power
B Rotor mass
C Tower height
D Energy density only
Answer: A. Electrical power. Nameplate capacity is an electrical power rating, commonly MW.
A doubly-fed induction generator can support variable speed using what?
A Power converter
B Steam valve
C Hydraulic accumulator
D Solar tracker
Answer: A. Power converter. A partial-scale converter controls rotor currents and grid-side power.
Variable-speed operation can improve energy capture and what?
A Load control
B Tower height
C Blade count only
D Wind density
Answer: A. Load control. Variable speed helps maintain efficient aerodynamic operation and manage loads.
A nacelle houses drivetrain and what?
A Foundation piles
B Blade tips
C Generator
D Solar inverter only
Answer: C. Generator. The nacelle encloses the gearbox or direct-drive generator and related equipment.
Wind turbine foundations transfer loads into what?
A Cloud layer
B Grid transformer
C Ground or seabed
D Blade pitch system
Answer: C. Ground or seabed. Foundations carry turbine weight and dynamic loads into soil or seabed.
A pitch system can feather blades to reduce what?
A Grid frequency
B Aerodynamic loading
C Foundation depth
D Wind measurement error
Answer: B. Aerodynamic loading. Feathering turns blades to reduce captured power and structural loading.