Electromagnetic induction

Induced voltage (V) is proportional to the rate of change of flux (Flux F = B.A).

Flux can be cut with a blade, or changed by rotating a loop in a magnetic field, or changing the field strength in a loop.

 

Helicopter blades rotate in a magnetic field. The voltage induced between the tip of a blade and the axle is proportional to the length of the blade, the speed of rotation, and the strength of the vertical component of the Earth's magnetic field.

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