Herschel, Peter Barlow and others, but did not receive a final explanation until after the discovery of electromagnetic induction by Faraday in 1831.
He not only collected the facts concerning electromagnetic induction so industriously that nothing of importance remained for future discovery, and embraced them all in one law of exquisite simplicity, but he introduced his famous conception of lines of force which changed entirely the mode of regarding electrical phenomena.
Neumann in 1845 did for electromagnetic induction what Ampere did for electrodynamics, basing his researches upon the experimental laws of Lenz.
The theory part covers the basics of electromagnetic induction.
A generator is the device that collects the wind energy from the shaft and uses electromagnetic induction to produce voltage; a usable type of power.