If you remember, Faraday's Law of Induction says that a changing magnetic field will induce an electromotive force in a loop of wire.

如果你还记得的话，法拉第定律说变化的磁场会在线圈中感应出电动势。

First, in the early 1800s, Michael Faraday showed us how a changing magnetic field induces an electromotive force, or emf, resulting in an electric current.

首先，在 19 世纪初，迈克尔·法拉第向我们展示了变化的磁场如何产生电动势或电动势，从而产生电流。