But often, you’ll be inducing emf in a coil of wire – like what Faraday was doing in his experiment – so it helps to know how a change in the magnetic flux will induce emf in a coil.

但通常，你会在一个线圈中感应电动势——就像法拉第在他实验中所做那样——所以了解磁场变化如何在线圈中感应电动势是有帮助。

Well, no traces of EMF, that's for sure.

没有电动势反应 这点很确定。

Now, we can calculate the strength of the emf in a generator using some of the principles we talked about last time.

现在，我可以使用我讨论一些计算生成器中电动势强度。

And when that field changes? That’s what induces an emf.

当这个磁场发生变化时？这就是诱导电动势因。

So, when you measure the actual voltage between the terminals of the battery, you get a value that’s less than our ideal emf potential.

因此，当您测量电池端子之间实际电压时， 您会得到一个低于我想电动势值。

It says that a changing magnetic field will induce an emf in a loop of wire.

它说不断变化磁场会 在线圈中感应出电动势。

Scientists say that the battery is a source of electromotive force, because it gets charge to move – but it's not really providing a force, but rather a difference in electrical potential.

科学家说，电池是电动势源，因为它使电荷移动——但它实际并不提供力，而是提供电位差。

And emf, you’ll recall, stands for electromotive force, which is what causes electrons to move and form a current.

而电动势，你可能还记得，它是电磁力一种表现，正是它使得电子移动并形成电流。

In maths terms, we'd say that the emf is equal to the negative of the change in flux, over the change in time.

用数学术语说，我会说电动势等于通量变化负数，随着时间变化。

These days, we call this idea Faraday’s Law of Induction: It says that a changing magnetic field will induce an emf in a loop of wire.

如今，我将这个概念称为法拉第感应定律：它说明变化磁场会在导线回路中感应出电动势。

Today, you learned about magnetic flux, and how a change in magnetic flux can induce an emf in a loop or coil of wire.

今天，您了解了磁通量，以及磁通量变化如何在线圈或线圈中产生电动势。

Scientists say that the battery is a source of electromotive force, because it gets charge to move – but it’s not really providing a force, but rather a difference in electrical potential.

科学家说， 电池是电动势源， 因为它需要充电才能移动——但它并不是真正提供力， 而是提供电势差。

So the magnetic flux through the second coil changes, which induces an emf.

因此，通过第二个线圈磁通量会 发生变化，从而产生电动势。

In maths terms, we’d say that the emf is equal to the negative of the change in flux, over the change in time.

用数学语言说，我可以说电动势等于磁通量变化负值除以时间变化。

So now Faraday knew that when a magnetic field changed over time, it induced an emf in a loop of wire.

所以现在法拉第知道，当磁场随时间变化时，它会在线圈中感应出一个电动势。

So! Faraday’s law of induction lets us calculate how much emf – and therefore, how much current – will be induced in a loop of wire by a change in magnetic flux.

所以！法拉第感应定律让我能够计算出磁场变化会在导线环路中感应出多少电动势——也就是多少电流。

And to calculate an induced emf, you just take the change in current over time and multiply it by negative L.

要计算感应电动势，只需将电流随时间变化乘以负。

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·法拉第向我展示了变化磁场如何产生电动势或电动势，从而产生电流。

So an emf is induced in the second coil.

因此在第二个线圈中感应出一个电动势。

But when it comes to inducing emf, what really matters is how the flux is changing over time.

但是当涉及到感应电动势时，真正 重要是通量如何随时间变化。