好吧。我们来谈谈验电器和电荷转移的方法。好吧。首先，我们知道外面有电荷但我们想要测量它。那我们要怎么做呢?我们要用一个叫验电器的东西。
验电器是一块金属，由一个把手、一根长电线和两片非常非常薄的金箔组成。好吧?所以这些都是连接的，它们都是导线这就意味着电荷可以自由地通过它们。好吧。这是怎么做到的呢?假设我把一根玻璃棒靠近验电器的把手，这个人被通电了。对吧?接下来会发生的是这个正电荷，它很喜欢这个负电荷。记住，积极的一面会吸引消极的一面。现在这些积极因素无处可去。 So they're just kind of stuck. But the negative charges inside the conductor can all conspire to jump up to the knob. So if the negatives come up out of the leaves into the knob, then that leaves positives down here. So both of the leaves are positively charged. But just like pit balls, that means they're going to repel each other. So these guys are going to move apart. And that's how we're going to measure it. We're just going to look at the leaves and if they move apart, means we got some charge. Alright?
那么负电荷呢?它会做同样的事情。看看会发生什么。消极的对吧?现在，负电荷不喜欢其他负电荷所以旋钮上的负电荷不是向上跑而是向下跑到叶片上。旋钮上的是正数，叶上的是负号。同样，它们会分开。所以使用不带电的验电器，我们可以测量电荷的存在，但是我们不能区分正电和负电。所以记住不带电的验电器很重要它可以告诉你这里有电荷但它不能告诉你正电和负电。好吧。 So how can we do that? Well, let's see.
如果我们给验电器充电呢?那么现在，如果我从一个带正电荷的验电器开始呢?这意味着这些叶子之间已经有一点距离了。现在我要拿一个带正电的玻璃棒靠近它。再次强调，它会吸引电子。它会吸引负电荷。所以我得到了负的负的。这又会留下什么呢?它留下了更多的积极因素。这就意味着这两个向量会移动得更远。 Okay. So that's the same thing that happened before. The uncharged electroscope. So what gives, what does that buy us? Well, what if I bring negative charge close?
负电荷会把负电荷吓到叶子里而把正电荷留在旋钮里。注意现在发生了什么。现在叶子的电荷减少了。这意味着它们会被引力吸引到一起。所以它们靠得更近。现在，有了带电的验电器，我就能分辨出，靠近把手的棒子，和验电器的电荷是一样的还是相反的。这很好。它能让整个系统运转起来。一旦我们选择了，玻璃棒是带正电的，然后我们就可以拿着它们，拿着任何带电的东西，看看会发生什么。我们可以知道它是带正电还是带负电。
好吧。首先，我们要怎么给这个验电器充电呢?有两种主要的方法可以让一开始不带电的物体带电。第一个是传导，传导是指把一个已经带电的物体接触到一个不带电的物体。现在，当我把它靠近的时候，这些正电荷会把所有的正电荷推到另一边把负电荷推到那边。这叫做极化。我已经把这个材料极化了。好吧。所以现在当我让它们接触时，一些负号会跳过去。然后我把它们分开，看看剩下的是什么，它带正电。 So that's charging by conduction. Charging by conduction is very very very simple. It gives you the same charge that you started off with and it involves direct contact between the two things. Alright.
另一种方式是感应充电。现在，这有点不同。再一次，我要把这个杆子靠近但不接触，我要充电的东西。好吧。再一次，负号聚集在这里正号聚集在这里。但是现在，我要做的是，我要拿另一个物体，我要把它靠近，这个东西一开始是不带电的。我要把它靠近我要收费的这个家伙。现在，这意味着它接近这些积极因素，这些积极因素比消极因素更强。所以这里有一堆负号。好吧。 And then a bunch of positives up here. Now, when I touch these guys together, what's going to happen is the negatives are going to jump across because they want to be closer to this positive charge. So that gives me a net, negative charge here and a net positive charge here. So when I charge this object by induction, I get the opposite charge on the thing that I charged than I had on the thing that I used to charge. Induction is an indirect way of charging. Notice that at no point did I touch the initial thing that I had charged to anything. So that means that I don't have to recharge it later. I can use it again and again and again. Alright, great. So induction, indirect. Alright?
这就是验电器和电荷转移。
