When they hear the name Ben Franklin, many folks think of the Declaration of Independence, the Continental Congress and things like that. Not as many people remember that Franklin was an inventor . . . and a good one, too! He also did some pioneering work in physics.

　　Think Fur

　　Sure, sure, you say. You think I’m about to tell that old story about flying a kite in a thunderstorm. I can see you reaching for the knob on your radio. But wait!

　　Forget about the kite and think fur instead. Franklin took some fur and rubbed it across a rubber rod. He had suspended the rod by a thin string. Then he tried it with a glass rod. Then he used silk instead of fur. What was he up to?

　　He was experimenting with electric charge. The glass rod rubbed with silk repelled another glass rod rubbed with silk. The rubber rod rubbed with fur attracted the glass rod. That’s why he was hanging them by strings; when they are free to move, you can easily see the attraction and repulsion at work.

　　Electrical Charge

　　Nowadays we know that what Franklin was doing was finding different ways to change the net electrical charge on various substances by knocking around electrons. Electrons are tiny, negatively charged particles. Since objects start out with equal amounts positive and negative charge, rubbing electrons off a glass rod with silk will give the glass net positive charge.

　　Franklin didn’t know about electrons, but using only very simple materials, he had shown that opposite charges attract and like charges repel! He even coined the terms “positive” and “negative.”

　　Not bad for someone who was helping found new countries in his spare time.

　　富兰克林与他的毛皮实验

　　当人们听到本杰明-富兰克林这个名字时，独立宣言，大陆会议等事件立即浮现在眼前。而作为发明家的富兰克林却不大为人所知。其实他是一名优秀的发明家，并曾在物理学方面做过一些开创性的工作。

　　思考皮毛

　　你连忙说“是是是”，你认为我还是要给你讲老掉牙的电闪雷鸣放风筝的故事。我可以看到你的手伸向电台准备换频道。请等等！

　　忘掉风筝的事情吧，思考一下皮毛。富兰克林拿一些皮毛与一根橡胶棒进行摩擦。他用一根细绳将橡胶棒悬空挂起。然后他用一根玻璃棒又试了一下。然后他用丝巾代替了皮毛。他到底想干什么呢？

　　他在做电荷实验。用丝巾摩擦过的玻璃棒相互排斥，但是皮毛摩擦过的橡胶棒却与玻璃棒相互吸引。这是他将棒子用细绳悬空而挂的原因。当它们可以自由运动时，你很容易就可以看到它们相吸和相斥的场景。

　　电荷

　　如今我们懂得富兰克林实验的目的是通过摩擦电子，通过各种不同的途径在不同的物质上转移电子以改变净电荷。电子是微小的带负电荷的粒子。由于媒介起初带有相等数量的正负电子，玻璃棒与丝巾的摩擦会使得玻璃棒只带有净正电子。

　　富兰克林并不知道电子，但是仅仅使用非常简单的材料，他证明了异性电荷相互吸引，同性电荷相互排斥！他甚至创造了专有名词“正”和“负”。

　　在建立新国家的同时，业余时间做点新鲜事也是个不错的选择。