99 Electricity and Magnetism-High

Electricity and Magnetism Written by David Dreier

《电与磁》大卫·德雷尔著

Introduction Have you ever looked out a window at night and watched flashes of lightning split the night sky during a raging thunderstorm? You might be surprised to know that lightning is a natural form of electricity. In the last two hundred years, people have learned how to produce and harness electricity. Whenever you flip a switch to turn on a light, you are using electricity. Computers and televisions can't work without electricity. Electricity has become such an important part of our everyday lives that it is difficult to imagine the world without it. Magnetism is also a familiar part of our world. Perhaps you have played with magnets or use magnets on your refrigerator door. Did you know that magnetism is closely related to electricity? This book will teach you about electricity and magnetism, as well as how they are related.

你是否曾在夜晚透过窗户看到过雷雨肆虐时闪电划破夜空? 你可能会惊讶地发现闪电是电的一种自然形式。 在过去的200年里，人们已经学会了如何生产和利用电。 当你按下开关开灯时，你就是在用电。 电脑和电视没有电就不能工作。 电已经成为我们日常生活中如此重要的一部分，很难想象没有它的世界会是什么样子。 磁性也是我们世界中熟悉的一部分。 也许你玩过磁铁，或者在冰箱门上用过磁铁。 你知道磁与电密切相关吗? 这本书将教你关于电和磁，以及它们之间的关系。

What Is Electricity? You just learned that electricity can be produced naturally or by people. But what is electricity? It is a form of energy. Electrical energy comes from tiny, invisible particles called atoms. Atoms are the smallest bits of elements, the basic substances that make up all matter. Inside each atom are even smaller particles called protons, neutrons, and electrons. Protons and neutrons make up an atom's center, called the nucleus. Protons have a positive charge, while neutrons are neutral, meaning they have no charge. Electrons have a negative charge. Charges of the same kind— such as two positive charges— repel each other. Charges that are opposite— a positive and a negative charge— attract each other.

电是什么?你刚刚知道电可以自然产生，也可以由人产生。 但是电是什么?它是能量的一种形式。 电能来自于微小的、看不见的粒子——原子。 原子是最小的元素，是构成所有物质的基本物质。 在每个原子内部还有更小的粒子，叫做质子、中子和电子。 质子和中子组成原子的中心，称为原子核。 质子带正电荷，而中子是中性的，也就是说它们不带电荷。 电子带负电荷。 同种电荷，如两个正电荷，相互排斥。 相反的电荷——正电荷和负电荷——相互吸引。

Because electrons and protons are drawn to one another, you might wonder why electrons don't get pulled into the nucleus of an atom. They don't because electrons whirl around the nucleus very quickly. Their high speed keeps them from crashing into it. Normally, the number of positive protons and negative electrons in an atom is equal. Because the number of positive charges is equal to the number of negative charges, they cancel each other out. The atom is neutral, meaning it has no charge.

因为电子和质子相互吸引，你可能想知道为什么电子不被拉进原子核。 它们不会，因为电子绕原子核旋转非常快。 它们的高速使它们不会撞上它。 通常情况下，原子中正电子和负电子的数量是相等的。 因为正电荷的数量等于负电荷的数量，所以它们互相抵消了。 原子是中性的，也就是说它不带电荷。

Atoms can gain or lose electrons by contacting other atoms. If an atom gains electrons, it acquires a negative charge because the electrons outnumber the protons. If an atom loses electrons, the protons outnumber the electrons, so the atom has a positive charge. An atom that has a charge is called an ion. An atom that has more electrons than protons is a negative ion. An atom with more protons than electrons is a positive ion. It is important to remember that charges do not exist by themselves. A charge is always connected to a particle. Negative charges are carried by either electrons or negatively charged ions. Positive charges are carried by protons or positively charged ions.

原子可以通过接触其他原子而获得或失去电子。 如果一个原子获得了电子，它就获得了一个负电荷，因为电子的数量超过了质子。 如果一个原子失去电子，质子的数量就会超过电子，所以这个原子就带正电荷。 带电荷的原子叫做离子。 电子比质子多的原子是负离子。 质子比电子多的原子是正离子。 重要的是要记住电荷本身是不存在的。 电荷总是与粒子相连的。 负电荷由电子或带负电荷的离子携带。 正电荷由质子或带正电的离子携带。

The Two Kinds of Electricity There are two kinds of electricity: static electricity and electric currents. They both involve the production and movement of charges. But they behave in very different ways. Static Electricity Static electricity is caused by a buildup of negative charges in one place and positive charges in another. When the attraction between the positive and negative charges becomes strong enough, the particles quickly stream back together. Lightning is the most dramatic example of static electricity. In storm clouds, strong winds cause icy particles to collide violently. These collisions strip away many of the particles' outer electrons, leaving the cloud full of positive ions and free electrons. The positive ions move to the top of the cloud. The electrons, which have a negative charge, collect at the base of the cloud. When the collections of positive and negative charges get large enough, they rapidly flow back together. As they do, the energy of their motion heats the surrounding air and creates a lightning flash. A lightning bolt heats the air around it to about 30,000°C (54,000°F). That's five times as hot as the surface of the Sun!

两种电有两种电:静电和电流。 它们都涉及电荷的产生和移动。 但它们的行为方式非常不同。 静电是由于负电荷在一处积聚而正电荷在另一处积聚而产生的。 当正电荷和负电荷之间的吸引力变得足够强时，粒子就会迅速流回一起。 闪电是静电最引人注目的例子。 在风暴云中，强风导致冰粒子猛烈碰撞。 这些碰撞带走了许多粒子的外层电子，留下了充满正离子和自由电子的云团。 正离子移动到云的顶部。 带负电荷的电子聚集在云的底部。 当正电荷和负电荷聚集到足够大的时候，它们就会迅速地回到一起。 当它们这样做的时候，它们运动的能量会加热周围的空气并产生闪电。 闪电将周围的空气加热到约30,000°C(54,000°F)。 这是太阳表面温度的五倍!