98 Electricity and Magnetism-Mid

Electricity and Magnetism Written by David Dreier

《电与磁》大卫·德雷尔著

Introduction Have you ever watched flashes of lightning during a big storm at night? 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 make and use their own electricity. Whenever you turn on a light you are using electricity, Computers and televisions can't work without electricity, either. Electricity has become such an important part of our lives that it is hard to imagine the world without it. Magnetism is also a familiar part of our world. Perhaps you have played with magnets or have magnets on your refrigerator door. Did you know that magnetism is closely related to electricity? This book will teach you about electricity and magnetism, and how they are related.

你曾经在暴风雨的夜晚看到过闪电吗? 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自己制造和使用电。 不管你什么时候开灯，你都是在用电，电脑和电视也不能没有电工作。 电已经成为我们生活中如此重要的一部分，很难想象没有它的世界。 磁性也是我们世界中熟悉的一部分。 也许你玩过磁铁，或者你的冰箱门上有磁铁。 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. It comes from very tiny particles called atoms. Atoms are the smallest bits of elements, the basic substances that everything is made of. Inside each atom are even smaller particles called protons, neutrons, and electrons. Protons and neutrons make up an atom's center, called the nucleus. Electrons whirl around the nucleus. Protons and electrons have a feature called electrical charge. This feature is the source of electricity. Protons have a charge that scientists call positive. Electrons have an opposite charge called negative. Neutrons are neutral, meaning they have no charge.

电是什么?你刚学过电学? 可以自然产生，也可以人为产生。 但是电是什么?它是能量的一种形式。 它来自于被称为原子的非常微小的粒子。 原子是最小的元素，是构成万物的基本物质。 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。 电子绕着原子核旋转。 质子和电子有一个特征叫做电荷。 这个特征就是电的来源。 质子带有一种科学家称之为正电荷的电荷。 电子有一个相反的电荷，叫做负电荷。 中子是中性的，也就是说它们不带电荷。

Charges of the same kind repel each other. So two protons repel each other, and so do two electrons. Charges that are opposite attract each other. So a proton and an electron are attracted to each other. However, electrons do not get pulled into the nucleus, even though they are attracted by the protons. That is because they are moving so fast. The number of positive protons and negative electrons in an atom is usually equal. Because the charges are equal in number, they cancel each other out. The atom is neutral, meaning it has no charge.

同种电荷相互排斥。 两个质子相互排斥，两个电子也相互排斥。 相反的电荷相互吸引。 一个质子和一个电子相互吸引。 然而，即使电子被质子吸引，它们也不会被拉进原子核。 那是因为它们移动得太快了。 原子中正电子和负电子的数量通常是相等的。 因为电荷数相等，它们就互相抵消了。 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 is no longer neutral. It now has a negative charge. If an atom loses electrons, the protons outnumber the electrons. The atom now 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 that has more protons than electrons is a positive ion.

原子可以通过接触其他原子而获得或失去电子。 如果原子得到电子，它就不再是中性的了。 它现在带一个负电荷。 如果一个原子失去电子，质子的数量就会超过电子。 原子现在带一个正电荷。 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。

The Two Kinds of Electricity There are two kinds of electricity. They are static electricity and electric currents. Both kinds of electricity involve the production and movement of charges. But they act 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 separated charges becomes strong enough, the particles quickly stream back together. Lightning is caused by static electricity. In storm clouds, strong winds cause a buildup of electrons and positive ions. The charges collect in different parts of the cloud. When the collections of charges get big enough, they rapidly flow back together. This heats the surrounding air and causes a lightning flash. Most lightning occurs inside clouds or between clouds. WOWSER! 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! The burst of energy creates a bright flash of light. At the same time, the lightning bolt causes the air to expand violently. That is what produces thunder.

两种电有两种电。 它们是静电和电流。 两种电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。 当分离电荷之间的吸引力变得足够强时，粒子就会迅速流回一起。 闪电是由静电引起的。 在风暴云中，强风会引起电子和正离子的积聚。 电荷在云的不同部分聚集。 当聚集的电荷足够大时，它们就会迅速地流回一起。 这会加热周围的空气并引起闪电。 大多数闪电发生在云内或云间。 老古板!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!能量的爆发产生了明亮的闪光。 同时，闪电使空气剧烈膨胀。 这就是产生雷声的原因。