График сдачи переводов научно-технической литературы

Linguae Centrum

Письменный перевод оригинального текста по специальности

«Электрические и электронные аппараты»

64 тыс. печ. зн.

Студент: Шумеев И.М.

Преподаватель: Ворохобин А.А..

Москва 2012

Фамилия, Имя: Шумеев И.М.

Специальность: Электрические и электронные аппараты

График сдачи переводов научно-технической литературы

ИТОГО сдано: 64200 печатных знаков.

Преподаватель: Ворохобин А.А.

Содержание

James S. Walker. Physics. Chapter 19. Electric Charges, forces and fields 3

Джеймс Уолкер. Физика. Глава 19. Электрические заряды, силы и поля 14

J. Zumerchik-Macmillan. Encyclopedia of Energy. Vol.1. “Electric motor systems”.. 26

Дж.Зумерчик-Макмиллан. Энциклопедия энергии. Том 1. Электродвигатели 30

J. Zumerchik-Macmillan. Encyclopedia of Energy. Vol.1. 35

“ELECTRIC POWER, SYSTEM PROTECTION, CONTROL, AND MONITORING OF”.. 35

Дж.Зумерчик-Макмиллан. Энциклопедия энергии. Том 1. ЭЛЕКТРОЭНЕРГЕТИКА, СИСТЕМЫ ЗАЩИТЫ КОНТРОЛЯ И МОНИТОРИНГА... 43

NIKOLA TESLA. TRANSMISSION OF ELECTRICAL ENERGY WITHOUT WIRES.. 53

Никола Тесла. ПЕРЕДАЧА ЭЛЕКТРИЧЕСКОЙ ЭНЕРГИИ БЕЗ ПРОВОДОВ... 60

NIKOLA TESLA. The Adantean Power System.... 69

Никола Тесла. Энергосистема Adantean. 71

James S. Walker. Physics.
Chapter 19. Electric Charges, forces and fields

Introduction

We are all made up of electric charges. Every atom in every human body contains both positive and negative charges held together by an attractive force that is similar to gravity—only vastly stronger. Our atoms are bound together by electric forces to form molecules; these molecules, in turn, interact with one another to produce solid bones and liquid blood. In a very real sense, we are walking, taking manifestations of electricity.

In this chapter, we discuss the basic properties of electric charge. Among these are that electric charge comes in discrete units (quantization) and that the total amount of charge in the universe remains constant (conservation), In addition, we present the force law that describes the interactions between electric charges. Finally, we introduce the idea of an electric field, and show how it is related to the distribution of charge.

Electric Charge

The effects of electric charge have been known since at least (600 B.C. About that time, the Greeks noticed that amber—a solid, translucent material formed from the fossilized resin of extinct coniferous trees—has a peculiar property, If a piece of amber is rubbed with animal fur, it attracts small, lightweight objects. This phe­nomenon is illustrated in Figure 19-1.

For some time, it was thought that amber was unique in its ability to become "charged." Much later, it was discovered that other materials can behave in this way as well. For example, if glass is rubbed with a piece of silk, it too can attract small objects. In this respect, glass and amber seem to be the same. It turns out, however, that these two materials have different types of charge.

To see this, imagine suspending a small, charged rod of amber from a thread, as in Figure 19-2. If a second piece of charged amber is brought near the rod, as shown in Figure 19-2 {a), the rod rotates away, indicating a repulsive force be­tween the two pieces of amber. Thus, "like" charges repel. On the other hand, if a piece of charged glass is brought near the amber rod, the amber rotates toward the glass, indicating an attractive force. This is illustrated in Figure 19-2 (b). Clearly, then, the different charges on the glass and amber attract one another. We refer to different charges as being the "opposite" of one another, as in the familiar expres­sion "opposites attract."

We know today that the two types of charge found on amber and glass are, in fact, the only types that exist, and we still use the purely arbitrary names-positive {+) charge and negative (—) charge—proposed by Benjamin Franklin (1706-1790) in 1747. In accordance with Franklin's original suggestion, the charge of amber is negative, and the charge of glass is positive (the opposite of negative), Calling the different charges + and — is actually quite useful mathematically; for example, an object that contains an equal amount of positive and negative charge has zero net charge. Objects with zero net charge are said to be electrically neutral.

A familiar example of an electrically neutral object is the atom. Atoms have a small, dense nucleus with a positive charge surrounded by a cloud of negatively charged electrons (from the Greek word for amber, elektnin). A pictorial represen­tation of an atom is shown in Figure 19-J.

All electrons have exactly the same electric charge. This charge is very small and is defined to have a magnitude, e, given by the following:

Magnitude of an Electron's Charge, e

e = 1.60 * 10^-19 C 19-1

SI unit: coulomb, C

In this expression, C is a unit of charge referred to as the coulomb, named for the French physicist Charles-Augustin de Coulomb (1736-1806). (The precise definition of the coulomb is in terms of electric current, which we shall discuss in Chapter 21.) Clearly, the charge on an electron, which is negative, is -e. This is one of the defining, or intrinsic, properties of the electron. Another intrinsic property of the electron is its mass, Me-

Me = 9.11*10^-31 kg 19-2

In contrast, the charge on a proton—one of the main constituents of nuclei—is exactly +e. Therefore, the net charge on atoms, which have equal numbers of elec­trons and protons, is precisely zero. The mass of the proton is

Mp = 1.673 * 10^-27 kg 19-3

Note that this is about 2000 times larger than the mass of the electron. The other main constituent of the nucleus is the neutron, which, as its name implies, has zero charge. Its mass is slightly larger than that of the proton:

Mn = 1.675 x 10^-27 kg 19-4

Since the magnitude of the charge per electron is 1.60 * 10^-19 C/electron, it fol­lows that the number of electrons in 1 C of charge is enormous: 1C = 6.25 X 10^18 electrons

As we shall see when we consider the force between charges, a coulomb is a sig­nificant amount of charge; even a powerful lightning bolt delivers only 20 to 30 C. A more common unit of charge is the microcoulomb, µC, where 1 µC = 10^-6 C. Still, the amount of charge contained in everyday objects is very large, even in units of the coulomb.

Charge Separation

How is it that rubbing a piece of amber with fur gives the amber a charge? Originally, it was thought that the friction of rubbing erected the observed charge. We now know, however, that rubbing the fur across the amber simply results in a transfer of charge from the fur to the amber—with the total amount of charge remaining unchanged. This is indicated in figure W-4. Before charging, the fur and the amber are both neutral. During the rubbing process some electrons arе transferred from the fur to the amber, giving the amber a net negative charge; and leaving the fur with a net positive charge. At no time during this process is charge ever created or destroyed. This, in fact, is an example of one of the fundamental conservation laws of physics:

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