The nature of electricity.

Input

The only way to charge a body negatively is to add electrons to it, and the only way to charge it positively is to take electrons away from leaving an excess of positive electricity.

The ancient Greeks knew that when a piece of amber is rubbed with wool or fur it achieves the power of attracting light objects. Later оn phenomenon was studied, and, the word electric, after the Greek word “electron”, meaning amber was used. Many scientists investigated electric phenomena, and during the nineteenth century many discoveries about the nature of electricity, and of magnetism, which is closely related to electricity, were made. It was found that if a sealing-wax rod is rubbed with woolen cloth, and a rod of glass is rubbed with a silken cloth, an electric spark will pass between the sealing-wax rod and the glass rod when they brought near one another. Moreover, it was found that a force of attraction operates between them. An electrified sealing wax is repel let however, by a wax rod, and also an electrified glass rod is repelled, by similar glass rod.

The ideas were developed that there are two kinds of electricity, which were called resinous electricity, and that apposite kinds of electricity attract one another, whereas similar kinds repel one another. Although these simple electric and magnetic phenomena have been known since ancient times, most of the basic quantitative laws of electricity and magnetism were discovered between 1784, when Charles Coulomb investigated the forces between charged objects, and 1831, when M. Faraday discovered magnetic induction. Prior to this 50-year period of discovery, the only practical electric invention was the lightning rod of Benjamin Franklin (1752).

After this period, the practical utilization electricity increased rapidly with the development of the telegraph (1844), the telephone (1877), incandescent lighting (1880) and electric motors (1887). Uses of electricity have continued to expand to this day, with the current revolution in microelectronics giving us ever-increasing control over the machines.

The study of electricity may be divided into three classes or branches: magnetism, electrostatics, and electrodynamics. Magnetism is the property of the molecules of iron and certain other substances through which they store energy in a field of force because of the arranged movement of the electrons in their atoms. Electrostatics is the study of electricity at rest, or static electricity. Examples of this type of electricity are charges on condenser plates. Rubbing glass with silk produces static electricity. Electrodynamics is the study of electricity in motion, or dynamic electricity. The electricity that flows through wires for light and power purposes is a good example of latter type of electricity.

Step 3

Say what physical phenomenon the text is concerned with.

Step 4

Find the part of the text dealing with the fundamental forces of nature.

Discuss the information with your fellow students.

Step 5

Answer the following questions embracing the contents of the text.

1. What is the way to charge a body negatively or positively?

2. What capacity did amber and glass acquire when rubbed with silk or fur? .

3. What is magnetism?

4. When were the basic quantitative laws of electricity and magnetism discovered?

5. When did C, Coulomb investigate the forces between charged objects?

6. When did M. Faraday discover magnetic induction?

7. What was invented by B. Franklin?

Step 6.

Make up a short dialogue on the following situation;

1. A few students make an experiment with different materials to receive electricity.

2. Ask your fellow-student- about history of electricity and magnetism.