Лекция: Задание 7. Прочитайте текст и переведите его письменно.
CONDUCTORS AND INSULATORS
All substances have some ability of conducting the electric current, however, they differ greatly in the ease with which the current can pass through them. Metals, for example, conduct electricity with ease while rubber does not allow it to flow freely. Thus, we have conductors and insulators.
What do the terms «conductors» and «insulators» mean? Substances through which electricity is easily transmitted are called conductors. Any material that strongly resists the electric current flow is known as an insulator.
Let us first turn our attention to conductance, that is the conductor's ability of passing electric charges. The four factors conductance depends on are: the size of the wire used, its length and temperature as well as the kind of material to be employed.
As mentioned above, there is a great difference in the conducting ability of various substances. For example, almost all metals are good electric current conductors. Nevertheless, copper carries the current more freely than iron; and silver, in its turn, is a better conductor than copper.
Generally speaking, copper is the most widely used conductor. That is why the electrically operated devices in your home are connected to the wall socket by copper wires. If we use a piece of string instead of a metal wire, we shall find that the current stops flowing.
A material like string which resists the flow of the electric current is called an insulator.
There are many kinds of insulation used to cover the wires. The kind used depends upon the purposes the wire or cord is meant for. The insulating materials we generally use to cover the wires are rubber, asbestos, glass, plastics and others.
Conducting materials are by no means the only materials to play an important part in electrical engineering. There must certainly be a conductor, that is a path, along which electricity is to travel and there must be insulators keeping it from leaking off the conductor.
Задание 8. Перепишите вопрос и ответьте на него письменно на английском языке, используя текст.
What is the use of insulators?
Задание 9. Составьте 5 вопросов разных типов к предложению из текста:
The electrically operated devices in your home are connected to the wall socket by copper wires.