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phenomenon— феномен
static — статический
determine — определять,
circuit— цепь, схема
to melt— плавить
a.c.-переменный ток
d.c.- постоянный ток
Exercise 1.1. Answer the questions:
1. What is electric current?
2. Who was the unit of current named after?
3. Who determined the difference between the current and the static charges?
4. What did Ampere suppose?
5. What can you say about an electron?
6. What charges do you know?
7. When does a wire carry an electric current?
8. Do liquids conduct current?
9. What can you say about the electrolytes?
10. What do you call d.c?
11. What is the advantage of a.c?
12. Where is a.c. used?
13. Who first applied a.c?
14. What does the current consist of?
Exercise 1.2. Find the following equivalents in the text:
1. источник постоянного тока
2. статические заряды
3. направление тока
4. крошечная частица
5. расплавленные металлы
6. постоянный (переменный) ток
7. положительно (отрицательно) заряженный
8. низкое (высокое) напряжение
9. напряжение повышается (понижается)
10. передача на большие расстояния
11. различные устройства
12. применять переменный ток на практике
Exercise 1.3. Find the wrong statements and correct them:
1. Electrons flow from the positively charged terminal of the battery to the negatively charged terminal.
2. Ampere supposed the current to flow from the negative pole to the positive one.
3. Static electricity is used for practical purposes.
4. Static electricity is not very high in voltage and it is easy to control it.
5. Volta took great interest in atmospheric electricity and began to carry on experiments.
6. The direct current is known to flow first in one direction and then in the opposite one.
7. The direct current used for power and lightning purposes is assumed to go through 50 cycles a second.
Exercise 1.4. Translate into English:
1. Вольт впервые открыл источник постоянного тока.
2. Единица тока была названа в честь Ампера.
3. Ампер определил разницу между током и статическими зарядами.
4. Ток идет по проводам вокруг цепи от положительного полюса и возвращается к отрицательному.
5. Ток течет в противоположном направлении.
6. Ток — это движение электронов.
7. Крошечные заряды движутся по проводам.
8. Ток может проходить через жидкости и газы.
9. Расплавленные металлы проводят ток.
10. Когда ток проходит через электролиты, они изменяются.
11. Постоянный ток — это однонаправленное движение электронов.
12. Переменный ток — это движение электронов.
Exercise 1.5. Translate the 2nd and the 3rd paragraphes.
Вариант 6
Read the text:
ELECTRIC CIRCUIT
1.The electric circuit is the subject to be dealt with in the present article. But what does the above term really mean? We know the circuit to be a complete path, which carries the current from the source of supply to the load and then carries it again from the load back to the source. The purpose of the electrical source is to produce the necessary electromotive force required for the flow of current through the circuit.
2.The path along which the electrons travel must be complete otherwise no electric power can be supplied from the source to the load. Thus we close the circuit when we switch on our electric lamp. If the circuit is broken or, as we generally say, "opened" any-where, the current is known to stop everywhere. Hence, we break the circuit when we switch off our electrical devices. Generally speaking, the current may pass through solid conductors, liquids, gases, vacuum, or any combination of these. It may flow in turn over transmission lines from the power-stations through transformers, cables and switches, through lamps, heaters, motors and so on. There are various kinds of electric circuits such as open circuits, closed circuits, series circuits, parallel circuits and short circuits.
3. To understand the difference between the following circuit connections is not difficult at all. When electrical devices are connected so that the current flows from one device to another, they are said to be connected in series. Under such conditions the current flow is the same in all parts of the circuit, as there is only a single path along which it may flow. The electrical bell circuit is considered to be a typical example of a series circuit. The parallel circuit provides two or more paths for the passage of current. The circuit is divided in such a way that part of the current flows through one path, and part through another. The lamps in your room and your house are generally connected in parallel.
4. Now we shall turn our attention to the short circuit some-times called "the short". The short circuit is produced when the current is allowed to return to the source of supply without control and without doing the work that we want it to do. The short circuit often results from cable fault or wire fault. Under certain conditions, the short may cause fire because the current flows where it was no supposed to flow. If the current flow is too great, a fuse is to be used as a safety device to stop the current flow. The fuse must be placed in every circuit where there is a danger of overloading the line. Then all the current to be sent will pass through the fuse. When a short circuit or an overload causes more current to flow than the carrying capacity of the wire, the wire becomes hot and sets fire to the insulation. If the flow of current is great than the carrying capacity of the fuse, the fuse melts and opens the circuit. A simple electric circuit is illustrated in Figure. In this figure a 4-cell battery has been used, the switch being in an open position. If the switch is in closed position, the current will flow around the circuit in the direction shown by the arrows.
Дата: 2019-11-01, просмотров: 417.