I. Прочитайте текст, переведите его письменно.
One of the most useful properties of electricity is its ability to produce heat. Electricity produces heat in a conductor as it overcomes the conductor's resistance to the flow of electrons through it, just as mechanical energy produces heat in overcoming friction. The heat-producing effect of electricity is used in electric ranges, toasters, soldering irons, and many other devices. In incandescent light bulbs, the effect is used to make a filament glow brightly.
Another very useful property of electricity is that it can be a source of magnetism; electrons flowing through a wire create a magnetic field around the wire. This effect is the basis for the operation of electromagnets, which make possible electric motors, telephones, loudspeakers, and many other devices.
Electricity has several other useful properties. It can be made to jump a narrow gap separating two conductors, creating a spark. An important application of such sparks is in igniting the fuel in the cylinders of gasoline engines. Electricity can also produce chemical changes.
In a gas or vacuum, electrons can be accelerated to high speed and directed in specific directions. Electrons used in this way make possible many kinds of devices, including television picture tubes, fluorescent lights, and X-ray tubes. In certain semiconductor devices, such as transistors, the movement of electrons can be readily controlled by electrical means. Such devices are used in computers, radios, tape recorders, and many other products.
Electricity is most easily explained by the electron theory, developed in the early 20th century. The electron theory, in turn, depends on the atomic theory of matter.
The center, or nucleus, of an atom contains one or more particles called protons. A proton has a type of electric charge that is said to be positive. Circling the nucleus are one or more electrons, which are much smaller than the proton. An electron has a type of charge that is said to be negative.
An electrically neutral atom has one electron for each proton. In such an atom, the positive and negative charges exactly balance. An atom may lose or gain one or more electrons, leaving it with a net positive or negative charge. A charged atom is called an ion.
II.Составьте свой вокабуляр из слов, встретившихся при переводе текста.
III. Ответьте письменно на вопросы по тексту. Вопросы перепишите.
1) Which useful properties of electricity do you know?
2) What does the electron theory depend on?
3) What is a proton?
IV. Найдите в тексте эквиваленты следующих слов и словосочетаний:
Light bulbs, the flow of electrons, the conductor's resistance, soldering irons, device, to jump a narrow gap separating two conductors, semiconductor devices, to depend on, X-ray tubes, an ion, a type of charge, an atom may lose or gain one or more electrons.
V. Поставьте глагол-сказуемое в нужной форме (Present, Past, Future Simple)
1. She (not/ to teach) English at school.
2. You (to meet) him yesterday?
3. The firm (to buy) new computers next month.
4. The Dean (to ask) many questions at the lecture last week.
5. Where you (to go) next summer?
6. They (to use) new scientific data for their last experiment.
7. When the concert (to be over) all the people (to leave) the hall.
8. Every year students (to take part) in scientific research.
9. The first computer (to appear) in the 1960-s.
10. If the weather (to be) fine, we (to go) to the village.
VI. Употребите правильную форму глагола в условных предложениях:
1. I (interpret) … for you at the conference tomorrow if I (be) … not already scheduled to work at the UN. I have a friend who (do) … it for you, if she (be, not) … busy. 2. If I (have) enough money, I (backpack) around Europe. But, unfortunately, I am broke. 3. If I (have) enough money in my twenties, I (backpack) around Europe. But, unfortunately, I was broke. 4. If the price of this tour to GB (come) down, more people will buy it.
VII. Переведите на английский язык, учитывая три типа условных предложений:
1. Я помогу вам, если приду рано. 2. Если бы он был осторожнее, он бы не попал в дорожное происшествие. 3. Я дам вам мой номер телефона на тот случай, если вы захотите мне позвонить. 4. Если бы она принялась учить английский еще в детстве, она бы знала его сейчас очень хорошо. 5. Если бы он не ел так много, он бы не умер так рано.
VIII. Из нескольких вариантов (1, 2, 3, 4) выберите единственно правильный.
If I had known you had a mobile phone I... you.
1. would contact 2. had contacted
3. contacted 4. would have contacted