X. Письменно ответьте на вопросы:

1. What is transformer used for?

2. What does a transformer consist of?

3. What is the function of the primary winding?

4. What is the function of the secondary winding?

5. What type of transformer is called a step-up transformer?

6. What type of transformer is used for high-frequency currents?

7. What type of transformer is called a step-down transformer?

8. What type of transformer is used for low-frequency currents?

9. What are common troubles in a transformer?

Вариант 4

I. Перепишите следующие предложения, определите в каждом из них видо- временную форму и залог глагола- сказуемого (см. Образец 1). Переведите предложения на русский язык.

1.At this stage the raw materials are loaded into this container.

2.This products have been designed by a special team.

3.Our engineers have improved this new method of work.

4.Advanced technologies are applied in most branches of engineering.

5.She is working in Rome at the moment.

2. Перепишите следующие предложения; подчеркните в каждом из них модальный глагол или его эквиваленты. Переведите предложения на русский язык.

1.He has to investigate a series of accidents that have occured in the locality during the last three month.

2.When are we to visit the laboratories of the Institute?

3.The engineer must know all the properties of this material.

4.This idea may be realized later.

5.He was able to do this work himself.

III. Перепишите следующие предложения; подчеркните Participle I и Participle II и установите функции каждого из них, т. е. укажите, является ли оно определением, обстоятельством или частью глагола- сказуемого. Переведите предложения на русский язык. (см. образец 2).

1.He has been writing the article since 10 o’clock.

2.While looking through the documents, he found several errors in them.

3.The company has been concentrating on the research and development of new products.

4.Heated to a certain temperature, this alloy increases in volume.

5.Having made many experiments proved that electricity had an atomic character.

IV. Перепишите следующие предложения и переведите их на русский язык, обращая внимание на функцию инфинитива.

1.To get the necessary books you have to go to the library.

2.He has the chance to study well.

3.Your aim in the meeting is to reach a decision about the future of the factory.

4.The distance to be covered was equal to ten miles.

5.It is impossible for us to accept these terms.

V. Перепишите следующие предложения и переведите их на русский язык, обращая внимание на герундий и его функцию.

1.A constant speed of the device is maintained by supplying it with energy.

2.Did you have any difficulty in solving this problem?

3.Steam is an important factor in producing usable energy because of the power being created by its expansion.

VI. Перепишите следующие предложения и переведите их на русский язык, обращая внимание на разные значения глаголов to be, to have, to do.

1. Coffee is usually imported from Brazil.

2. She is working in Moscow at that moment.

3. The pure scientist is to work in the area of applied science and research.

4. In Britain equal pay for women did not obtain legal sanction until the 1970s.

5. These basic problems are common to all societies.

VII. Перепишите следующие предложения и переведите их на русский язык, обращая внимание на разные значения слов it, that, one (см. образец 3).

1.The problem that discussed yesterday is very important.

2.One must choose only one of those variants.

3.It took her a week to prepare a balance sheet.

4.The new office is more comfortable than the previous one.

VIII. Перепишите следующие предложения и переведите их на русский язык, обращая внимание на бессоюзное подчинение.

1.The machines the farm got last year can be used both for harvesting and cultivation of vegetables.

2.We know a wholesale distributor is a company which sells goods in large quantities.

3.The irrigation work which our brigade had to do will help the farmers grow vegetables.

4.Everybody knows agriculture is connected with human life.

IX.Переведите текст и отработайте его чтение.

В тексте найдите:

1. предложения со сравнительной конструкцией the … the…;

2. глаголы в страдательном залоге;

3. неопределенные местоимения;

4. причастие I.

Inductance and Mutual Inductance

Any conductor has some definite value of inductance. The induc­tance of a conductor shows how well it can provide induced voltage.

Elements of a circuit with a definite value of inductance are coils of wire called inductors. The inductance of a coil depends upon its size and material. The greater the number of turns of a coil, the higher is its inductance. An iron core also increases the value of inductance. Coils of this type are used for low-frequency currents while coils with an air core are used for high-frequency currents.

Two coifs A and В are brought close together and a source of vary­ing current is applied to coil A. If a measuring device is connected across the terminals of coil В it will be found that a voltage is induced in this coil though the two coils do not touch. The secondary voltage, that is the voltage in coil B, is called induced voltage and energy from one coil to the other transfers by induction. The coil across which the

current is applied is called the pri­mary; that in which voltage is in­duced is called the secondary. The primary and the secondary coils have mutual inductance. Mutual induc­tance is measured in the same units as inductance, that is in henries.

Thus, when a rate of change of one ampere per second in the primary coil will produce one volt in the sec­ondary coil, the two coils have one henry of mutual inductance.

It should be taken into consideration that induction by a varying cur­rent results from the change in current not in the current value. The faster the current changes, the higher the induced voltage.