Telephone communication.

Another important kind of wired communication is telephony. It is the transmission of speech over a considerable distance by means of electric current. Telephone set includes a transmitter, and an electric network in addition to receiver.

The transmitter or microphone consists of a diaphragm, carbon chamber with carbon granules and insulating spacer and conductor. The electric current passes through the diaphragm and carbon granules. When we speak we produce sound waves which make the diaphragm vibrate. The diaphragm in its turn pushes the carbon granules which makes more or fewer contacts and decreases or increases the resistance. Thus the waves of electric current vary depending on the sounds we produce and pass along the line and finally reach the receiver. The receiver consists of electromagnet coils, a steel magnet and a diaphragm. A variable current passing through the magnet's coil makes the diaphragm vibrate. The frequency of these oscillations is the same as that of the transmitter. Therefore the receiver reproduces the same sounds as are spoken into the microphone.

The telephone was designed in 1875 by Alexander Bell, Later on the development of the telephone changed its construction, it became more complex. Auxiliary elements were used in the circuit to provide better transmission of speech. Further on the development improved the switching system. Now very complex telephone constructions are used and a new kind of telephone appeared - radiotelephone.

Вариант 3.

Задание 1. Измените число существительных с единственного на множественное и внесите соответствующие изменения в остальные члены предложений.

1. This mountain has never been climbed before.

2. There was a potato in the basket.

3. A bird sang on the branch of a tree.

4. The guide organized excursion well.

5. This program will be shown by him.

6. That boy is my brother.

Задание 2. Измените форму прилагательных, данных в скобках, и переведите предложения на русский язык.

1. Jack is (rich) than Henry, but I don't think he is (happy),

2. He doesn't look a day (old) than forty.

3. Summer is the (warm) of the four seasons.

4. I think your plan is the (good) of the two.

5. His dog is (good) than yours.

6. His answer was (bad) than I thought,

Задание 3. Вставьте модальные глаголы may, can, must, need.

1. There are no buses or taxis, so we ... walk.

2. I.. not go out today: it is too cold

3. ... I use your telephone?

4. I ... ask the chief to put off my report: it is impossible to do anything in such a short time!

5. What time is it? It be about 6 o'clock, but I am not sure.

6. We «.. not live without food and water.

Задание 4. Поставьте глаголы, данные в скобках, в нужную форму.

1. The cafe (close) at midnight.

2. They always (talk) about literature when they see each other.

3. I (meet) him last June. :

4. He often (work) until midnight

5. I (leave) home at 8 .00 and (get) here at 15.00.

6. I (read) this book several times.

Задание 5. Переведите предложения на английский язык.

1. Прошедший год был для меня очень трудным.

2. Неделю назад в это время я ехал в поезде.

3. Служащие заканчивают работу в 6 часов вечера.

4. В школе он играл в футбол за сборную города.

5. Я понял, что вчера был не прав, и извинился.

6. Завтра мы с друзьями пойдем в кино.

Задание 6. Образуйте отрицательную и вопросительную формы предложений.

1. Child eat a lot of ice cream.

2. His brother works for Microsoft, /mort?

3. Two years later they were to be divorced.

4. He was being questioned by the police.

5. Tomorrow’s match is going to be very exciting.

Задание 7. Задайте вопросы к каждому члену предложения.

1. He’s been in hospital for a week.

2. As a racing driver he has crashed 10 cars.

3. I’ve been sitting in this waiting room for two hours.

4. He had to hand in his driving licence.

5. She should have gone to the doctor.

Задание 8. Задайте общий, специальный, альтернативный и разделительный вопросы к каждому предложению.

1. It is feared that 20 people may have died.

2. We were welcomed by the Duke.

3. He is been with this company for five years.

4. She almost fell off the ladder.

1. Sometimes he stays indoors all day long.

Задание 9. Переведите текст на русский язык.