III. Choose the necessary word

l. His work must be (achieved, completed) as soon as possible.

2. Our laboratory needs (expansion, knowledge).

3. The car (deeply, suddenly) stopped in the middle of the street.

4. A lot of different experiments are performed at the (library, theatre, laboratory).

5. The students believe that they will be given any opportunity (to go on, to stop).

6. The laboratory has modern (date, facilities and tasks).

7. The tunnel is (under, between, over) the ground.

 8. The building of this new institute has been completed (tomorrow, recently, two months ago).

 

IV. Finish the sentences.

1. The storage battery is………….

2. Electric current is………………

3. When the engine is running at normal speed……………………..

4. When the engine is running very slowly…………………

5. Any current used to……………..

6. A charged battery consists of………………….

7. When the two plates are connected into a circuit……………………

8. A battery's capacity is…………..

 

V. Make steams of synonyms

l.aim, 2. Struggle, 3. Also, 4.job, 5. End, 6. General, 7.common, 8. Too, 9. Reduce, 10. Opportunity, 11. ' Employment, 12. Purposeless, 13. Fight, 14. Decrease, 15. Purpose, 16. Work, 17. Finish, 18. Possibility, 19. Aimless, 20. Occupation.

VI. Translate sentences, pay attention to the underlined words "outside of", "out of".

1.This is beyond the power of scientists. 2. These errors are beyond the control of the operator. 3. Do you know what is beyond the Earth's atmosphere. 4. These are the points which lie off these lines. 5. The major effects off the testing area are unknown. 6. Point P. Is outside the circle. 7. Outside the low buildings one can see an extensive area of virgin lands.8. Beyond this range it is necessary to use inorganic materials. 9. These elements have a single electron outside the closed shells. 10. It would be difficult to maintain radio contact with a rocket much beyond the boundaries of the aclar system.

 

VII. Answer following questions

1. What is the storage battery?

2. What purposes is the storage battery used for?

3. How does the storage battery and the generator interact?

4. What is the simple example of how a battery works?

5. What is the construction of storage battery?

6. How does the battery work?

7. How can we know the capacity of a battery?

 

ПРАКТИЧЕСКАЯ РАБОТА № 25

HOW GENERATOR WORKS

Цель: Введение и активизация лексики по теме «Как работает генератор».

Оборудование: комплект тестов, раздаточный материал, иллюстрации по теме.

Vocabulary

I. Learn the words and expressions.

 

a bar                             брусок, плитка

south and north poles       южный и северный полюса

to be generated                 порождаться, производиться

external circuit                  внешняя цепь

at right angle                    под прямым углом

to rotate                             вращать(ся)

a revolution                       вращение, оборот

an armature coil               якорная обмотка

in slots                               в пазах

to be soldered                    быть спаянным

semicircular segments       полукруглые части

to be-insulated                 быть изолированным

to be in series                     быть последовательно соединенным

pulsating current              пульсирующий ток

upwards of                        свыше

II. Read and translate the text.

How Generator Works

Parti

There are lines of forces between two bar magnets, that is between south and north poles. If aconductor is moved at right angles to the lines of force, a voltage will be generated in the wire, causing acurrent to flow through the wire and through the external circuit. No voltage is produced in the conductorwhen it moves parallel to the lines of force, because no lines of force are cut.

When a conductor is rotating in a field, it cuts a maximum number of lines of force when moving at right angles to them, and cuts no lines when moving parallel to them. During the rotation of a conductor from the parallel to right angle position the number of lines of force cut is gradually increased from nothing to the maximum. Like wiso when the conductor rotates from the right angle position to parallel, the number of lines cut is decreased from maximum to nothing. Voltage and current rise and fall occurs endlessly during all the half revolutions through which the conductors are rotated.

Part 2

The construction of the simple generator is as follows. The single armature coil is located in slots in a cylindrical piece of soft steel called the armature core. The ends of the coil are soldered to semicircles segments of copper to from the "commutator". The two segments are insulated from each other. Two copper composition "brushes" are pressed against the commutator, thus providing electrical contact when commutator and armature coil are rotated. The brushes do not rotate.

The magnetic field is produced electrically by coils of wire which are wound around the iron "field poles". The two coils are in serious and are connected to the brushes. The external circuit is also connected to the brushes. Current flows out into the external circuit through the positive (+) brush and returns by way of the negative (-) brush to the armature coil.

When the armature coil is moving, there is a rise in voltage and current from zero to a maximum, and then when the coil moves, there is a drop in current and voltage from a maximum to zero.

Instead to the pulsating current produced by a single armature coil, a smooth current is desirable and this obtained by increasing the number of coil on the armature. An actual generator has upwards of 2fl. coils.