General suggestions for the care and use of storage batteries

1. Always have the terminals clean and bright and make good tight connection when installing a battery to use it for starting. Good connections are necessary to carry the heavy current used in starting an engine.

2. A battery should be charged at least once every two months when not in use.

3. Never bring an open flame near a battery when it is being charged (hydrogen gas mixed with air is explosive).

4. In cold weather do not add water to a battery except immediately before charging.

5. Never add acid to the electrolyte in a battery. The acid in a battery does not deteriorate, only water evaporates.

6. Always keep the level of the electrolyte above the lop of the plates by adding distilled water.

7. Electrolyte will burn holes in clothing.

8. The effect of a splash of electrolyte on clothing or skin may he neutralized by ammonia water if it is applied immediately.

 

                 TEST YOURSELF

Упр. 1. Подберите правильные переводы для слов левой колонки.

1. overload                      1. предел

2. alloy                            2. перегрузка

3. spark                          3. удалять

4. range                         4. делить

5. remove               5. указывать

6. prevent               6. искра

7. indicate              7. плавить

                                         8. сплав

                                         9. предотвращать

                                         10. рассматривать

 

Упр. 2. Подберите правильные переводы для слов левой колонки.

1. part                         1. содержать

2. path                              2. выпрямлять

3. assemble                      3. иметь место

4. contain               4. чинить

5. level                             5. часть

6. rectify                        6. путь

7. occur                         7. проходить

                                         8. уровень

                                         9. собирать

                                         10. тащить

 

Упр. 3. Укажите номера предложений, в которых слово «cause» переводится как «заставлять».

1. What causes the electrons lo flow along the wire?

2. Heating causes many chemical changes.

3. There must be a potential difference to cause electrons to move through the metal conductor.

4. Different reactions cause chemical changes.

5. The cause of charging is now to be discussed,

6. Pressure causes ice to melt.

7. What causes a body to move?

 

Упр. 4. Укажите номера предложений, в которых слово «provided» является союзом.

1. Provided we use the necessary instruments, the measurement will always he correct.

2. Automation provided the control of not only individual machines but also whole shops and even factories,

3. Lightning protection is provided by the installation of lightning conductors.

4. The electric current flows provided there is a complete circuit.

5. These electrical devices can work for a long time, provided they are made of good materials,

6. These electrical devices are provided with rubber insulator.

7. The students will be able to translate difficult articles, provided they have a dictionary.

Упр. 6. Переведите следующие предложения.

1. We are to take into consideration all advantages and disadvantages to decide what system is the bestfor future work,

2. One should know that the Ohm is the practical unit of resistance.

3. This machine can be stopped at any moment.

4. You ought to have paid more attention to the problem of fuel consumption.

 

                                      * * * * *

                          

                    UNIT VI. Measuring devices.

Lesson 1.

Text.

                        Measuring devices.

Ammeters and Voltmeters. — Ammeters measure the cur­rent flowing in a circuit and normally have scales which are graduated or calibrated in amperes, milliamperes or micro­amperes.

Voltmeters are used to measure the potential difference be­tween two points in a circuit. The calibration of voltmeters is usually in volts, millivolts, or microvolts.The main difference between the two instruments of the same type or design is in the resistance of the operating coil, identical moving units may be used for either meter. An am­meter is connected in the positive or negative lead in series with a circuit and, therefore, must have a lоw resistance coil, otherwise the readings would be incorrect as the coil would ab­sorb an appreciable amount of power.

A voltmeter is connected in parallel across the points of a circuit where the difference of potential is to be measured. The resistance of the operating coil must, in this instance, be as high as possible, to limit the amount of current consumed by it, or else a drop in potential due to the meter would occur and the pointer indication would not represent the true poten­tial difference across the circuit.

Wattmeters. — The measurement of the power in a D. C. circuit at any instant can be achieved by means of an ammeter and voltmeter as the power in watts is the product of the current and the voltage. With A. C. circuits, however, the in­stantaneous values are always changing. To measure A. C. power correctly, therefore, it is necessary to use the third in­strument to measure the phase difference. The normal practice, however, is to combine these three instruments in one which will give a direct reading of power in watts.

Words and word combinations:

ammeter - амперметр

voltmeter – вольтметр

wattmeter – ваттметр

graduate – градуировать, сгущать жидкость

calibrate – калибровать, проверять

normally - обычно

of the same type or design — одного и того же типа или конструкции                                

identical moving units may be used for either meter — одинаковые подвижные части могут использоваться для любого из этих измерительных приборов       

positive or negative lead — положительный или отрицательный подводящий

проводник

in series — последовательно    

otherwise the readings   would be incorrect — в противном случае показания были бы неверными  

is to be measured — должна измеряться   

in this instance — в этом случае        

as high as possible — как можно выше

consumed by it — им потребляемый

or else — иначеa

drop in potential — падение потенциала

due to — из-за

across the circuit — в данных точках цепи

at any instant — в любой момент

by means of — посредством

is the product of – является произведением

the instantaneous values — мгновенные значения

direct reading — непосредственно показание

Assignment:

   I. Find the antonyms to the following words, translate them into Russian:    

       

   Positive, normally,    instrument,   connect, across, incorrect,

   high.

II. Make up all types of questions to the sentences:

    1. A voltmeter is connected in parallel across the points of a circuit.

    2. The resistance of the operating coil must be as high as possible.

 

        I II. Make up 7 different questions to the text.

                                  

Lesson 2.

Text.

                            Electroscope.

An electroscope is a sensitive instrument for detecting small electric charges. It consists of a glass-jar closed with a stopper of insulating material in which is fitted a varnished glass-tube. A rod passes through the tube. At the top of the rod there is a metal ball or disc and at the bottom of the rod two pieces of gold leaf are suspended. When a charge is brought near the electroscope, a charge of opposite sign is induced on the metal ball, and a charge of the same sign appears on the two of the gold leaves. Since the two pieces of gold leaf now have charges of like sign, they repel each other

As an example a negatively charged glass rod is brought to the electroscope. A positive charge is induced on the ball and a negative charge appears on the two pieces of gold leaf.

The polarity of a charge may be determined by means of an electroscope. We charge the electroscope negatively by touching the ball with a rod of hard rubber which is rubbed with flannel or silk. If the unknown charge is brought to the electroscope it will induce on the ball a charge of opposite polarity, and on the gold leaves a charge of the same polarity as that of the unknown charge. Therefore, if the unknown charge is negative, the gold leaves will repel each other; if it is positive, they will attract.

Words and word combinations

Sensitive – чувствительный

glass-jar – стеклянный сосуд

a stopper of insulating material — пробка из изоляционного материала                                    

is induced on — индуцируется на

varnished-glass lube — покрытая лаком стеклянная трубка

charge of like sign — одноименный заряд

by means of — посредством  

Assignment:

I. Find in the text the following words and word combinations:

              Может определяться при помощи, чувствительный прибор, положительный заряд индуцируется, проходит через трубку, две части золотой пластины, потереть кусочком фланели или шелка, состоит из, неизвестный заряд.