1. The capacity to absorb heat varies between substances.

2. Each object in nature has a particular temperature which can be compared with the temperature of other objects.

3. To make this comparison accurate thermometer is used.

4. Each atom is known to have a name and symbol.

5. To know the melting point of the metal in use is necessary.

6. I consider him to be the best qualified person in the laboratory.

7. Whenever the speed or velocity of a body changes, the body is said to have acceleration.

8. Laws and theories are formulated from the results of the experiments and then used to predict the results of new experiments.

Batteries

An Italian scientist Alessandro Volta made a` lot of experiments with electricity. Batteries as sources of electrical energy are the result of his experiments.

Today battery cells are produced in two common forms: dry cells, used in flashlights, portable radios, clocks, cameras and (well) wet cells, used in automobiles, airplanes, boats.

The voltaic cell is composed of three parts: a pair of dissimilar metal plates called electrodes, a dilute acid solution called electrolyte, and a nonconducting container called the cell. In a glass container filled with sulphuric acid there are two plates: one copper and are connected by a copper wire, electricity will flow through it from the copper plate to the zinc plate.

For the voltaic cell the copper plate is the positive electrode and the zinc plate the negative electrode a copper wire will convey electricity and is called an electrical conductor. Copper, aluminium and silver are good conductors. They must be surrounded by protective material which does not conduct electricity. Such materials are called electrical insulators (glass, wood, rubber, some plastics, insulation tape)

Remember that faulty insulation is dangerous and leads to unwanted electrical flow and probably to local overheating.

Words to the text

1. Source-источник

2. Cell-элемент

3. Flashlight-сигнальный огонь

4. Plate-пластинка

5. Acid-кислота

6. Copper-медь

7. Wire-проволока, провод

8. Insulator-изолятор

9. Rubber-резина, каучук

10. Tape-лента, тесьма

11. To use-использовать

12. To compose-составлять

13. To fill-наполнять

14. To connect-соединять

15. To flow-течь

16. To convey-переправлять

17. To surround-окружать

18. To remember-помнить

19. Common-общий, частый

20. Portable-переносной

21. Dry-сухой

22. Wet-мокрый

23. Dissimilar-несходный

24. Sulphuric-серный

25. Faulty-неисправный

26. Dangerous-опасный

Вставьте пропущенные слова

1. A battery is a source of ….

2. Battery cells are manufactured in ….

3. The voltaic cell is composed of ….

4. Cells connected together form ….

5. The positive electrode is ….

6. The negative electrode is ….

7. Series connection means ….

8. Materials which do not conduct electricity are called ….

Electrical, insulators, two common forms, electrical energy, copper plate, Zink plate, three parts, battery, the terminal of one cell is connected to

Electrical Measuring Units and Instruments

Any instrument which measures electrical values is called a meter. An ammeter measures the current in amperes. The unit is named after Andre Marie Ampere, a French scientist. A voltmeter measures the voltage and the potential difference in volts. The volt is named after Alessandro Volta, an Italian scientist.

The current in a conductor is determined by two things, the voltage across the conductor. The unit by which resistance is measured is called the ohm. The resistance in practice is measured with the ohmmeter, a wattmeter measures electrical power in watts. Very delicate ammeters are often used for measuring very small currents. Whenever an ammeter or voltmeter is connected to a circuit to measure electric current or potential difference the ammeter must be connected in series and the voltmeter in parallel.

Answer the questions

1. What does an ammeter measure?

2. Was Andre m. ampere a French or Italian scientist?

3. How is the current in a conductor determined?

4. What is the unit called by which resistance is measured?

5. Does a wattmeter measure electrical power?

6. How does an ammeter measure electric current?