Переведите и запомните следующие слова и словосочетания. discovery, application, development, property, limitation, superconductor, convenience, programming; copper-iron machine

discovery, application, development, property, limitation, superconductor, convenience, programming; copper-iron machine, electromagnetic machine, electrical- power applications, magnetic fields, dominant factor, power/ weight ratio, automatic washing machine, method of producing mechanical power, different set of limits.

2.8.2 Прочтите и переведите текст; расскажите о назначении galvanic battery и copper-iron machine

1. Before Faraday's discoveries the only usable source of electricity was the galvanic battery, and it made possible some practical applications, including the electric light and the electric telegraph. But the practical supply of electricity on a large scale was only possible by the development of electromagnetic machines, generators and transformers.

2. For the use of electricity to produce mechanical power where it is wanted, another electromagnetic machine – the electric motor – still remains the most effective method.

3. What made all this possible? It needed not only the discovery and understanding of the basic laws (by Faraday), but also the discovery of materials with suitable properties. It is really very fortunate that high magnetic fields can be sustained in a material as cheap as iron. Without iron, the whole economics of electromagnetic machines and of electrical-power applications would be quite different.

4. The electromagnetic machine is still developing in other respects. Using iron, it is cheap to produce the magnetic field, but an important limitation is imposed by saturation. This limit can be overcome by using superconductors at very low temperatures to carry very high currents and produce much stronger magnetic fields – without using iron. This development opens up a new field for machine designs and applications, and it offers a different set of limits from those of the copper-iron machine.

5. Nevertheless, the copper-iron machine is so simple and reliable that it is likely to continue for a very long time as the main method of producing mechanical power.

For many applications, the dominant factors are not efficiency and

power/weight ratio but convenience and cleanliness, and with electricity one is really buying convenience rather than power. It seems likely that the main advances in domestic applications will be by developments of control and programming to give even greater convenience, a good present example being the automatic washing machine.

6. The electric motor is a superb machine to provide power, and its applications must expand for that reason alone.

Примечание

power/weight ratio – мощность на единицу веса (двигателя)

Date: 2016-02-19; view: 876; Нарушение авторских прав