Exercises

Energy

Text 2

Retell the text.

Make an outline of the text.

Put six general questions to the text.

Active Words and Expressions

ability – способность, возможность hydroelectric station – гидроэлектростанция

forms of energy – формы энергии to drive – приводить в движение

heat – тепловая turbine – турбина

mechanical – механическая to produce – производить, создавать,

electrical – электрическая (электро) порождать

chemical – химическая in one’s turn – в свою очередь

atomic – атомная to employ – использовать, применять

kind – вид, род source – источник

potential – потенциальная (скрытая) battery – батарея, гальванический элемент

kinetic – кинетическая generator – источник энергии, генератор

to change – менять, превращаться solar – солнечная

to turn – меняться, превращаться to harness – использовать

waterfall – водопад semiconductor – полупроводник

Scientifically speaking, energy is the ability to do work. There are various forms of energy, such as: heat, mechanical, electrical, chemical, atomic and so on. One might also mention the two kinds of mechanical energy – potential and kinetic, potential energy being energy of position while kinetic energy is energy of motion. It is well known that one form of energy can be changed into another.

Take a waterfall as an example. Water falling from its raised position, energy changes from potential to kinetic. If there is a hydroelectric station at the waterfall, the energy of the falling water is used to drive the turbines. The turbines, driven by the kinetic energy of the running water, turn electric generators, these generators producing electric energy. Thus, the mechanical energy of falling water is turned into electric energy. The electric energy, in its turn, may be transformed into any other necessary form.

When an object loses its potential energy, that energy is turned into kinetic energy. Thus, in the above-mentioned example when water is falling from its raised position, it certainly loses its potential energy, that energy changing into kinetic energy.

We have already seen that energy of some kind must be employed to generate the electric current. The sources of energy usually employed to produce current are either chemical, as in the battery, or mechanical, as in the electromagnetic generator. Chemical sources of current having a limited application, the great quantities of electric energy generated today come from various forms of mechanical energy.

Needless to say that rising standards of modern civilization and growing industrial applications result in an increasing need of energy. Every year we need more and more electric energy for the useful things that are done only owing to electricity. However, the energy sources of the world are decreasing at the same time as the energy needs of the world are increasing. These needs will continue to grow as more motors and melted metals are used in industry and more electric current is employed in our everyday life. As a result, it is necessary to find new sources of energy.

The sun is an unlimited source of energy. However, at present, only a little part of solar energy is being used directly. How can we employ solar energy directly to produce useful energy? This is a question which has interested scientists and inventors for a long time. Lavoisier and other great scientists of the past melted metals with the help of solar furnaces. Today solar furnaces illustrate just one of the numerous ways to harness the sun. Using semiconductors, scientists, for example, have transformed solar energy into electric energy.

Дата добавления: 2015-05-08