Тексты для профессионально-ориентированного обучения по теме "Физические явления" (естественно-научный профиль)

The nature of matter

Everything around us consists of matter: a book, your body, the air you breathe, and the water you drink. Matter is anything that has weight or mass and takes up space.

All matter may be classified as either solid, liquid, or gas. Solids are firm and have a definite form. Rubber, wood, glass, iron, cotton, and sand are all classified as solids. A considerable force would be needed to change the shape of volume of an iron bar, for example, because the atoms or moiecules of a solid are densely packed and have very little freedeom of movement.

Solids may be further devided into 2 classes: crystelline and amorphous. Crystalline solids (rocks, woode, paper etc,) are made up of atoms arranged in a definite pattern. When these solids are heated, they change to a liquid, known as melting, is sharp and clear. In amorphous substances (rubber, glass and suifur), the pattern of the atoms is not orderly, and when heated, they gradually soften.

Liquids are not rigid. The atoms or molecules of liquids attract each other and thereby enable liquids to flow. But these atoms are loosely structured and do not keep their shape. Therefore a liquid will take the shape of any container in which it is poured, however, liquids have a definite volume: a quart of milk cannot fit in a pint container.

Gases, such as air, o9xugen, and carbon dioxid, have no fixed shape or volume of their own. They diffuse or spread out to fill any container. The atoms or molecules of gases are widely spaced and move very rapidly, they either compress or expand to adapt to any area.

The nature of matter

Vocabulary

to consist - состоять

matter — вещество, материал

weight - вес

solid - твёрдый

liquid - жидкий

definite - определённый

considerable - значительный

force - сила

shape - размер

volume - объём

densely - плотно

movement — движение, подвижность

crystelline - кристаллический

amorphous - аморфный

pattern — образец, модель

melting - плавление

to soften — смягчать, размягчаться

rigid — жёсткий, твёрдый

attract — привлекать, притягивать

loosely - свободно

to pour - наливать

however — тем не менее, несмотря на

oxygen - кислород

carbon dioxid — углекислый газ

to diffuse — рассеивать(ся)

to spread out - распространять(ся)

widely - широко

rapidly - быстро

to compress - сжимать(ся)

to expand - расширять(ся)

to adapt to - приспосабливать(ся)

area — площадь, зона

Electrical conductivity

Matter is frequently classified according to its electrical copnductivity as a conductor, nonconductor, or semiconductor. Conductors have many electrons that are free to move and are useful in carrying, or conducting, electric current,. All metals, particularly silver, copper, gold, and aluminum, are good conductors. Substances with few free electrons are called nonconductors, or insulators, because they do not carry electric charge and can be used to prevent electricity from flowing where it is not wanted. Air, wood, glass, and plastic are insulators. A few substances, like carbon, silicon, and germanium, do not fall into either of these categories. They are classed as semiconductors and are used in such electronic devices and transistor radios.