VII. Discuss with your group-mates.

1. We know that an atom is made from protons and neutrons in a nucleus, and electrons spinning around this nucleus. The protons have a positive electric charge and the electrons have a negative electric charge. The neutrons have no electric charge. As the electrons spin around the nucleus, they produce small currents. These currents create a magnetic field around the electrons and the atom. This magnetic field makes the atom behave like a small magnet.

2. Magnets can be natural or artificial. The Earth, for example, contains magnetic substances in its nucleus. These substances, which are also in our body, make our planet a big natural magnet. That’s why when you hang a bar magnet from a thread in a horizontal position, its north pole points to the geographic north pole of the Earth. A bar magnet is an artificial magnet. This type of magnets are usually made from a combination of elements that contain iron, cobalt or nickel.

3. Iron does not always behave like a magnet and this is because its atoms are usually disorganised. A needle, for example, that contains iron is not a magnet (A) but when you rub the needle with a magnet, its atoms line up and the needle becomes a magnet (B). The needle can then attract other metals. This property of some substances to attract metals is called magnetism.

4. Electromagnetism and gravity are two basic forces of nature. They are very similar and scientists are trying to unify them. Electromagnetism works in small objects – it attracts the electrons from the atomic nucleus and maintains them in place. Gravity works with big objects – the pull of gravity from the nucleus of the Earth maintains our atmosphere in place. Both, the electrons and the Earth, spin and generate an electric and a magnetic field around them. These fields make up our planet’s electromagnetic shield.

Vocabulary

IV. Remember these words:

property, to generate, needle, bar, point, to maintain, charge, iron, to attract, field.

Grammar

V. Look for words in the text derived from the nouns below. Identify, if it’s a noun or an adjective.

Example: gravity – gravitational (adj.)

1. Magnet ________

2. Atom ________

3. Geography ________

4. Electron ________

5. Sphere ________

VI. From the words given below form adjectives using the following suffixes:

a) -able

to change, to consider, to suit, to move, to compare, to control, to represent;

b) -ous

danger, advantage, to vary, to continue;

c) -less

doubt, form, wire, regard, use, help, hope;

d) -al

industry, centre, culture, form, nation, mechanics.

VII. Translate the following words and define the meaning of their prefixes:

disproportional, indifferent, impossible, to reheat, preheat, overload, to miscalculate, reaction, to misunderstand, irregular, dissimilar, supercritical, undoubtedly, impractical, disproportional, misdirection, immeasurable.

Thomas Alva Edison

Reading

I. Read the following words:

technical, laboratory, due, humanity, throughout, further, contribution, public, genius, widespread.

Date: 2015-12-11; view: 1657