1 A magnet is a substance which attracts certain other substances. 2 A substance which is attracted by a magnet can itself be made into a magnet.
3 Generally speaking, there are three substances which are attracted by a magnet: iron, cobalt and nickel. 4 Substances which are attracted by a magnet are known as magnetic substances, and those which are not are referred to as non-magnetic substances. 5 Iron, cobalt and nickel are magnetic substances. 6 They are attracted by magnets and they can themselves be magnetized.
7 Mixtures of metals, or alloys, which contain a magnetic substance generally also have magnetic properties. 8 Some alloys containing none of the above metals, however, are also magnetic. 9 Certains alloys containing manganese, aluminium and copper belong to this class. 10 They are magnetic, even though they contain no metal which is itself magnetic.
11 A magnet will attract a magnetic substance like iron. 12 Not all parts of a magnet, however, have equal attractive force. 13 If a bar magnet is placed in iron filings, most of the filings will stick to the ends of the magnet, and very few will adhere to the central part. 14 The force of attraction, or magnetic force, is concentrated near the ends of the magnet. 15 These areas are known as the poles.
16 A magnet sets in a definite direction when freely suspended. 17 If a bar magnet is suspended by a thread and allowed to move freely, it will come to rest with one pole pointing towards the south. 18 The pole pointing towards the north is called the north-seeking, or north, pole; and that which points towards the south the south-seeking, or south, pole.
19 If the north poles of two freely suspended magnets are brought into proximity, so that they are close together, the ends of the two magnets will swing away from each other. 20 If on the other hand the north pole of one magnet is brought close to the south pole of the other, the two ends will attract each other. 21 A north pole will attract a south pole and repel another north pole, and be attracted by a south pole and repelled by another north pole. 22 Like* poles repel one another and unlike** poles attract one another.
From "English for Scientific Classes"
* similar -
I/ True or not true?
a) A magnet attracts other substances.
b) Iron, cobalt and nickel are the three substances which are attracted by a magnet.
c) Cobalt can be made into a magnet.
d) Alloys which contain a magnetic substance are always magnetic.
e) Manganese is a non-magnetic substance.
f) Alloys containing aluminium are magnetic.
g) The central part of a bar magnet has no magnetic force.
h) Most of the magnetic force in a magnet is near the poles.
i) A south pole will attract a north pole.
j) A north pole and a south pole are like poles.
k) Two magnets freely suspended will swing away from each other when they are brought close together.
II/ Contextual reference
1. In sentence 8, the above metals refers to: (a) Iron, cobalt and nickel. (b) Alloys.
2. In sentence 9, this class refers to: (a) The class of alloys which contain a magnetic substance. (b) The class of alloys which contain no iron, cobalt or nickel but are magnetic. (c) The class of alloys which contain manganese, aluminium and copper.
3. In sentence 10, they refers to: (a) Manganese, aluminium and copper. (b) Certain alloys containing manganese, aluminium and copper.
4. In sentence 15, these areas refers to: (a) The force of attraction (b) The ends of the magnet.
5. In sentence 19, they refers to: (a) The north poles. (b) The two magnets.
III/ Paragraph writing
Stage 1: sentence building: Join each of the ten groups of words below into one sentence, using the additional material at the beginning of each group. Omit words in italics. Number your sentences and begin each one with a capital letter.
1. MAGNETIZED/ SO THAT/ UPRIGHT/ WITH/ PROTRUDING/, AND/ HORIZONTALLY
Place a knitting needle in a cork/ it will float in a trough of water/ its north pole will just protrude out of the cork/ support a bar magnet above the water
2. THAT/; / (1797-1867)/ TO/ OF/ WHAT/ SURROUNDING
it is important to realize this/ lines of force have no objective existence/ they were suggested by Michael Faraday/ they give a mental picture/ something is happening in the space/ the space surrounds a magnet
3. FLOATING/ WITH ITS/ AND/ IT
put the needle near the magnet/ the north pole of the needle will be near the north pole of the magnet/ release the needle
4. THE EXISTENCE OF/ BY A SIMPLE EXPERIMENT
lines of force exist/ this may be demonstrated
5. TO THE SOUTH POLE OF THE MAGNET
the needle will travel along a curved path
6. TO/ DIFFERENT/, AND/SO
a diagram can be drawn/ the diagram will represent the paths/ the paths are traced out by the needle/ the lines are drawn/ the lines indicate lines of magnetic force
7. ; THAT IS, / TEND TO/ WHICH
the forces act along definite lines/ magnetic poles will be driven along certain lines/ these lines are called lines of force
8. AS/ AN INDEPENDENT/ WHEN/ IT/ FREE TO MOVE
we can define a line of magnetic force/ a line of magnetic force is the path of a needle/ the path is traced out by a north pole/ the north pole is under the influence of a magnet
9. THE/ ROUND A MAGNET/ CALLED
this area is a magnetic field
10. IF/ WITH/, / ALWAYS/, BUT
the experiment is repeated/ the needle will be in different starting positions/ the starting positions will be near the north pole of the magnet/ the needle will travel to the south pole/ the needle will travel along different paths
Stage 2: Paragraph building
Rewrite the ten sentences in a logical order to make a paragraph. Before you write the paragraphs, add the following material:
- write 'within this field' at the beginning of sentence 7
- When you have written your paragraph, re-read it and make sure that the sentences are presented in a logical order.