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HOW WE PRODUCE ELECTRICITY 



find that they cling to each other as well as to the magnet. 

 If you separate the magnet from the nails which are 

 touching it, all the nails will immediately cease clinging 

 to each other. Magnetized nails may cause other objects 

 such as soft iron or tacks to become magnetized for a 

 time, but as soon as they are loosened from the perma- 

 nent magnet, they lose their magnetic properties. Even 

 permanent magnets may lose their power after a while, 



especially if they are 

 heated. Permanent 

 magnets are made 

 of steel or of some 

 alloys of steel ; tem- 

 porary magnets are 

 made of soft iron. 



What Happens to 

 a Suspended Mag- 

 net? Take a long bar 

 magnet and suspend 

 it by an untwisted 



Can a bar magnet be substituted for a compass? gtrmg g() that it 



swing in a horizontal plane. It will take a position in a 

 north-south line. We may check this with a compass. 

 That end of the magnet pointing north is called the north- 

 seeking or north pole, and the other end is called the 

 south-seeking or south pole of the magnet. Since all 

 magnets have this property, a magnetic needle is used in 

 the mariner's compass. 



How to Make a Compass. Magnetize a needle by rub- 

 bing it on a bar magnet. Cut off a thin sheet of cork and 

 float the cork in a dish of water. Lay this magnetized 

 needle on the cork. What position does it take? Put 

 a needle that is not magnetized on the cork. Does it 

 act in the same way ? How could you find east and west 

 if you had a compass ? 



