MAGNETIC MATERIALS 175 



68. Steel Magnets. 



Magnets which are made by man 

 are called artificial and are much 

 stronger than the natural magnets. 

 All artificial magnets are made from 

 steel. A straight magnet is called a 

 bar magnet, while a straight bar, 

 which has been bent into the form 

 of a horseshoe, is called a horseshoe 

 magnet. The illustration shows a 

 horseshoe magnet. The chief ad- 

 vantage of this form is that both 

 poles can pull upon or attract the 

 same piece of iron. The piece of 

 iron, which is shown across the 

 poles of the horseshoe magnet, is 

 called a keeper. It retains or keeps 

 the magnetic strength. 



Experiment 73. Magnetic Materials. 



Apparatus: A bar magnet, pieces of every kind of 

 material you can find, sheet of paper, thin piece of wood, 

 piece of window glass and any sheet metal. 



a. Try to pick up pieces of every kind of material 

 with your magnet. What can you pick up with it? If 

 you try to pick up a piece of tin with the magnet you 

 must remember that "tin" is iron covered with tin. Iron 

 is sometimes covered or plated with copper and brass. 

 What are your final conclusions in regard to the kind of 

 material which is attracted by a magnet? 



