INDUCED MAGNETISM 179 



The illustration shows an experiment which you 

 should repeat for yourself. 

 Take a nail and hold it near a 

 magnet but not touching it. 

 The nail will then attract iron 

 filings. Remove the magnet 

 and the nail loses its magnet- 

 ism. Magnetism which is 

 caused in this manner is called 

 induced magnetism. Magnet- 

 ism must be induced in an object before it can be 

 attracted by a magnet. Since iron is the only common 

 material which can have magnetism induced in it, it is 

 the only common metal which can be attracted. Steel 

 is made from iron and retains its magnetism better than 

 iron because it is harder. Electricity can produce in 

 iron much stronger magnetism than can exist in steel 

 magnets. We shall learn about this next year. 



Review Questions, 28. 



1. What are the advantages of sunlight? 



2. What is the proper method of heating water, 

 from above or from below? Explain. 



3. How do fishes live in the water? Do plants help 

 fishes? Do plants help man? Explain fully. 



4. Why do we eat? Why do w r e drink? When do 

 we need to eat fat? When do we need to drink a large 

 amount of water? 



5. Name some plants which are harmful to man. 

 What can we do to prevent these plants from harming 

 us? 



