MAGNETS 



243 



IRON FILINGS SHOW THE 

 FIELD ABOUT A MAGNET 



thus mapped out is called a line of force. These lines of 



force about a good magnet are very numerous. 

 A convenient way of study- ^^^^^f 



ing the field around a magnet 



is to place the magnet under a 



piece of paper covered with iron 



filings. The filings will form 



curves joining the N and S 



poles of a bar magnet, and 



some lines will go out from 



each pole which do not seem to 



join one another. If a horse- 

 shoe magnet is used, we find 



lines of force going straight across from the N pole to the 



S pole and also lines going in the opposite direction. 



If opposite poles, N 

 and S, of two bar mag- 

 nets are placed near each 

 other under a piece of 

 paper on which iron fil- 

 ings are sprinkled, it will 

 be found that lines of 

 force join the two mag- 

 nets much the same as 

 the lines joined the two 

 poles of the same mag- 

 net. Now reverse one 

 of the two magnets so 

 that an N pole is near 

 an N pole, and sprinkle 

 iron filings over the 

 paper again. Observe 

 that lines of force do not 





FIELD ABOUT N AND S POLES OF Two 



MAGNETS, SHOWING LINES OF 



ATTRACTION 



