MAGNETS 



241 



N 



INDUCED MAGNETISM WITH AND 

 WITHOUT CONTACT 



tacks will drop from the first one, since they do not 

 retain the magnetism, and act as magnets only while in 

 the presence of the bar magnet from which they ob- 

 tained their force. Any piece 

 of soft iron may be thus mag- 

 netized temporarily by holding 

 it in contact with a permanent 

 magnet; but actual contact is 

 not even necessary. Present 

 some iron filings to one end of a soft iron nail while a 

 magnet is held near the other end of the nail. It will 

 be found that the nail will act as a magnet and hold 

 some of the filings. Now lay a piece of glass on some 

 filings or tacks and touch the glass with the end of a 

 good bar magnet, then lift the magnet and glass and see 

 how many tacks are held to the glass by the magnet. 

 Remove the magnet from the glass and the tacks will 

 drop. Several sheets of paper may be used in place of 

 glass and the result will be the same. Magnetism pro- 

 duced by such methods, with or without contact, is called 

 induced magnetism. 



When a nail is near a magnet, it becomes a magnet by 

 induction. If the N pole of a magnet is placed near a 



nail, the end of the nail near 

 the magnet becomes an 5 pole 

 and the other end of the nail 

 becomes an N pole. The mag- 

 net will then pick up the nail, 

 because two unlike poles attract 

 each other. (See the law of 



magnets.) The particles of iron filings become magnets 

 by induction also when in the field of a magnet. The N 

 pole of one particle attracts the S pole of the particle 



SUCCESSIVE MAGNETIC 

 INDUCTION 



