THE MAGNETISM OF IRON. 



75 



/ 



in Fig. 39 where a small magnet is placed in the non-uniform 

 field near the pole of a large magnet. The forces F and F' 

 are different in value and not opposite in direction. 



The attraction of a 

 particle of iron by a 

 magnet depends in the 

 first place upon the mag- 

 netization of the particle 

 of iron and in the sec- 

 ond place upon the non- 

 uniformity of the mag- 

 netic field in which the 

 magnetized particle finds 

 itself, that is to say, the 



7 ' Fig. 39. 



particle of iron becomes 



a magnet and its two poles are acted upon by unequal forces 



on account of the non-uniformity of the field. 



^^.^te< {&&!?> 



s^-^jf^sa 



5 _ ^-Tvrv^W 



fe^^rw^l 

 I^^^^S^ 



. 



Fig. 40. 



Fig. 41. 



The magnetic field near a flat-ended magnet pole is approxi- 

 mately uniform (lines of force parallel straight lines) as shown in 

 Fig. 40 ; near the sharp corners of the pole, however, the field is 

 distinctly non-uniform (lines of force diverge strongly). Therefore 

 particles of iron are not perceptibly attracted by the flat-face of the 

 pole whereas the sharp corners of the pole attract particles of iron 



