122 GALVANIC ELECTRICITY. 



currents moving in the same general direction, attract 

 each other, while those moving in opposite directions, 

 repel. 



What is the 290. MUTUAL ACTION OF COIL AND MAG- 



mutual action NET jf a floating magnet be substituted 



of a coil and 



magnet? for one of the coils, in the above ex- 



periment, the result is not in the least affected. 

 They act toward each other precisely as if both 

 were magnets, or both, coils. 



291. ACTION OF A SINGLE WIRE ON 



What is the . , 



action of sin- A COIL. A single wire, carrying a cur- 



yle wire on a rent actg Qn & fl oatm cr co il in the same 

 magnetic coil r 



manner. Stretched above it, as in- 

 dicated in the figure, the north pole of the coil 

 will move to the right. The motion is such as to bring 

 adjacent currents, in the wire, and in the coil, to co- 

 incide in direction. 



292. POLARITY OF THE COIL IMPARTED 



What effect f 



has the mag- TO IRON. A bar of soft iron placed in 

 neticcoil upon t k Q -i b ecornes itself a magnet, and re- 



metals ? 



ceives the name of electro-magnet. Great- 

 er power is acquired if the metal is, closely 

 wound with copper wire, covered with cotton 3 

 to prevent any lateral passage of the current. 

 The horse-shoe shape, in which the poles are 

 brought round near to each other, is the more 

 common. The power of such magnets contin-' 

 tinues only while the current is passing. Electro- p 

 magnets have been constructed capable of lifting a ton, 

 or even more. They are sometimes employed in dress- 

 ing iron ores, to separate, by their attraction, the work- 



