THE ELECTRIC CURRENT. 



poles NN and 55 turns the coil until this side force is balanced 

 by the action of the hair-spring. 



The magnetic effect of the electric current which is shown in 

 its simplest aspect in Fig. 2, is exemplified in the Morse tele- 



Fig. 3a.- 



Fig. 3b. 



graph. A battery B t Fig. 4, is connected through a long line 

 so as to send current through a wire which is wound on an iron 

 rod RR at a distant station. A device K, called a key, is 

 arranged for opening and closing the circuit through which the 

 electric current flows, and the rod RR is magnetized every time 



r~K~ 



r-Wi 



line wire 



ground return 



Fig. 4. 



the key is closed, thus causing the rod RR to attract a small 

 bar of iron / which is attached to a pivoted lever A ; and when 

 the key K is opened, the rod RR loses its magnetism and 

 ceases to attract the iron 7. In this way the pivoted lever A is 

 caused to move back and forth with the opening and closing of 



