90 



coil with the same cell, and state whether more or fewer 

 filings adhere than before. 



The lifting power of a coil can be increased by sending 

 more current through it, and by winding it closer. To try 

 the effect of increased current, connect the coil with two 

 or three cells instead of one. 



A coil of wire having an iron core and traversed by an 

 electric current is called an electromagnet. In factories 

 where much metal is used, the metal shavings and clip- 

 pings are often raised from the floor by electromagnets. 



EXPERIMENT 87. THE ELECTRIC BELL 



Connect an electric 

 bell to a cell (repre- 

 sented by ) as 

 Cell shown in Figure 68. 

 If the bell is large and 

 the cell is weak, the 

 current may not be 

 strong enough to ring the bell. In 

 this case, use several cells, getting their 

 combined effect by joining them as in 

 Figure 69. 



m 



y 



000 



FIG. 68. The electric bell. 



FlG. 69. A battery of cells. 



