208 Common Science 



stand a dynamo, you must first realize that there are 

 countless electrons in the world perhaps all things 

 are made entirely of them. But 

 you remember that when we want 

 to get these electrons to do work 

 we must make them flow. This 

 FIG. 114. Spinning loops of can be done by spinning a loop of 



of 



electricity to flow through net. Whenever a loop of wire is 

 turned between the two poles of a 



magnet, the magnetism pushes the electrons that are al- 

 ready in the wire around and around the loop. As long as 

 we keep the loop spinning, a current of electricity flows. 

 If only one loop of wire is spun between the poles of a 

 magnet, the current is very feeble. If you loop the wire 

 around twice, as shown in Figure 114, the magnet acts 

 on twice as much of the wire at the same time ; so the 

 current is stronger. If a very long piece of wire is used 

 and is looped around many times, and the whole coil 

 is spun rapidly between the poles of a powerful magnet, 

 myriads of the electrons in the wire rush around and 



FIG. 115. The more loops there are, the stronger the current. 



around the loops a powerful current of electricity 

 flows through the wire. 



Now suppose you bring one loop of the long wire out, 

 as shown in Figure 115, and suppose you spin the rest 



