396 



GENERAL SCIENCE 



will be seen to move, and the direction it takes will depend upon the 

 direction the magnet is moving in the coil. This shows us how 

 electricity is generated. We have already learned that radiating 

 from the magnet are lines of magnetic force. As the magnet moves 

 in the coil these lines of force are cut bv the wires, and the current 



FIG. 276. Thunder Storm. E, earth charged near the surface by minus 

 electricity. Why? A , cloud charged with plus electricity, C, church, trees 

 and house, charged with minus electricity. The man, the cow, the water, 

 and all objects on the earth are charged with minus electricity during a 

 thunder storm. Why does the lightning "strike" the church or tree 

 rather than the cow or ground? Why is the interior of the earth charged 

 with plus electricity during a storm? Why is the left side of B and the 

 right side +? 



of electricity is induced in the wire. The commercial dynamo is 

 built on the same principle. Coils of wire on the armature are 

 rotated in front of powerful magnets. In order to make the magnets 

 more powerful all the current generated by the dynamo is allowed 

 to pass through the wires around the magnet. This is called a series- 



