STATIC ELECTRICITY 133 



force of the current in the conductor that connects 

 them, and the greater is the ability of this current to 

 flow against resistance. 



QUESTIONS 



1. Why is electricity important to man? What, in general, 

 may be studied regarding electrical energy? 



2. How is electrical energy made? What forms of energy are 

 commonly used for the purpose ? 



3. What is a conductor? What is an insulator ? Name exam- 

 ples of conductors and of insulators. Why should some insulators 

 (as wood or cloth) become good conductors when wet ? 



4. Show the use of conductors and insulators in controlling 

 electrical energy. What might happen if air were a good con- 

 ductor ? 



5. Name the four general electric effects. Name uses to which 

 each of these is put. 



6. What is meant by potential ? What is high potential and 

 low potential ? To what is potential somewhat similar. ? 



7. By what means is a current kept up? Explain fully the 

 meaning of electro-motive force. How can the electro-motive 

 force of a current be increased and decreased? 



SECTION II 

 STATIC ELECTRICITY 



157. Electric Charges. Some substances, such as 

 glass, resin, silk and woolen cloth, when rubbed with 

 other bodies of a similar nature, behave in a peculiar 

 manner, as we may have noted. For example : a glass 

 rod rubbed with silk cloth will pick up bits of paper; 

 the dry hair sometimes seems drawn toward a rubber 

 comb that is run through it, or seems inclined to " stand 



