Magnetism and Electricity 



199 



You might expect a 

 " negative charge " to 

 indicate fewer electrons 

 than usual, not more. 

 But people called the 

 charge " negative " long 

 before they knew any- 

 thing about electrons ; 

 and it is easier to keep 

 the old name than to 

 change all the books that 

 have been written about 

 electricity. So we still 

 call a charge " negative " 

 when there are unusually 

 many electrons, and we FIG 

 call it " positive " when 



The charged comb picks -up 

 pieces of paper. 



there are unusually few. 



A negative charge means that more electrons are present 

 than usual. A positive charge means that fewer elec- 

 trons are present than usual. 



Before you rubbed your comb on wool, neither the 

 comb nor the wool was charged ; both had just the 

 usual number of electrons. But when you rubbed them 

 together, you rubbed some of the electrons off the wool 

 on to the comb. Then the comb had a negative charge ; 

 that is, it had too many electrons too many little 

 particles of electricity. 



When you brought the comb near the hair, the hair 

 had fewer electrons than the comb. Whenever one 

 object has more electrons on it than another, the two 



