3.2- charged materials, opposites attract, like charges repel

negative charges

-the charges of electrons

surrounds the nucleus; can be rubbed off a material

positive charges

the charges of protons

- part of the nucleus of atoms are held firmly in place

charging by friction

when electrons are rubbed off, it is postively charged

-material gains electrons and become negatively charged

uncharged materials

before 2 materials are rubbed together: they have equal numbers of positively charged and negatively charged electrons

-they are electrically neutral (cancel each other out)

charged materials

-If electrons rubbed off one material, the protons stay behind and the material becomes positively charged

-the material that gains electrons also become charged

-charged material have unequal number of + and - charges

rule

opposites attract, like charges repel

balloon ex.

-when a charged object (balloon) is brought to a neutral object (wall), the electrons dont come off

-negative charges in wall are pushed from the surface by the neg charges on balloon

-pos ends of molecules on wall are attracted to the negative charges on balloon

-the attraction is strong enough to hold the balloon to the wall

what is the law of electric charge

explains why charged objects attracts neutral objects

why does the van de graff generator make our hair stick up

when u put your hand on it, your body becomes charged, you hair is all negatively charged, making the strands repel, pushing away from each other