2.  There are two kinds of electric charge : positive and negative.  Like charges repel & unlike charges attract.

3.  When a balloon is rubbed against your hair, some of your hair’s electrons are transferred to the balloon.  The positive charge on your hair is equal in magnitude to the negative charge on the balloon.

4.  When an object is charged, its charge is always a multiple of a fundamental unit of charge : e  This means charge is quantized.

5.  Conductors : material in which electric charges move freely. › Ex: (most metals) copper, aluminum  Charge can be done by › Contact ex: A balloon becomes charged when you rub it on your hair. › Induction ex:

6.  Insulators : materials in which electric charges do not move freely. › Ex: glass, rubber, silk, plastic  Charge can be done by contact or polarization.  Polarization ex:

7.  Electric force is a field force between two charged objects causing motion either toward or away from each other.  The closer two charges are, they greater the force between them.  This is represented by Coulomb’s Law.

8. F electric = Newtons (N) kC = 8.99 x10 9 q = Coulomb (C) r = meters (m)

9.  Open books to pg. 635  Sample Problem 17A