1. Coulomb’s Law Electric Force and Electric Field

4. Coulomb's Law

5. Vector form of Coulomb’s Law Q1 Q2 r 12 r 12 is a vector connecting the two charges. is a unit vector in this direction + + + -

6. Sample Problem Resultant F on P = F BP – F AP = 2.62  10 -5 N. Direction: To the left (attraction) P B A + - + 6 cm 4 cm 2 nC 5 nC 1 nC

7. Force from many charges Superposition

8. Force from many charges Q1 Force on charge is vector sum of forces from all charges Principle of superposition + - Q2 + Q4 - Q3