1. Chapter 20
Static Electricity

2. Calculate: 6.4 x 10274 x 1.5 x 10-162  8.0 x 10-254  7.5 x 10175 x 2.0 x 10-225 =

3. The study of charges that can be collected and held in one place
Electrostatics
The study of charges that can be collected and held in one place

4. Come up with examples where charge differences build up in nature, and describe the consequences

5. Caused by an electron imbalance as electrons move
Charge
Caused by an electron imbalance as electrons move

6. In neutral atoms the number of electrons = the number of protons
Atomic Charge
In neutral atoms the number of electrons = the number of protons

7. Opposite charges attract & like charges repel

8. The charge of an object leaks off into water molecules in air

9. Charged objects eventually return to their neutral state

10. Holding a charge is easy on dry days & difficult on humid days

11. Materials like metals that allow electrons or charges to move
Conductors
Materials like metals that allow electrons or charges to move

12. Copper, silver, gold, aluminum, & graphite
Common Conductors
Copper, silver, gold, aluminum, & graphite

13. Materials that will not allow electrons or charges to move easily
Insulators
Materials that will not allow electrons or charges to move easily

14. Glass, dry wood, plastic, rubber, & dry air
Common Insulators
Glass, dry wood, plastic, rubber, & dry air

15. Anything that can absorb lots of electrons
Electron Sink
Anything that can absorb lots of electrons

16. Common Electron Sinks
People, Earth, etc

17. A device used to detect electrical charge
Electroscope
A device used to detect electrical charge

18. Define:
Conductor
Insulator
Electron Sink

19. Charge Redistribution
Conduction
Induction

20. Charge by touching a charged body to a neutral body
Charge by Conduction
Charge by touching a charged body to a neutral body

21. Charge by moving a charged body near a neutral body
Charge by Induction
Charge by moving a charged body near a neutral body

22. Charge Separation on Neutral Objects

23. - - - + - - - + - - - + - + - + - + + + - + + + - + + +

24. - - - + - - - + - - - + - + - + - + + + - + + + - + + +

25. Force caused by the attraction or repulsion of charges
Electrical Force
Force caused by the attraction or repulsion of charges

26. Electrical force must be much greater than gravitational force

27. Coulomb’s Law
Force between charges is proportional to charge & inversely proportional to distance between charges

28. Coulomb’s Law
F  qAqB

29. Coulomb’s Law 1 d2
F 

30. Coulomb’s Law
qAqB d2
F 

31. Fe Formula
qAqB
dAB2
Fe = K

32. Electric Constant
9.0 x 109 Nm2 C2
K =

33. Identify another formula that is very similar to the electrical force formula

34. Define: Charge by Induction Charge by Conduction

35. Gravity Formula
mAmB
dAB2
Fg = G

36. Calculate the electrical force occurring when a ball with a charge of 2.0 x 10-8 C is 12 mm from another ball with a charge of -3.0 x 10-8 C:

37. Calculate the electrical force occurring when a ball with a charge of 3.0 x 10-4 C is 12 mm from another ball with a charge of -6.0 x 10-6 C:

38. Millikens Oil Droplet Experiment

39. + plate
Fup
Fup = Fdown
Fdown
qoqp d2
m1m2 d2
Fdown = G = mg
Fup = K

40. qoqp d2
K = mg
mgd2
Kqp
qo =

41. Electron Charge
1.60 x C
C = Coulombs

42. Calculate the force between 2 electrons 8.0 x 10-3 nm apart:

43. Calculate the force between the electron & the nucleus of hydrogen: 4
Calculate the force between the electron & the nucleus of hydrogen: 4.0 x 10-2 nm apart:

44. Calculate: Fe on B dAB = 4.0 mm dBC = 3.0 mm qA = - 4.0 x 10-5 C
qB = 3.0 x 10-5 C
qC = 9.0 x 10-5 C

45. Calculate the force between 2 particles 1.2 x 10-3 mm apart:
q1 = 4.0 x 10-5C
q2 = x 10-4C

46. Calculate: Fe on A dAB = 4.0 mm dBC = 3.0 mm qA = - 4.0 x 10-5 C
qB = 3.0 x 10-5 C
qC = 9.0 x 10-5 C

47. Calculate: Fe on C dAB = 4.0 mm dBC = 3.0 mm qA = -4.0 x 10-2 C
qB = 3.0 x 10-2 C
qC = 6.0 x 10-2 C

48. Calculate the charge of a particle 3
Calculate the charge of a particle 3.0 mm away from a magnet that can produce a force of N with a charge of C.

49. Calculate: Fe on B dAB = 5.0 mm dBC = 10.0 mm qA = -4.0 x 10-3 C
qB = 3.0 x 10-3 C
qC = 6.0 x 10-3 C C

50. Explain, on the atomic level, how any substance can build up an electric charge.

51. Calculate: Fe on C dAC = 5.0 nm dBC = 3.0 nm qA = 4.0 x 10-3 C
qB = 3.0 x 10-3 C
qC = 5.0 x 10-3 C

52. Calculate: Fe on B dAB = 6.0 nm dBC = 5.0 nm qA = 4.0 x 10-3 Cg B C
qA = 4.0 x 10-3 C
= 44o
= 37o
= 40o
Small = 30o
qB = 3.0 x 10-3 C
qC = 5.0 x 10-3 C

53. Explain how to attain a charge & the conditions necessary for attaining that charge.