1. Electricity & Magnetism Part I Static Electricity

2. Unit 10 Concept Map Electricity and Magnetism Static ElectricityCurrent ElectricityMagnetism & Electromagnetism

3. The Electrical Charge Carrier The Electron –Negatively charged –9.11x10 -31 kg The Proton –Positively charged –1.67x10 -27 kg Why is the electron principally responsible in determining electric charge?

4. Charge Basics  Opposite charges attract  Like charges repel  Electrons and protons have equal and opposite charges  Lowest possible charge is that of electron or proton (no fractional charges…yet)

5. Benjamin Franklin 1706-1790 Famous kite experiment First to give charges the names positive and negative First to realize Law of Conservation of Charge Invented the lightning rod

6. The SI Unit of Charge The Coulomb (C)  6.25x10 18 electrons (or protons) are needed to make one Coulomb The charge on one single electron/proton  1.6x10 -19 C See reference table for values

7. Charles-Augustin de Coulomb 1736-1806

8. Questions? How does an object become negatively charged? How does an object become positively charged? What is the net charge in Coulombs of 5 electrons? What is the number of protons that make up a charge of 10 nanoCoulombs?

9. Law of Conservation of Charge Electric charge can neither be created nor destroyed -5 -11 -8

10. Transferring Charge

11. The Electroscope A device used to detect electric charge

12. Charging by Induction Isolating charge without physical contact between objects Once charged rod is removed, the electroscope stays neutrally charged

13. Charging by Conduction Isolating electric charge by physical contact Once rod is removed, the electroscope remains charged

14. Permanently Charging by Induction

15. Coulomb’s Law There exists an electrostatic force between charged objects that is directly proportional to the magnitude of the charges and indirectly proportional to the square of the distance between them. There exists an electrostatic force between charged objects that is directly proportional to the magnitude of the charges and indirectly proportional to the square of the distance between them. This is another Inverse-Square law This is another Inverse-Square law This force could be attractive or repulsive This force could be attractive or repulsive

16. Coulomb’s Law F 21 indicates force on q 1 due to q 2 F 12 indicates force on q 2 due to q 1

17. Coulomb’s Law

18. Coulomb’s Constant

19. Let’s Try a Problem F 21 indicates force on q 1 due to q 2

20. The Van de Graaff Generator Generates large static charges that build up on dome Some generators can charge to thousands of volts They are generally safe, but caution should be heeded

22. Electric Fields An electric field is an invisible force field that affects electric charges The field is defined based on how it affects a positive test-charge All charged objects are assumed to have an electric field associated with them

23. Electric Field Mapping

24. Electric Field Around a Positively Charged Object

25. Electric Field Around Charged Pairs

26. Electric Field of a Set of Parallel Plates

27. Electric Field Mapping Rules E-Field lines must never touch or cross themselves or other field lines E-Field lines run out of a positive charge and into a negative charge E-Field lines must intersect charged object at right angle (90 o ) Number and density of lines indicate field strength or intensity

28. Electric Field Intensity Units of electric field intensity are Newtons per Coulomb q represents charge on test-charge

29. Electric Field Equation for Point Charges Capital Q indicates charge on the object

30. Electric Potential Energy Electric potential energy is the energy stored within an electric field The work done in moving a charge within an electric field is equal to the potential energy stored The kinetic energy gained by a charged particle within an electric field is equal to the potential energy lost What are the units for EPE?

32. Work-Energy Theorem Review

33. Electric Potential Electric potential is the ratio of the work done on a charged particle within an electric field divided by the particle’s charge Units are Joules per Coulomb Other terms used for electric potential are electric potential difference and voltage

34. Electric Potential Units of Electric Potential are Joules per Coulomb or Volts

36. Electric Fields Within a Charged Object

37. Potential Inside a Conductor

38. Electric Field of a Set of Parallel Plates

39. The Capacitor Capacitor Uses –Frequency tuner –Power supplies –Filter –Block DC current

40. Capacitance of Parallel Plates

41. Capacitance (in terms of Charge and Voltage)

42. Millikan Oil Drop Experiment

43. E & M Part 2 Current Electricity Current Resistance Voltage Ohm’s Law Power Circuits –Series –Parallel

44. Electric Current Time rate of flow of electric charge I represents electric current Units of current are Coulombs per second

45. Electrical Resistance The opposition to steady electric current flow The unit of resistance is the Ohm (  Similar to friction there is no such thing as zero resistance Carbon Resistor

46. Resistance in Electrical Conductors i.e. wires Resistance depends on: –Length of wire –Thickness of wire –Type of material used (metal) –Temperature –How do you think each one of these parameters effects resistance?

47. Resistance in Electrical Conductors R is resistance L is wire length A is cross-sectional area  is resistivity of conductor

48. Resistance of Electrical Conductors Wire Gauges Area Length

49. Resistivity Table

50. The Simple Circuit Needed for circuit –Voltage source –Complete path –Load

51. Electrical Circuit Analogy Battery Light Bulb

52. Schematic Symbols

53. Electron-Flow Current

56. Series Circuit Circuit that has only one path for current to flow.

57. Series Circuit Analogy Battery

58. Series Circuit Schematic

59. Series Circuit Equations

60. Parallel Circuit Circuit that has more than one path for current to flow.

61. Parallel Circuit Analogy Battery

62. Parallel Circuit Schematic

63. Parallel Circuit Equations

64. Kirchoff’s Law of Current The current going into a junction (node) is equal to the current coming out ???????? Which one of these is correct?

65. Electrical Safety Never Intentionally take a shock!

66. Electrical Safety Remove Jewelry, watches, rings, etc.

67. Electrical Safety Use one hand (if possible) on live circuit

68. Electrical Safety Strictly follow lab instructions

69. Electrical Safety Absolutely NO HORSING AROUND!!!

70. Electrical Safety Remember: Current KILLS, not Voltage –5–5 mA = 0.005 ASensation felt –1–15 mA = 0.015 APainful –2–20 mA = 0.020 ALoss of muscle control –1–100 mA = 0.100 AHeart fibrillation –2–200 mA = 0.200 ASevere burns, Death

71. Resistor Color Code