1. Current Electricity

2. Electrons P n nucleus e-

3. Flow of Electrons (Path) e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- e-e- - + Electrons Flow Conventional Current e-e-

4. Flows from +to-

5. Current Flow of Electrons Metals - Free Electrons e ee ee

6. Current Flow of charge (q)! q - Coulomb(C) 6.24 X 10 18 electrons eeeeee ee e e eeeeee

7. Current eeeeee ee e e eeeeee Amount of charge passing a point in a second.

8. Current Symbol - I Unit – Ampere (Amps) Amperes - A Current = ChargeTime

9. Current ChargeTime I = Qt

10. Current Ampere = CoulombSecond 1 A = 1 1 A = 1CS

11. Force eeeeee ee e e eeeeee Voltage Potential Difference Electromotive Force (EMF)

12. Source of Electrons(Force)

13. Voltage Symbol - V Unit – Volt Volt - V

14. Resistance Opposition to Current Flow High Resistance Insulator

15. Resistance Opposition to Current Flow Low Resistance Conductor

16. Resistance Opposition to Current Flow High and Low Resistance SemiConductor

17. Resistance Symbol - R Unit – Ohm Ohm - Ω

18. Putting it all Together Load Source Path

19. Schematic Diagram I _ + VR Source Path Load

20. Mathematical Equation I _ + VR V = IR

21. Ohm’s Law The mathematical relationship between Current, Voltage and Resistance.

22. Ohm’s Law Wheel RI V Find: V V = IR

23. Ohm’s Law Wheel RI V Find: I I = VRVR

24. Ohm’s Law Wheel RI V Find: V R = V I

25. Example I _ + V=10v R=500Ω

26. Example Given: V=10v R=500Ω RI V Find: I = ? I = VRVR Equation: = 10V 500Ω I = 0.02A = 20mA

27. Homework:22-1 Prob: 1,3,4,8,9, 11,14,17,20 Page 526, 527 Due: 3/20/07

28. Power Power measures the rate at which energy is transferred. In the case of electric current, charge is being transferred

29. Power Symbol - P Unit – Watt Watt - W

30. Power Power = Current X Voltage P = IV

31. Power Wheel VI P Find: P P = IV

32. Power Wheel VI P Find: I I = PVPV

33. Power Wheel VI P Find: V V = PIPI

34. Power Equations VI P P = V2RV2R RI V P = IV P = I 2 R

35. Schematic Symbols Conductor Switch Fuse Capacitor Resistor Variable Resistor

36. Schematic Symbols Battery dc generator V Voltmeter A Ammeter ConnectionNo Connection Ground

37. Schematic Diagrams

38. V _ + R2R2 R1R1 V A

39. Meter Placement Voltmeters are placed parallel to the component being measured. Ammeters are placed in series with the component being measured.

40. Using Electric Energy Energy used in an Electric Circuit. P = E/t E = Pt

41. Using Electric Energy E = I 2 Rt E = IVt E = (V 2 /R)t

42. Example _ + V=100v R=500Ω How much energy is used in 1minute???

43. Example Given: V=100v R=500Ω t=1min=60s Find: E = ? E = V 2 t R Equation: E = (100V) 2 (60s) 500Ω 1200J = 1200J

44. Homework:22-2 Practice Problems: 11-17 Page 517, 522 Due: 5/29/03

45. Transmission of Electric Energy Minimize Power Losses P = I 2 R Decrease Current Increase Voltage - 500,000V

46. The Kilowatt-Hour The Electric Company charges you for the amount of energy in Kilowatt-Hours. A Kilowatt-Hour is equal to 1000W delivered continuously for 1 hour(3600s).

47. The Kilowatt-Hour 1kWh = (1000W)(1 hour) 1kWh = (1000J/s)(3600s) 1kWh = 3.6 X10 6 J E = Pt

48. Kilowatt-Hour Example A TV set draws 2.0A at 120V when operating. If the set is on 5 hours a day for 30 days, how much does it cost to run the set? 1 kilowatt-hour cost $0.12.

49. Kilowatt-Hour Example Given: V=120v I=2A t=(5h/day)(30days) t=150h Find: E = ? Cost

50. Kilowatt-Hour Example Equation: E = Pt E = Ivt E = (2A)(120V)(150h) E = 35000Wh = 35kWh Cost = (35kWh)($0.12) Cost = $4.20

51. Homework:22-3 Practice Problems: 18-20 Section Review Page: 525 Due: 5/30/03