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Current Electricity

Current Electricity. e-. P. n. nucleus. Electrons. Electrons Flow. Conventional Current. Flow of Electrons (Path). -. +. e -. e -. e -. e -. e -. e -. e -. e -. e -. e -. Conventional Current. Flows from + to -. e. e. e. e. e. Current. Flow of Electrons.

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Current Electricity

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  1. Current Electricity

  2. e- P n nucleus Electrons

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

  4. Conventional Current Flows from + to -

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

  6. e e e e e e e e e e e e e e e e Current Flow of charge (q)! q - Coulomb(C) 6.24 X 1018 electrons

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

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

  9. Charge Time Q t Current = I = Current

  10. Coulomb Second Ampere = C S 1 A = 1 Current

  11. e e e e e e e e e e e e e e e e Force 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. Load Source Path Putting it all Together

  19. I _ V R + Schematic Diagram Path Source Load

  20. I _ V R + Mathematical Equation V = IR

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

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

  23. V VR I = I R Ohm’s Law Wheel Find: I

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

  25. I _ R=500Ω V=10v + Example

  26. V I R VR 10V500Ω I = = Example Given: V=10v R=500Ω Find: I = ? Equation: 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. P I V Power Wheel Find: P P = IV

  32. P PV I = I V Power Wheel Find: I

  33. P PI V = I V Power Wheel Find: V

  34. V P V2R I I V R P = Power Equations P = IV P = I2R

  35. Conductor Switch Fuse Capacitor Resistor Variable Resistor Schematic Symbols

  36. Battery dc generator Ammeter A Connection No Connection Ground Schematic Symbols Voltmeter V

  37. Schematic Diagrams

  38. R1 _ V R2 V + A Schematic Diagrams

  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 = IVt E = I2Rt E = (V2/R)t

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

  43. V2t R E = (100V)2(60s) 500Ω E = Example Given: V=100v R=500Ω t=1min=60s Find: E = ? Equation: = 1200J

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

  45. Transmission ofElectric Energy Minimize Power Losses P = I2R 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 X106 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

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