1. Voltage Chapter 3

2. Voltage (V or E) Supplies the force or pressure required to move electrons through a circuit. Unit – Volt (V) AKA – Electromotive Force EMF

3. Voltage Sources Friction – Van de Graaf Generator

4. Voltage Source Generator – Most Common

5. Voltage Source Cell – Battery: Chemical Reaction

6. Voltage Source Photovoltaic Cell Light → Voltage

7. Voltage Source Thermocouple Heat → Voltage

8. Voltage Source Piezoelectric Effect Pressure → Voltage

9. Cells and Batteries Primary Cells Cannot be Recharged

10. Cells and Batteries Secondary Cells Can be Recharged

11. Connecting Voltage Sources Series Aiding Series Opposing - - + + - - + +

12. Voltage Sources Voltage sources added in Series increase the Voltage and the Current stays the same. V = 1.5v I = 1A V = 4.5v I = 1A

13. V = 4.5v I = 1A

14. Voltage Sources Voltage sources added in Parallel increase the Current and the Voltage stays the same. V = 1.5v I = 1A V = 1.5v I = 3A

15. V=1.5v I =3A

16. Example Example Battery: V = 1.5v, I = 1A V=3v I= 3A V=3v I=1A

17. V=3v I=3A

18. Battery: V = 1.5v and I = 100mA 9v 100mA V T = 9v I T =500mA V T = 9v and I T = 500ma

19. V T = 9v I T =500mA

20. Voltage Rise Voltage Rise can be defined as the energy added to a circuit.

21. Voltage Drop A Voltage Drop is defined as the energy removed or used in a circuit.

22. Voltage Drop

23. Earth Ground Zero Voltage reference point. Limits build up of electrical charge. Limits exposure to high voltages.

24. Electrical Ground Ground is defined as the zero reference point which against all voltages are measured.

25. Electrical Ground in a Car

26. Jumping a Car Bad Battery

27. Ohm’s Law The Current(I) in a circuit is directly proportional to the Voltage(E,V) and inversely proportional to the Resistance(R). I = VRVR

28. Ohm’s Law RI V Find: V V = I x R

29. Ohm’s Law RI V Find: R R = V/I

30. Ohm’s Law RI V Find: I I = V/R

31. Ohm’s Law Units RΩRΩ IAIA VvVv

32. RkΩRkΩ ImAImA V (v)

33. Ohm’s Law Units RMΩRMΩ IμAIμA V (v)

34. Ohm’s Law Example RΩRΩ IAIA VvVv R=2Ω, V=12v Find: I I = V/R =12v/2Ω I = 6A

35. Ohm’s Law Example RkΩRkΩ I mA VvVv V=120, I=60mA Find: R R = V/I =120v/60mA R = 2kΩ

36. Ohm’s Law Example RkΩRkΩ I mA VvVv R=10kΩ, I=12mA Find: V V = I x R =12mA x 10kΩ V = 120v

37. Wheel of Answers RΩRΩ IAIA VvVv R kΩ I mA VvVv

38. Power Power is how fast work is done. Work is done when force causes motion. Electric Force: Voltage Moving: Electrons

39. Power Power: P Unit for Power: Watt Watt: W P = IV

40. Power Law VI P Find: P P = I x V

41. Power Law VI P Find: V V = P/I

42. Power Law VI P Find: I I = P/V

43. Power Law Units V IAIA PWPW

44. V ImAImA P mW

45. How much power does a 12V computer fan use if it is drawing 1.5A? V = 12V I = 1.5A P=IV P=(1.5A)(12V) P = (18W)

46. Combining Ohm’s and Power Laws RI V P = I 2 R V2 RV2 R P =

47. Classwork Read the following Chapters: Read the following Chapters: »Chapter 2: All »Chapter 3: All »Chapter 4: Pages 32-44 »Chapter 5: Pages 49-52 Answer the questions after each section: Answer the questions after each section: Write down question and answer!!! Perform Self-Test at the end of the chapter Perform Self-Test at the end of the chapter Write down question and answer!!!