1. ELECTRICITY

3. Electricity per person per year = 22 trillion kWh / 7 billion = 3000 kWh (United States = 14,000 kWh)

5. Originally, Electric Utilities  Vertically Integrated Regional monopolies, highly regulated This ended in 1978 with PURPA (Public Utility Regulatory Policies Act)  Divided energy industry into Generation, Transmission, and Distribution  Opened the door to independent power producers

7. Originally, Electric Utilities  Vertically Integrated Regional monopolies, highly regulated This ended in 1978 with PURPA (Public Utility Regulatory Policies Act)  Divided energy industry into Generation, Transmission, and Distribution  Opened the door to independent power producers Many states encourage transition to renewable energy sources through Renewable Energy Portfolio Standards (RPS)  Example: 10-20% of energy must come from renewable sources by a certain date

8. What is electricity?

9. Flow of electrons

10. Atomic Models

11. What are the 4 forces of the universe? Gravity Strong Nuclear Force Weak Nuclear Force Electromagnetism

12. Suppose I push against the wall…..what force am I using?

13. Electromagnetism

14. Suppose I push against the wall…..what force am I using? Electromagnetism Can I ever actually touch the wall?

15. Suppose I push against the wall…..what force am I using? Electromagnetism Can I ever actually touch the wall? No!

16. How does a flashlight work?

17. How does an electrical circuit work?

18. How does an electric car work?

20. What is the current in the circuit?

21. V = I R (Voltage = Current x Resistance)  I = 8 amps

22. Appliances in Series: If V = 120 volts and R1 and R2 are both 5 ohm, what is the current in the circuit?

23. Appliances in Series: If V = 120 volts and R1 and R2 are both 5 ohm, what is the current in the circuit? V = I R 120 = I x 10  I = 12 amps

24. Appliances in Series: If V = 120 volts and R1 and R2 are both 5 ohm, what is the current in the circuit? V = I R 120 = I x 10  I = 12 amps What happens to the voltage around the circuit?

25. Appliances in Series: If V = 120 volts and R1 and R2 are both 5 ohm, what is the current in the circuit? V = I R 120 = I x 10  I = 12 amps What happens to the voltage around the circuit? It drops in stages

26. Gullfoss, Iceland

27. Appliances in Series: What happens to the current if you keep adding resistors?

28. Appliances in Series: What happens to the current if you keep adding resistors? V = I R 120 = I x (5+5+5+5)  I = 6 amps The current drops

29. Appliances in Parallel: If V = 120 volts and R1 and R2 are both 5 ohm, what is the current in the circuit?

31. Niagara Falls

32. Appliances in Parallel: If V = 120 volts and R1 and R2 are both 5 ohm, what is the current in the circuit? 1 / Rtot = 1/5 + 1/5 1/Rtot = 2/5 Rtot = 2.5 V = I R 120 = I x 2.5  I = 48 amps

33. Appliances in Parallel: If V = 120 volts and R1 and R2 are both 5 ohm, what is the current in the circuit? 1 / Rtot = 1/5 + 1/5 1/Rtot = 2/5 Rtot = 2.5 V = I R 120 = I x 2.5  I = 48 amps What happens to the voltage across them?

34. Appliances in Parallel: If V = 120 volts and R1 and R2 are both 5 ohm, what is the current in the circuit? 1 / Rtot = 1/5 + 1/5 1/Rtot = 2/5 Rtot = 2.5 V = I R 120 = I x 2.5  I = 48 amps What happens to the voltage across them? It is the same = 120 V

35. Appliances in Parallel: What happens to the current if you keep adding resistors?

36. Appliances in Parallel: What happens to the current if you keep adding resistors? 1 / Rtot = 1/5+1/5+1/5+1/5 1/Rtot = 4/5 Rtot = 1.25 V = I R 120 = I x 1.25  I = 96 amps It increases

37. Why do you want Christmas lights to be in parallel, not series?

38. Because if one bulb fails, the whole circuit doesn’t stop

39. Why do you want Christmas lights to be in parallel, not series? Because if one bulb fails, the whole circuit doesn’t stop Why might this still be a problem?

40. Why do you want Christmas lights to be in parallel, not series? Because if one bulb fails, the whole circuit doesn’t stop Why might this still be a problem? Power delivered = volts x current P = VI P = (IR)I P = I 2 R The power increases with the square of the current, and current is greater for parallel circuits  you are more likely to blow a fuse.

41. Appliances in Parallel:

42. Table 10-2a, p. 340

49. An Electric Current in a wire generates a magnetic field rotating around it!

50.  The “right-hand rule” gives the direction

51. A Solenoid

52. A Solenoid and Bar Magnet have the same magnetic field!

54. Cylindrical convection in the outer core creates the geomagnetic field

56. https://www.youtube.com/watch?v=XU8nMKkzbT8

58. The opposite works too!!! If you move a magnet through a coil of wire, you create an electric current in the wire!!  Electricity Generator (you just need a way to move the magnet)  https://www.youtube.com/watch?v=CQSIdbY4XTU

59. Hydroelectric Turbines  use water to turn the the coils of wire through a magnetic field

61. Electricity is transmitted over high voltage lines

63. A Transformer: Converts a current at one voltage into a current in a separate circuit at a different voltage  Entirely depends on the relative numbers of coils

64. A Transformer: Converts a current at one voltage into a current in a separate circuit at a different voltage  Entirely depends on the relative numbers of coils

67. Remember….power is proportional to the square of the current: P = I 2 R The power lines have a small resistance, and so the power lost to heat will be P = I 2 R  Need to reduce the current to reduce power lost! For the Transformer, V(in) x I(in) = V(out) x I(out) If you go from 120 V to 120,000 V, your current is 1000 times less, and your power loss is a million times less!!