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Electricity and magnetism

Electricity and magnetism. Nobel prize: graphene. Andre Geim. University of Manchester. Konstantin Novoselov. The unit of electric current is the: Volt Amp Coulomb Ohm Watt. Did you read the assignment>? Yes No. A superconductor is a material that: Has lots of electrons

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Electricity and magnetism

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  1. Electricity and magnetism

  2. Nobel prize: graphene Andre Geim University of Manchester Konstantin Novoselov

  3. The unit of electric current is the: • Volt • Amp • Coulomb • Ohm • Watt

  4. Did you read the assignment>? • Yes • No

  5. A superconductor is a material that: • Has lots of electrons • Insulates your home • Has zero resistance • Nobody has created yet • Has extremely high voltage

  6. Heat engines  electricity

  7. The basics of electrostatics

  8. Two equal mass balls are charged, and hang on strings as shown: What can we conclude about the signs of Q1 and Q2? A: One is "+", the other is "-" B: Both are "+" C: Both are "-" D: Both must be the same charge (but we can't tell if they're both "+", or both "-")

  9. Two uncharged conducting spheres, A and B, are suspended from insulating threads so that they touch each other. While a negatively charged rod is held near, but not touching sphere A, the two spheres are separated. How will the spheres be charged, if at all? Sphere A Sphere B A) 0 + B) - + C) 0 0 D) - 0 E) + - B A

  10. An electron traveling horizontally enters a region where a uniform electric field is directed upward. What is the direction of the force exerted on the electron once it has entered the field? A) to the left B) to the right C) upward D) downward E) out of the screen

  11. Pick up here Oct 14

  12. If we put bunch of electrons in a box, they will A) clump together. B) spread out uniformly across box. C) make a layer on walls. D) do something else.

  13. Voltage? Voltage is the energy per charge.

  14. CRT: Cathode ray tube (tv)

  15. Current Amount of charge I = = time Current is the flow of electric charges.

  16. Why isn’t this bird toast? • The bird understands quantum physics • The wire has no current running through it • The bird’s other leg isn’t touching the ground • Wires are insulated for safety – people walk up to wires and touch them too with no problem

  17. Resistance

  18. IA IB • Which current is bigger? • IA • IB • They are the same

  19. R R is big resistance r is small resistance IB r IA • Which current is bigger? • IA • IB • They are the same

  20. Tues Oct 19 pick up here

  21. Opinions about circuit stuff Are the conceptual circuit sims (PhE`T) that we’ve been playing with helpful? • Yes • No • Sort of…

  22. Opinions about circuit stuff What about the ones I’ve drawn on the board — helpful? • Yes • No • Sort of…

  23. Opinions about circuit stuff Are our exercises helping you to see how electricity ‘works’ in our lives? • Yes • No • Sort of…

  24. Opinions about circuit stuff Would more math help you to see what’s happening? • Yes • No • Not sure

  25. Opinions about circuit stuff How well do you understand voltage, current, and resistance? • I can build a computer from scratch now • I can explain all of the examples that we’ve been through • I have a grasp on most of the concepts • I might struggle if you asked me a question like “which lightbulb is brighter” in a circuit with 2 or 3 bulbs and a battery • I’m actually kind of lost

  26. Opinions about circuit stuff How much longer do you want to spend on this stuff? • I want more time to explore and discuss with other students • I want more instruction • I want to move on to new stuff

  27. Worksheet on circuits for next week’s hw? • Yes please • No! • Just make it optional

  28. Other feedback?

  29. Resistance

  30. Table of resistivities

  31. Surface mount devices

  32. Review… IA IB V • Which current is bigger? • IA • IB • They are the same

  33. Review… r R V • Which voltage drop is bigger? • Across r • Across R • They are the same

  34. R R is big resistance r is small resistance IB r V IA • Which voltage drop is bigger? • Across r • Across R • They are the same

  35. R R V

  36. R R #2 V R R #1 • Which circuit has brighter light bulbs? • #1 • #2 • All light bulbs are the same brightness V

  37. R R R V V #2 #1 • Which circuit has brighter light bulbs? • #1 • #2 • All light bulbs are the same brightness

  38. Capacitor

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