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Welcome to 2049

Welcome to 2049. 2049. Dr. Jeffrey B. Bindell bindell@physics.ucf.edu www.physics.ucf.edu/~bindell. Class Meets Monday, Wednesday, Friday 9:30-10:20 AM. Textbook Physics f or Engineers and Scientists Volume II (Electricity and Magnetism) Serway & Jewitt Thompson – Brooks/Cole (2004).

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Welcome to 2049

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  1. Welcome to 2049 2049 Dr. Jeffrey B. Bindell bindell@physics.ucf.edu www.physics.ucf.edu/~bindell 2049 Charge - Electric Field CH 23

  2. Class MeetsMonday, Wednesday, Friday9:30-10:20 AM 2049 Charge - Electric Field CH 23

  3. TextbookPhysics for Engineers and ScientistsVolume II (Electricity and Magnetism) Serway & JewittThompson – Brooks/Cole (2004) 2049 Charge - Electric Field CH 23

  4. General Information Instructor: Dr. Jeffrey BindellSchedule M,W,F 9:30 AM to 10:20 AM Room 359Phone 407-823-4194E-mail: bindell@physics.ucf.eduWebsite: www.physics.ucf.edu/~bindell OFFICE HOURS: M,W,F 7:30-9:30 AM 11:30-12:30 (Pot Luck) MAP-417 2049 Charge - Electric Field CH 23

  5. This is a HARD Course! Reminder 2049 Charge - Electric Field CH 23

  6. Grades 2049 Charge - Electric Field CH 23

  7. Homework It is important to notice that homework counts for 15% of your grade. Homeworks will be based on WebAssign. Although “extensions” will be available, valid reasons should be offered at the time or he request. There will be one or two assignments per chapter. Each assignment will contain between 5 and 12 problems (usually). You must complete the assignment before the due time or you must request an extension. You will need a reason. 2049 Charge - Electric Field CH 23

  8. No Curve 2049 Charge - Electric Field CH 23

  9. Approximate Exam Schedule 2049 Charge - Electric Field CH 23

  10. TENTATIVE 2049 Charge - Electric Field CH 23

  11. WebAssign • You need to purchase a WebAssign login either from the bookstore or from the WebAssign website (with credit card). • For your first contact with WebAssign, go to: http://www.webassign.net/info/support/access_codes.html • Follow the guides to purchase a registration or to Login. The left side of the page has a scroll down menu that should get you where you need to get. • Be sure to bookmark the final login screen because you will be using it quite a bit (I hope). • Your login ID is your PIN with (or possibly without) the leading “0” and without any letters from your first name. Your password has been set to “ihatephysics”. After a successful login, be sure to change your password to something else to protect the privacy of your account. 2049 Charge - Electric Field CH 23

  12. ratemyprofessors.com Completely unforgiving. Unhelpful office hours from which you leave more confused and with more questions than you came with. Seems to have no time for students, will not listen to any excuse, reasonable or not. Do not be 1 minute late on quiz day. Family emergency, car trouble= unforgivable sin Very difficult. Not in a tough way, but in an unhelpful way. Does not go over problems and his office hours are not helpful at all. You leave just as confused. Does not go over tests.  2049 Charge - Electric Field CH 23

  13. ratemyprofessors.com Waiting for grades to come in. Have no idea if I passes or failed. Tests are UNFAIR, GRADING IS UNFAIR. I didn't miss more than a day of class. This class is an experiment and I don't like being the guinea pig when my GPA is on the line. Something better give or EVERYONE in the class will fail.  This was a SCALE-UP Course 2049 Charge - Electric Field CH 23

  14. ratemyprofessors.com this class sucks, but bindell makes it doable. He answers ?'s, speaks clearly, and is pretty funny too. Fair tests and decent curves for the final grade. Do your webassign and make yourself known, you will pass this class...  Very hard class.Tests consist of 1 homework problem and 2 unseen problems, one easy, one hard.If you go to office hours(if you can get him on a day he's there)he will usually give you extra points on tests that TA's graded unfairly. He also curves the grades a lot.I was looking at a C and made an A  2049 Charge - Electric Field CH 23

  15. ratemyprofessors.com Tough class. Bindell is a funny guy and does a pretty good job teaching. Just make sure that you study and don't fall behind.  Physics II is hard, no doubting that. But Jeff is by far a VERY reasonable professor. Speaks clearly, reasonable weekly quizzes, very flexible with webassigns, and wants the class to do well. Here is something I learned the hard way: STUDY HARD FOR THE TESTS, IF YOU DO NOT, YOU WILL FAIL THEM. PERIOD.  It is men like this that keep UCF from being considered an elite public uninversity. The man is comepletely and utterly ingorant of how to convey a concept to another human being. He wont answer questions. His tests are not representative of the material. He will show you reviews such as this and refute them. Don't listen. Get out at all costs.  2049 Charge - Electric Field CH 23

  16. The Facts … Spring ‘05 F includes people who forgot to withdraw and just stopped attending. 2049 Charge - Electric Field CH 23

  17. What I learned: • Students don’t like lectures, especially PowerPoint. • Students don’t like WebAssign • Some problems too hard • Some problems are not coded correctly by WA. • Students don’t like tests unless they are easy. • They’re NOT! • Course is hard, why would tests be easy??? 2049 Charge - Electric Field CH 23

  18. My gripes …. • Students study at the last minute. • Students have big holes in their math skills: • Interpreting Graphs. • Using Calculus. • Students come to my office expecting me to solve their homework problems. • I will always help … I will not give you the answers! • Work on the problems before you come for help. 2049 Charge - Electric Field CH 23

  19. How to get an A. STUDY ! 2049 Charge - Electric Field CH 23

  20. Let’s get started … • There is a WebAssignment on board. Be sure to register so you can get started. • Read the beginning of chapter 23. • Deals with charge, Coulomb’s Law and the Electric Field. • There will probably be a quiz on Friday. We’ll see on Wednesday. • I NEVER give POP quizzes. There will always be warnings. 2049 Charge - Electric Field CH 23

  21. Quizzes Usually one per week except when there is a holiday or a regular examination. Scored on a scale of 0-10. I will not count your lowest quiz grade. Quizzes are usually (but not always) repeats of homework problems or problems that I review in class. 2049 Charge - Electric Field CH 23

  22. Electricity 2049 Charge - Electric Field CH 23

  23. Don’t Mess With Mother NatureSt. Elmo’s Fire Top of Mast 2049 Charge - Electric Field CH 23

  24. A Quick Experiment 2049 Charge - Electric Field CH 23

  25. Idiot! If lightening had actually traveled down the kite string, old Ben Franklin would have been toast! 2049 Charge - Electric Field CH 23

  26. History • 600 BC • Thales of Miletos rubs amber (electron in Greek) with cat fur and uses it to pick up feathers. • Important questions: • Why was he doing this? • Didn’t he have a job?? • What happened to the skinned cat? 2049 Charge - Electric Field CH 23

  27. Amber Million years ago large stands of forests in some parts of the world began to seep globs of sticky resin! This aromatic resin oozed down the sides of trees, as well as filling internal fissures, trapping debris, such as seeds, leaves, feathers and insects. As geologic time progressed the forests were buried and the resin hardened into a soft, warm, golden gem, known as amber. Amber is the fossilized resin of ancient trees which forms through a natural polymerization of the original organic compounds. Most of the world's amber is in the range of 30-90 million years old. 2049 Charge - Electric Field CH 23

  28. Rubbings Demo .... 2049 Charge - Electric Field CH 23

  29. Brief Summary 2049 Charge - Electric Field CH 23

  30. Photo Volunteer Needed Must be Insured! 2049 Charge - Electric Field CH 23

  31. 2049 Charge - Electric Field CH 23

  32. What’s Going On? • All of these effects involve rubbing two surfaces together. • Or pulling two surfaces apart. • Something is on each of these objects. • We call this “something” CHARGE. 2049 Charge - Electric Field CH 23

  33. We have also observed that there must be TWO kinds of charge. • Call these two types • positive (+) • negative(-) • We “define” the charge that winds up on the rubber rod when rubbed by the dead cat to be NEGATIVE. • The charge on the glass rod or the dead cat is defined as POSITIVE. 2049 Charge - Electric Field CH 23

  34. What happens when two surfaces touch or rub? Bonding! 2049 Charge - Electric Field CH 23

  35. Example - Tape 2049 Charge - Electric Field CH 23

  36. The Balloon (Charged) Wall 2049 Charge - Electric Field CH 23

  37. 2049 Charge - Electric Field CH 23

  38. The Triboelectric Series When two of the following materials are rubbed together under ordinary circumstances, the top listed material becomes positively charged and the lower listed material becomes negatively charged.MORE POSITIVE rabbit's fur glass mica nylon wool cat's fur silk paper cotton wood acrylic cellophane tape polystyrene polyethylene rubber balloon saran wrap MORE NEGATIVE No! No! No! No! 2049 Charge - Electric Field CH 23

  39. What have we found? • There are TWO types of charge. • Positive • Negative • Like Charges Attract • Un-Like charges repel • The force between charges increases as they are brought closer together. • This charge separation results from chemical bonds which are severed in the process. 2049 Charge - Electric Field CH 23

  40. Forces Between Charges 2049 Charge - Electric Field CH 23

  41. Types of Materials • Insulators • Holds a charge • Conductors • Allows charge to easily move (current) • Semiconductors (Si, Ge, C …) • Somewhere in the middle, very temperature and impurity sensitive. • Used for transistors and optical devices such as LEDs and Semiconductor Lasers. • Semi-Metals • Don’t ask! 2049 Charge - Electric Field CH 23

  42. Charles Augustin de Coulomb (1736 - 1806) 2049 Charge - Electric Field CH 23

  43. Coulomb’s Law The Unit of Charge is called THE COULOMB Smallest Charge: e ( a positive number) 1.6 x 10-19 Coul. electron charge = -e Proton charge = +e 2049 Charge - Electric Field CH 23

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