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PHY 2049 Spring 2005. Dr. Jeff Bindell. On the WebSite www.physics.ucf.edu/~bindell. Copies of many of the overheads that will be used in class. (Today’s Included) Click on: PHY 2049 Lecture Section Copies of any PowerPoint presentations used in the class.
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PHY 2049Spring 2005 Dr. Jeff Bindell
On the WebSitewww.physics.ucf.edu/~bindell • Copies of many of the overheads that will be used in class. (Today’s Included) • Click on: PHY 2049 Lecture Section • Copies of any PowerPoint presentations used in the class. • The syllabus (watch it for any changes) • Helpful hints • Unhelpful hints
We will begin using WebAssign THIS WEEK, so do not delay registering. WebAssign HWs may NOT be always announced in class so please check the site every day or two.
WebAssign • Homework Assignments • Communications Page • e-mail to instructor • requests for extensions • I am easy with these but you must include a reason. • requests for assistance • I don’t always respond to these. • Forums • Announcements about tests, quizzes, changes, etc. • NOTE – There is already an assignment posted. An “Intro to Using WebAssign”
Quizzes • Expect a quiz every week. • Usually on Friday. • Quiz will be either • 1 problem similar to the WebAssign problems, • A few multiple choice questions. • I do not use “pop” quizzes. • RateMyProfessors says that my tests are hard. • It also says some other nasty things!
MAKE-UP EXAMS Make-up quizzes and examinations will not be allowed unless there is a very compelling personal reason for doing so. Included among excused absences are death (yours, a family member or close friend), illness in the family, family emergencies and excused absence due to participation in sporting events or other sanctioned UCF activities Initial requests must be in writing or email.
About the course • PHYSICS FOR ENGINEERS AND SCIENTISTS II IS HARD!! • Everything builds on previous material. • If you wait until exams to study you are doomed. • Keep up with your homeworks and reading assignments. • Study a lot! • Ask for help if you need it.
Course Overview • Electricity • Charges • Moving Charges (currents) • Forces on charges • Potential (an energy concept) • Types of materials • Electrical Elements & Circuits • Some additional topics that will drive you crazy. Laterally!
More Course • Magnetism • Magnets • Magnetic Fields • Forces on charges in magnetic fields • Creating Magnetic Fields • Induction & Inductance • AC Circuits • Additional • Optics • diffraction • interference
The “Flow” Mechanics Electricity Magnetism Induction Maxwell OPTICS
DEMO NOTICE This stuff doesn't always work!
Let’s try it • Rod/Cloth Experiments • Conclusions • Van der Graaf Demo • What’s going on here?
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.
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.
Idiot! If lightening had actually traveled down the kite string, old Ben Franklin would have been toast!
Don’t Mess With Mother NatureSt. Elmo’s Fire Top of Mast
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?
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.
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! The Triboelectric Series
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 severe in the pocess.
