Physics 220 Fall David Allred is instructor My Goal is your learning. Chapter 23 1
Today: An Introduction and Chapter 1 • The forces found in the universe: How many are there? • The beginning of our Mastery of One (or is it Two?) of them. • Some orientating demos in ELECTROSTATICS • Syllabus with calendar (get one) • Some information that should help you succeed • Course organization • Sources of help • An introduction to me (next time) more • A scripture story • & Getting Started in 220: things to do for Wednesday.
What are the forces of nature?
Learning objective for this class: After taking this course, students will be able to: 1. Use Maxwell’s equations to find electric and magnetic fields in a few highly-symmetric arrangements of charges and currents. Also find electric and magnetic fields by integrating over charge and current densities. 2. Solve problems and answer conceptual questions involving the motion of charged particles and the behavior of dipoles in electric and magnetic fields. 3. Analyze simple direct current and alternating current circuits. 4. Use basic electromagnetic theory to arrive at conclusions about practical devices including motors, generators, and particle accelerators. 5. Use Maxwell’s equations to solve problems and answer conceptual questions concerning electromagnetic radiation.
Demos: to illustrate where we are going this semester. • AC ring toss. (Chapter 31 Faraday’s law) • E&M waves (Chapter 34 • Charged particles moving in magnetic field – Chapter 29 & 30 • Charged objects: Forces from them – Chapters 23 and 24
Maxwell’s Eqns. are Beautiful
What you need to know about electrostatics • Basic facts: Force Law, definitions: • Three ways of charging an object (next time) & Conservation of charge. • Which charge goes with “Cat” fur and Amber (or rubber)? – Which goes on a glass rod? • Force Law with complications – In 2-D and 3-D and – between nonspherically charged objects. • You will see this slide again.
Concepts & Definitions • Negative is charge on Amber (or rubber) get. Amber = Elektra in Greek. • Charge conservation. • Charging by transfer, polarization or induction. • Conductors. Metals are example. • Insulators =nonconductors= dielectrics.
Electric Charge • Like charges repel. • Unlike charges attract. • F= k q 1 *q 2 / r 2 One-dimension
How to make an electric dipole using electrostatic induction.
Some Video demos: Qualitative Physics Notice: • Demo 17-1 shows making dipole. • Charged rods attracting and repelling. • The attraction of charged rods to the item that makes them charged. • Metals are attracted to either + or – charged rods. Why? • Electrophoris: Charging by electrostatic induction. (You don’t have to know about the electrophoris.)
Clicker quiz: If I double the distance between two point charges, the force: A. Quadruples B. Doubles C. Stays the same D. Is half as strong E. Is one quarter as strong If you did not bring a clicker & want points, do this 60-sec writing. What question about class do you have?
Physics 220 Fall Course Assignment Schedule
This is from the Packet. First homework assignment . Due in 4 days You will see this slide again next time. Student ID 000 Homework data Physics 220, Winter Semester 2007 set 1. [01] 0.726 [02] -2.91 [03] 4.21 [04] 1.94 [05] 4.11 set 2. [01] 2.15 [02] 4.47 [03] -2.38 set 3. [01] 722. [02] 30.4 [03] 6.47 [04] -5.34 set 4. [01] 5.96 [02] 7.93E+06 set 5. [01] 3.38 [02] -1.81 [03] 3.90 [04] 5.05
Parable of lost sheep • He told them this parable. "Which of you men, if you had one hundred sheep, and lost one of them, wouldn't leave the ninety-nine in the wilderness, and go after the one that was lost, until he found it? When he has found it, he carries it on his shoulders, rejoicing. When he comes home, he calls together his friends and his neighbors, saying to them, 'Rejoice with me, for I have found my sheep which was lost!' I tell you that even so there will be more joy in heaven over one sinner who repents, than over ninety-nine righteous people who need no repentance." • — Luke 15:3-7, World English Bible
David Allred (more next time.) • A few relevant characteristics – I fidget and – I sometimes say things exactly wrong. I know the right answer but as I say it, I give the answer exactly backwards. • I need someone to correct me when I do. – I (try to) use humor in teaching – I want to help you master this subject. • Office: N265 Eyring Science Center (ESC) • Office hours: MWF 10:10 – 11:00 AM & By appointment • Email: allred@byu.edu or dda@byu.edu • Office phone: 422-3489 Cell: 400-8277 Home: 225-4967 • What to call me (Prof., Dr., Mr., Bro., Granpa…)
For next time: (& I will emailed this to you.) • Do the following: – Read the Syllabus - the whole thing. Clicker quiz on first page and HW section. – Look at homework assignment #1. • Do and turn it in online by Friday. – Read Preface xvii through xxiv and 23.1 through 23.5 in preparation for the next class. – Buy clicker & bring it to class on Wednesday. – Get a copy of the text and the “Physics 220 Packet” from the Bookstore . – A few copies are in the TA lab N361 ESC.
Physics 220 Getting Started • Get a copy of the text and the “Physics 220 Packet” from the Bookstore . • A few copies of the text (QC 23 .s458 1996 ol. 2) are available in the reserve library and scattered throughout the complex of Physics Tutorial labs (N304). • Get your class ID number (CID) and write it on your ‘chapter Summaries” • Locate the following: – The classroom: 445MARB. – The display cases: in the hallway near N361 ESC, where solutions to homework and exams are posted. – The Walk-in lab: S415 ESC. – The distribution center in the hall just outside N375 ESC. Notice the ‘220 Homework’ slots near the left-hand end near the floor; this is where you submit homework. You get it back in one of the 100 slots to the right. There are also slots for late homework and appeals. • The Physics 106/220 Tutorial Lab: N304 ESC. – The reserve library - (now located near the circulation desk) if you intend to use any of the materials we have placed on reserve.
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