Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions PHYSICS 272 Electric & Magnetic Interactions Section 1 MW 8:30-9:20AM Prof. Michael Manfra Room:84, Phone:43016 Section 2 MW 9:30-10:20AM Prof. Yong Chen  You Are in This Section The two sections cover the same material

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions Course Content This course deals with electric and magnetic interactions, which are central to the structure of matter, to chemical and biological phenomena, and to the design and operation of most modern technology [foundational to all engineering] The main goal of this course is to have you engage in a process central to science: the attempt to model a broad range of physical phenomena using a small set of powerful fundamental principles. The specific focus of the course is an introduction to field theory, in terms of the classical theory of electricity and magnetism (E&M). The course also emphasizes the atomic structure of matter, especially the role of electrons and protons in matter.

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions Schedule Lectures --- One of the follow sections (Sec. 1): Monday, Wednesday 8:30 - 9:20AM (50 minutes) –Lecture Room: PHYS 112 –Instructor: Prof. Michael Manfra –Office hours: by appointment –Office: PHYS 84, Phone: (49) – (please use subject: PHYS 272) (Sec. 2): Monday, Wednesday 8:30 - 9:20AM (50 minutes) –Lecture Room: PHYS 112 –Instructor: Prof. Yong Chen –Office hours: by appointment –Office: PHYS 74, Phone: (49) – (please use subject: PHYS 272) Teaching Assistants (Rec/Lab): Jonathan Nistor, David Blasing, Mike Fink, John Doyle, Mark Palenik, Zachary Wolff Course information: – –Undergraduate Office - PHYS 144

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions Textbook The textbook is Matter & Interactions, vol II: Electric & Magnetic Interactions by R. Chabay & B. Sherwood (John Wiley & Sons 2011). We will cover almost all of the topics in this volume. See the table of contents at the front of the book (which also includes the contents of Volume I). Make sure it is the Third Edition. The new book comes with a free coupon for WebAssign, the on-line homework service. Follow the instructions and get yourself registered.

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions General Information Room PHYS 144: Undergraduate office Room PHYS 12: Help center Room PHYS 290: Physics Library We will use WebAssign for homework and lab assignments. You will be able to access your scores in CHIP. See “Important Links” on course web page for details! For questions concerning WebAssign contact: V.K. Saxena: Office: PHYS 176, Phone:

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions Activities and Responsibilities In-class activities and responsibilities –You are responsible for attending all classes, and attendance will count toward your grade. –Bring the textbook and a scientific calculator to class. –If you miss class, it is your responsibility to find out what you missed. Lectures slides will be available shortly after lecture concludes. Recitations and Lab Sessions Homework –Homework and lab assignments will be posted on the web. See WebAssign (and Calendar section) for due dates. Outside class –Study assigned textbook sections. –An assignment to study sections of the textbook means: Read the assigned textbook sections thoughtfully (try “self-retrieving”). Do the "stop and think" activities. Write brief solutions to the in-line "exercises" and keep them in a notebook.

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions Quizzes, Exams, Grades Clicker Questions in Lecture: –Short multiple choice questions will be posed in lecture. The purpose is to assess your understanding. It will also be used to check attendance. We will start counting clicker questions towards your grade at lecture #5. –You have to purchase an iClicker ( ) from the bookstore. –You must register your clicker ID in CHIP!!!! Exams: –There will be two 1.5-hour exams and a 2-hour final exam. All exams are closed-book, but relevant formulas and constants will be provided. Grades: –The final grade will be determined on the following basis (Course Total = 700 points): 200 points - final exam 100 points each - two 1.5-hour exams (see calendar) 75 points - WebAssign homework 100 points – Labs 25 points - Clicker Questions & Attendance 50 points – Weekly Quizzes 50 points – Recitation Problems

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions This Week Study chapter 13 Lab will start this Wed, Thurs, Friday: Pre- Course Assessment Do Homework in WebAssign Announcement Lab Manuals no longer available in Union/BoilerCopyMaker Please print your copy BEFORE coming to Lab!

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions Clicker Question 1 My year in college is – A)Freshman B)Sophomore C)Junior D)Senior 

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions Clicker Question 2 My major is – A)Engineering B)Science C)Liberal Arts D)Education E)Other

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions Clicker Question 3 Are you majoring in any of the following – A)Electrical and Computer Engineering (ECE) B)Physics C)A and B D)Aether Studies E) Other

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions Electric and magnetic fields manifest their existence through interactions with matter Electric and Magnetic Fields Maxwell equations: Lorentz force:  curl(E)  E   B  t

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions Two types: positive and negative Like charges: repel Opposite charges: attract Charge is quantized in units of e Millikan’s oil drop experiment ( ) “Fractional” quantized charge (quarks, FQHE…) [not in everyday life] Point charge: Size is small compared to the distance between it and other objects of interest Electric charge is an intrinsic property of the fundamental particles that everything is made of Universe’s Net charge is conserved Point Charges

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions Q1Q1 Q2Q2 F F "The magnitude of the electrostatic force between two point charges is directly proportional to the magnitudes of each charge and inversely proportional to the square of the distance between the charges." The Coulomb Force Law Charles-Augustin de Coulomb ( )

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions The Coulomb Force Law  0 = permittivity constant of vacuum (air is close) Force repulsive r F 21 Force attractive r F 21 1 The force exerted by one point charge on another acts along line joining the charges. The force is repulsive if the charges have the same sign and attractive if the charges have opposite signs. Force on “2” by “1”

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions Units and Constants SI units of electric charge : Coulomb, C Constants : 1/4  0 = 9x10 9 N. m 2 /C 2  0 = 8.85x C 2 /N. m 2 permittivity constant of vacuum e = 1.602x C (“unit charge’) 1 C = 6.24x10 18 elementary charges ParticleCharge electron-e positron+e proton+e antiproton-e neutron0 photon 0 up quark +(2/3)e down quark -(1/3)e

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions Structure of Atom Nucleus: ~10 4 times smaller than electron cloud, ~10 4 times heavier than electron. Matter consists of atoms 1 cm 3 : ~10 24 atoms Example: nucleus of the iron atom Size: ~10 –15 m, mass: ~ kg 1Å=0.1nm= m Nucleus charge = +Ze, atom with Z electrons is neutral.

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions The Concept of Electric Field Accelerates at 9.8 m/s 2 – why? Accelerates at m/s 2 – why? There are many possible configurations of charges to produce the observed effect.

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions There is something in space waiting for a charged particle to interact with it! This virtual force is called electric field. An electric field created by charge is present throughout space at all times, whether or not there is another charge around to feel its effect. Electric Field

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions Definition of Electric Field

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions If our probe charge is positive or negative F due to given E will point in correct direction. [N/C] Electric Field Electric field has units of Newtons per Coulomb:

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions Including direction: The Electric Field of a Point Charge + -

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions A particle with charge +2 nC (1 nanoCoulomb=10 -9 C) is located at the origin. What is the electric field due to this particle at a location m? Example Problem Solution: 1.Distance and direction:  r  observed_location  source_location

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions 2. The magnitude of the electric field: 3. The electric field in vector form: Example Problem

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions The Physical Concept of ‘Field’ Field: physical quantity, can be scalar or vector Examples: Temperature T(x,y,z,t) --- scale Air flow, gravitational field --- vector m q

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions Example: The electric field at a particular location is N/C. What force would an electron experience if it were placed in this location? e Solution: E F Forces due to an Electric Field Y X

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions Re-Cap (EMI ) Course elements: lecture, recitation, lab, WebAssign… Coulomb’s law for electric force Point charges and unit of charge Electric force  electric field Next time (EMI ) Superposition of Electric field due to multiple charges Electric dipole

Fall 2010 Prof. Yong Chen Prof. Michael Manfra Lecture 1 Slide PHYS 272: Matter and Interactions II -- Electric And Magnetic Interactions Food for Thought: “Coulomb” Blockade Small transistors: Single electron charge matters! To read more: Marc Kastner: “Artificial Atoms”, Physics Today, Jan. 1993, pp24 “Coulomb blockade lab”: Moore’s law