PHYSICS 7 Electic & Magnetic Inteactions Pof. Andew Hisch Hisch@pudue.edu Room: 78, Phone: 48
Couse Content This couse deals with electic and magnetic inteactions, which ae cental to the stuctue of matte, to chemical and biological phenomena, and to the design and opeation of most moden technology. The main goal of this couse is to have you engage in a pocess cental to science: the attempt to model a boad ange of physical phenomena using a small set of poweful fundamental pinciples. The specific focus of the couse is an intoduction to field theoy, in tems of the classical theoy of electicity and magnetism (E&M). The couse also emphasizes the atomic stuctue of matte, especially the ole of electons and potons in matte.
Schedule Lectues: Tuesday, Thusday :30 - :0 Lectue Room: PHYS Instucto: Pof. Andew Hisch Office hous: by appointment Office: PHYS 78, Phone: (49)-48 Email: hisch@pudue.edu (please use subject: PHYS 7) Teaching Assistants: Chistos Deligkais, Jonathan Nisto, Mak Palenik, Justin Sheek, Zachay Wolff, John Yeazell Couse infomation: http://www.physics.pudue.edu/academic_pogams/couses/phys7/ Undegaduate Office - PHYS 44
Textbook The textbook is Matte & Inteactions, vol II: Electic & Magnetic Inteactions by R. Chabay & B. Shewood (John Wiley & Sons 007). We will cove almost all of the topics in this volume. See the table of contents at the font of the book (which also includes the contents of Volume I). Make sue it is the Second Edition. The new book comes with a fee coupon fo WebAssign, the on-line homewok sevice. Follow the instuctions and get youself egisteed.
Geneal Infomation Room PHYS 44: Undegaduate office Room PHYS : Help cente Room PHYS 90: Physics Libay We will use WebAssign fo homewok and lab assignments. You will be able to access you scoes in CHIP. See Impotant Links on couse web page fo details! Fo questions concening WebAssign contact: V.K. Saxena: Office: PHYS 76, Phone: 49575
Activities and Responsibilities In-class activities and esponsibilities You ae esponsible fo attending all classes, and attendance will count towad you gade. Bing the textbook and a scientific calculato to class. If you miss class, it is you esponsibility to find out what you missed. Lectues slides will be available shotly afte lectue concludes. Homewok Homewok and lab assignments will be posted on the web. See WebAssign (and Calenda section) fo due dates. Outside class Study assigned textbook sections. An assignment to study sections of the textbook means: Read the assigned textbook sections thoughtfully. Do the "stop and think" activities. Wite bief solutions to the in-line "execises" and keep them in a notebook.
Quizzes, Exams, Gades Clicke Questions in Lectue: Shot multiple choice questions will be posed in lectue. The pupose is to assess you undestanding. It will also be used to check attendance. We will stat counting clicke questions towads you gade at lectue #5. You have to puchase an iclicke ( http://www.iclicke.com ) fom the bookstoe. You must egiste you clicke ID in CHIP!!!! Exams: Thee will be two -hou exams and a -hou final exam. All exams ae closed-book, but elevant fomulas and constants will be povided. Gades: The final gade will be detemined on the following basis (Couse Total = 700 points): 00 points - final exam 00 points each - two -hou exams (see calenda) 75 points - WebAssign homewok 00 points Labs 5 points - Clicke Questions & Attendance 50 points Weekly Quizzes 50 points Recitation Poblems
Announcement To help us assess how well you lean this mateial, and how well we ae teaching it, you will be given a concise multiple-choice test of you undestanding of basic electical and magnetic physics duing the fist lab session (Aug. 6, 7, 8) and duing you last lab session (Dec. 9, 0, ) scheduled. At the end of the semeste we will give you you scoes on both tests. By compaing them you, and we, will be able to see how much you have leaned about electicity and magnetism fom this couse. It is impotant that you attend both you fist and last lab sessions to take these tests. If you complete BOTH test, you will eceive an additional 0 points. These will be added to you point total afte gade cut offs have been set!
This Week Study chaptes 3 and 4 (4.) Lab will stat this Wed, Thus, Fiday: Pe-Couse Assessment
Clicke Question A) Engineeing B) Science C) Libeal Ats D) Education E) Othe My majo is
Clicke Question A) Physics B) Physics C) Physics D) Physics Ε) Πηψσιχσ My favoite subject is
Electic and Magnetic Fields Electic and magnetic fields manifest thei existence though inteactions with matte Maxwell equations: ρ div( E) = E = ε0 div( B) = B = 0 cul( E) = E = B t cul( B) = B = µ 0 J + ε 0 E t Loentz foce: F = qe + qv B
Point Chages Two types: positive and negative Like chages: epel Opposite chages: attact Chage is quantized in units of e Millikan s oil dop expeiment (90-93) Point chage: Size is small compaed to the distance between it and othe objects of inteest Electic chage is an intinsic popety of the fundamental paticles that eveything is made of
F = The Coulomb Foce Law F = 4πε 0 Q Q "The magnitude of the electostatic foce between two point chages is diectly popotional to the magnitudes of each chage and invesely popotional to the squae of the distance between the chages." Q Q Chales-Augustin de Coulomb (736-806) F F
F = The Coulomb Foce Law 4πε 0 Q Q ˆ ε 0 = pemittivity constant + + Foce epulsive F Foce on by + F - Foce attactive The foce exeted by one point chage on anothe acts along line joining the chages. The foce is epulsive if the chages have the same sign and attactive if the chages have opposite signs.
Units and Constants SI units of electic chage: Coulomb, C Constants: F = F /4πε 0 = 9x0 9 N. m /C ε 0 = 8.85x0 - C /N. m pemittivity constant e =.60x0-9 C C = 6.4x0 8 elementay chages Paticle Chage electon -e positon +e poton +e antipoton -e muon +e o e pion +e o e o 0 neuton 0 = 4πε 0 Q Q
Matte consists of atoms cm 3 : ~0 4 atoms Stuctue of Atom Nucleus: ~0 4 times smalle than electon cloud, ~0 4 times heavie than electon. Å=0-0 m Example: nucleus of the ion atom Size: ~0 5 m, mass: ~0-5 kg Nucleus chage = +Ze, atom with Z electons is neutal.
The Concept of Electic Field Acceleates at 9.8 m/s why? Acceleates at 0 m/s why? Thee ae many possible configuations of chages to poduce the obseved effect.
Electic Field Thee is something in space waiting fo a chaged paticle to inteact with it! This vitual foce is called electic field. An electic field ceated by chage is pesent thoughout space at all times, whethe o not thee is anothe chage aound to feel its effect.
Definition of Electic Field E q F = = = 0 0 4 4 q q F q q F πε πε / q F E =
Electic Field E = F / q If ou pobe chage is positive o negative F due to given E will point in coect diection. E E,,, ( x y z t) Electic field has units of Newtons pe Coulomb: [N/C]
= 0 4 q q F πε E q F = 0 4 q E πε = q E ˆ 4 0 πε = Including diection: The Electic Field of a Point Chage + -
Example Poblem A paticle with chage + nc ( nanocoulomb=0-9 C) is located at the oigin. What is the electic field due to this paticle at a location <-0.,-0.,-0.> m? Solution:. Distance and diection: = obseved _ location souce_ location = 0., 0., 0. 0, 0, 0 = 0., 0., 0. = 0. ˆ = ( ) + ( 0.) + ( 0.) = 0.35 m = 0., 0., 0. 0.35 E = 0.57, 0.57, 0.57 = 4πε 0 q ˆ
Example Poblem. The magnitude of the electic field: E q Nm C 9 0 C 0.35 m = 9 9 0 = 4πε0 E = 47 N C = 4πε 0 q ˆ 3. The electic field in vecto fom: E E = = Eˆ N = 47 C 84, 84, 84 0.57, 0.57, 0.57 N C
The Physical Concept of Field Field: physical quantity, can be scala o vecto Examples: Tempeatue T(x,y,z,t) Ai flow, gavitational field m F = F = mg qe q
Foces due to an Electic Field Example: The electic field at a paticula location is <-300,0,0> N/C. What foce would an electon expeience if it wee placed in this location? Y E e F X Solution: F = ee =.6 0 9 C 300,0,0 N/C F = 4.8 0 7,0,0 N