PHYS 100C 2009

Revision as of 11:09, 30 April 2009

Welcome to Physics 100C webpage.

RECENT UPDATES:

in reverse chronological order

• April 30: Lecture 10 (PDF) Summary: we derived the radiated E, B fields for oscillating dipole, using retarded potential formalism (11.1.1, 11.1.2 in the textbook). Result is spherical EM wave (transverse), intensity ~ fourth power of frequency (Rayleigh scattering and the reason for why the sky is blue), decays as inverse square of distance, has cos²(theta) angular anisotropy with respect to dipole orientation.
• April 28: I will be holding additional office hour, Wednesday, April 29th, at 3PM (Mayer Hall Addition 3681), for students who would like to discuss homework, lectures or complain about horrible Lienard-Wichert potentials. I should also be in my office from 11AM to noon tomorrow (Wed. Apr. 29) for those who have conflict with PHYS 120A, but would like to talk to me.
• April 28: Homework #3 Solutions (PDF) posted.
• April 28: Lecture 9 (PDF) Summary: Lienard-Wiechert potentials for moving charge, expanded. Velocity and acceleration contributions to E derived.
• April 26: Midterm tentatively (re)scheduled for Thursday, May 14th, in class (8AM-9AM).
• April 23: HW #4 posted: 10.1, 10.3, 10.5, 10.7, 10.10 (finalized), Due Thur, Apr. 30, 8AM.

OLDER UPDATES:

• April 23: Lecture 8 (PDF) Summary: derived Jefimenko Eqs (fields from retarded potentials) 10.2.2. Derived general expression for Lienard-Wichert potentials for moving charges. (10.3.1)
• April 21: For those interested in deep discussions (obviously not required for this course!) on nature and direction of arrow of time see here, here, here, or here, or google "Boltzmann's Brain", "Arrow of time" or "Gibbs paradox".
• April 21: Lecture 7 (PDF) Summary: we introduced gauge transformations (10.1.2), Coulomb and Lorentz gauges, and Maxwell equations in these gauges (10.1.3). Introduced "retarded" potentials in Lorentz gauge and demonstrated that they are a solution to Maxwell equations for potential V(r,t) (10.2.1).
• April 21: Homework #2 Solutions posted.
• April 17: In Homework #3, Problem 9.28, the frequency 1.7E10 Hz is not the angular frequency, omega, but rather the inverse of period, "regular" frequency, usually described by greek letter nu. In Problem 9.30 you may assume that a > b (rectangular dimensions of waveguide).
• April 16: Lecture 6 (PDF) summary: continued description of waveguides, applied to specific example of rectangular waveguides (9.5.2). Treatment of coaxial transmission line (9.5.3) is left to class. Started discussion of potentials and fields in electrodynamics, gauge transformations (10.1.1 and 10.1.2).
• April 16: Homework #3 posted: 9.23, 9.24, 9.27, 9.28, 9.30. In Prob. 9.23 ignore the last question, answer only the first two - see PDF.
• April 14: Votes are in! We will keep having discussion session at original timeslot, 11-11:50 on Fridays.
• April 14: Homework #1 Solutions are posted.
• April 14: Group velocity animations - see applets here and here, and also wikipedia page with relevant references about slowing down light to bike/running velocities and "negative" speed of light.
• April 14: for any questions/conflicts about homework grading first contact the grader (Houdong Hu, hhu@physics.ucsd.edu), then email/talk to me.

Homework #2, extra credit problem: derive the most *general* solution of equation Ax"+Bx'+Cx=D*cos(wt) by solving homogeneous form of this 2nd order differential equation (D=0 - undriven/damped harmonic oscillator) first, and then finding general form of x(t) for when driving force parameter D is not equal to 0. (The question/objections raised by Jeff and Andrew in class.) Separate transient part due to some initial conditions (at short t as compared to the damping time constant) from solution describing long-term, steady-state behavior we are interested in (large t). Compare this long-term behavior to the solution introduced in class. This extra credit for mathematically motivated students is due Thursday 8AM - I will post/discuss solution on Friday during our Discussion Session.

• April 14: Lecture 5 (PDF) summary: We derived dispersion relation for a simplistic "mass on a spring" model for electron in EM waves (Section 9.4.3). We also started deriving Maxwell equations for EM waves in waveguide (conducting tube). (Section 9.5.1)
• April 13: Homework #2 Hints - in Prob. 9.16 you may assume that both reflected and transmitted waves are also s-polarized (we did Prob. 9.14 that deals with this proof during Discussion session on Friday). You may also want to do Prob. 9.19 before proceeding to 9.21 (silver is a very good conductor).
• April 10: Q&A Notes (PDF) (mostly some answers to questions Jeff keeps asking me during the lectures - not required reading material by any means, for general education only).
• April 9: Lecture 4 (PDF) summary: We derived equations for EM waves in conducting media. The solutions for wavevector now have imaginary component, which means the wave amplitudes are exponentially decaying over "skin depth" near the surface. E and B are still mutually perpendicular, but are out of phase. (9.4.1)

We also derived equations for transmitted and reflected waves for EM wave normally incident at an insulator-conductor interface. Perfect conductor has 100% reflection coefficient. (9.4.2).

• April 7: Lecture 3 (PDF) summary: We derived equations for transmitted and reflected EM waves for a case of normal incidence (cont'd from Lecture 2), See section 9.3.2. We then derived a more general case of oblique incidence, p-polarized wave; Discussed Brewster angle and applications (polarized glasses and Brewster Angle Microscopy). Section 9.3.3.

Reminder that HW#1 is due Thur April 9 at the beginning of the lecture, 8AM.

• April 4: Feel free to add feedback, comments or suggestions regarding the PHYS 100C course in the discussion section (anonymously or not). Please do not edit this (main) page.
• April 2: Problems 9.3, 9.5, 9.9 (sketch optional), 9.10, 9.15 (note that 9.13 will be deferred for HW #2) will be due as HW #1 next Thursday, Apr. 9 before lecture.
• April 2: Lecture 2 (PDF) summary: we have derived energy density, energy flux, momentum density and radiation pressure of EM waves (9.2.3), propagation of EM waves in Linear Media (9.3.1), defined boundary conditions for EM wave traveling across media boundary and formulated the Incident, Transmitted and Reflected waves (9.3.2).
• April 1: Lecture 1 (March 31) summary: we covered waves in 1D (9.1.1-9.1.2), discussed transverse/longitudinal waves (9.1.4), derived EM waves in vacuum from Maxwell Eqs. (9.2.1, 9.2.2).
• March 31: Change in policy - during the discussion session we will be breaking into small groups and solving problems, including (sometimes) upcoming homework problems. Therefore, student collaborations on homeworks is now allowed. Participation in discussion sessions is optional.
• March 31: Lecture 1 Notes posted.
• March 31: Discussion session: Fridays 11:00-11:50, WLH 2110.
• March 31: RSS and Atom feeds allowing you to subscribe to/monitor changes to this page are available from this webpage (links in lower left panel)
• March 25: Syllabus has been posted.

COURSE SUMMARY:

PHYS 100C, Electromagnetism, Spring 2009, UC San Diego

Professor: Oleg Shpyrko, oleg@physics.ucsd.edu

Office: Mayer Hall Addition (MHA) 3681, ext. 4-3066 (Where is it?)

Office Hours: Combined with Discussion Session, and on Mondays 3PM-4PM. For additional time see me after lectures or on demand.

TA (Grader): Houdong Hu, hhu@physics.ucsd.edu

Text: Introduction to Electrodynamics, 3rd Edition, by David J. Griffiths.

Lectures: Tue, Th 8:00am-9:20am, HSS 2154

Discussion Session: Fridays 11-11:50,WLH 2110.

Homework: Assigned weekly, due Thursday, at the START of lecture. Will also be accepted at the following lecture, but with a 20% penalty.

Midterm: Tue, May 14th 8:00AM – 9:20AM, HSS 2154 (in class). Open book exam. Bring your textbook only, and a bluebook.

Final: June 11, 8:00AM – 11:00AM. Open book exam. Bring your textbook only, and a bluebook.

Grading: Homework=20%, Midterm =30%, Final=50%.

Academic Dishonesty: Please read the section entitled "UCSD Policy on Integrity of Scholarship" located in the2008-2009 General Catalog, www.ucsd.edu/catalog (More specifically, see page 69 of PDF document) The rules on academic dishonesty will be strictly enforced!

Course Webpage: x-ray.ucsd.edu/PHYS_100C (RSS/Atom feeds available) ---

COURSE SCHEDULE: