Homework: I'll assign weekly problem sets, due Tuesdays @ 11:59 pm. You may leave your homework in my mailbox near the physics department office, or of course you may give it to me personally (please do NOT leave it in the box beside my office or stick it under my door). Homework submitted late without prior arrangement will receive a 50% penalty if submitted within three days of the due date (i.e. by Friday @ 11:59 pm), and will not be accepted for a grade after that.
Why do the homework?
I can't emphasize enough the importance of working the problems.
In some of your
classes homework is primarily evaluative; the point is for you to
demonstrate what you've learned from the readings and lectures. In physics
the homeworks are primarily instructional;
you learn physics primarily by doing working problems.
You must work the
problems, think about the results, and understand any mistakes you've
made if you wish to attain the type of understanding of the subject
required of a working physicist. In at nutshell:
If you can't work problems you don't know physics.
I (or a grader) will grade the problems,
and I'll hand out solutions. I encourage
you to read the solutions and understand any mistakes immediately.
If it doesn't
make sense, ask me about it right away---don't wait
until right before an exam.
Extensions
If you've got a compelling reason why you need an extension,
come talk to me in advance.
I will not grant a homework extension without penalty if you ask for
it on the day the homework is due, so don't ask for one.
[If you need such a last-minute or post-facto extension due
to extenuating circumstances (e.g. death in the family, sudden
illness, travel problem), you'll need to have the Dean of Students
or your Class Dean formally make such a request to me and suggest
a rescheduled due date. You should also take this route if you
need an extension but you don't want to tell me why (say, it's for
personal or legal reasons). If you explain your reason to a Dean
and the Dean tells me it's OK, that's good enough for me.]
In general, though,
life will be easier for you and for me if you get into the habit
of doing your best to finish the problem set on time and handing
in as much as you've been able to complete by the deadline.
The College requires that all written work for a course except for a final be submitted by 5 pm on the last day of classes. The physics department takes this deadline seriously. After that day/time no homework will be accepted.
The roles of lectures and textbooks
Lecture will not be a regurgitation of the text, a summary of all
you need to know for the course, or a how-to guide for the homework.
Rather, I'll try go deeper into selected points.
In lecture I'll cover material and do demonstrations
related to the readings, but I won't feel obliged to
be comprehensive in those places where I feel the text is adequate
and I may focus only on a few points that I feel are particularly
interesting or subtle. You shouldn't expect to understand what's
going on without close study of the readings, and you
should come to class with questions you have
on the readings. Further, after we settle into the semester
a bit, I expect the classes will become less lecture-oriented
and more participatory; it will be difficult to reap
the maximum benefit from that format if you're not
sufficiently prepared to fully participate.
For the problems you can't solve, talk to classmates, attend the problem sessions, or ask me. When you ask me, either try to give you just enough of a hint to get you through, or I'll guide you through the problem with a series of leading questions. I'll never just tell you how to do it. If you run out of time and don't finish the set, start earlier next week. When the solutions come out, look over them right away, before you've forgotten all of the points you were confused about. You think you'll just get clear on it before the next exam, but there's never as much time as you think.
On the other hand, if you find the class too slow for your liking, if you have questions that you aren't getting answers to, if you'd like more detail, if you are frustrated that we aren't digging deeply enough, if you crave more applications, come talk to me. I'm very happy to provide you with additional materials or explanations that will will stimulate you and challenge you at whatever level you can handle.
One word of warning: Amherst College students tend to have lots of extracurriculars of all types. I support this (enthusiastically), and I am occasionally willing to be flexible to facilitate your participation in range of activities, but don't let your extracurriculars overshadow your academics. If you become concerned that your courses are getting in the way of your extracurriculars, you definitely have the wrong mindset. Remember why you're here.
If circumstances in your life beyond the class are the problem, you can come talk to me, but also talk to your class Dean.
Key derivations / chains of logic / results to commit to memory
Mathematica Tutorials
We will use Mathematica 5.2 at least occasionally in the homework,
to obtain numerical solutions to problems that are not
analytically solvable and to simplify plotting of results.
If you've never used Mathematica before, or haven't used it much,
the tutorials will help you get started.
They were written by Professor Hilborn and revised by
Rebecca Erwin '02. If you download the file and save it to the
desktop with a .nb suffix in the name, your computer will recognize it
as a Mathematica notebook and will start up Mathematica automatically
when you double-click on the icon,
provided you have Mathematica installed. Mathematica is installed on
lots of the college's public machines, including
on the computers in the Physics
Department computer lab. Alternately, you can pay the $140 or so
to buy the student version.
Week | Lectures | Hmwk | Comments |
1. September 4 | Preliminaries: vectors and vector analysis Sept 5: Vectors and vector algebra Logistics of the course. Geometric and algebraic representations of vectors. Vectors in terms of components and basis vectors. Einstein summation convention. Abstract properties of vector spaces and vector operations. Vector products: scalar product, cross product. Kronecker delta, Levi-Civita symbol. Sept 7: Vector analysis [special guest lecturer: Prof. Jagannathan] Vectors: transformations under rotations active vs. passive transformations. rotations in matrix notation. properties of rotation matrices. rotations preserve lengths of vectors. group properties of rotations. scalars are invariant under rotation. Vector calculus gradient of a scalar field is a vector (transforms properly under rotations). Line integrals. fundamental theorem for gradients. divergence of a vector field is a scalar. flux of a vector field through a surface. fundamental theorem for divergences (gauss's theorem). curl of a vector field. expression in cartesian coordinates. Levi-civita symbol. curl of a vector field is a vector field. curl of gradient is zero. divergence of curl is zero. irrotational vector fields can be expressed as gradient of a scalar field. divergenceless vector fields can be written as a curl of a vector field. |
Read: Griffiths E&M: Chap. 1 Problems (PS1): Griffiths E&M: 1.6, 1.13, 1.14, 1.17, 1.60, 1.61, 1.62 [Due Tuesday Sept. 12, 11:59 pm] |
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2. September 11 | vector analysis Sept 12: more on vectors and vector analysis parity transformation euler's thm: right-handed coord systems related by rotation, related to left-handed by rotation + inversion. inversion transformation defined. vectors defined to behave like displacements. momentum is a vector. angular momentum is a pseudovector. electric fields are vectors, magnetic fields are scalars, E.B (a triple product) is pseudoscalar. del operator recap of geometrical definitions of div, grad and curl. expressions in expressions in cartesian coordinates. [warning: expressions in curvilinear coordinates generally not simple/obvious]. fundamental theorems for each operator. second derivatives formed using del operator. Sept 14: vector operators in curvilinear coordinates general orthogonal curvilinear coord. systems (u,v,w). coordinate singularity. def. of an orthogonal/orthonormal coord sys., unit vectors in these coord sys. scale factors and the line element. gradient in curvilinear coords. divergence in curviliear coords. special case: spherical coords. introduction to the dirac delta function: zero everywhere except at a single point, integrates to something nonzero and finite. example: mass density of a point mass (integrates to total mass of particle) |
Read: Griffiths E&M: Chaps 1 and 2, Appendices A and B Problems (PS2): Griffiths E&M: 1.47, 1.50, 1.51, 1.59, 2.6, 2.7, 2.43 [Due: Tuesday Sept. 19, 11:59 pm ] |
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3. September 18 | Electrostatics Sept. 19 : More math / Coulomb's law dirac delta function density of point charge/mass motivates definition of dirac delta fn in physics, but mathematically fraught. can view as limit of functions growing increasingly narrow and high, but with constant area. mathematically, view as linear functional that returns value of function at a point. rules for delta fns with functions as arguments. 3d delta fn. 3d delta fn as divergence of inverse square field. helmholtz decomposition theorem div, curl and boundary conditions at infinity are enough to uniquely specify a vector field. irrotational fields have zero curl. four equivalent conditions: curl F=0, path independence of line integral, line integral about closed loops vanish, F is gradient of scalar. solenoidal fields have zero divergence. four equivalent conditions: div F=0, flux through open surface with fixed boundary independent of the surface, flux through closed surface is zero, F is curl of a vector. electrostatics: coulomb's law statement of coulomb force law. obeys strong form of Newton's third law, implying conservation of linear and angular momentum momentum (although that's not static). electrostatic force obeys principle of linear superposition. electric charge is locally conserved (we'll see this follows from maxwell eqns). electric charge is quantized (we don't know why). Sept. 21: Electrostatic fields and Gauss's law [before lecture, skim the rest of chap. 2] Electrostatic field from Coulomb's law and principle of superposition. E-field of physical dipole: on-axis, then off-axis, expanded to 1st order in the d/r << 1 (long-distance) limit. Field lines and the field line picture as a motivation for Gauss's law. Start proof of Gauss's law: (1) for a point particle with spherical gaussian surface, (2) for a point particle with a general surface. Start an aside on solid angle. |
Read: Griffiths E&M: finish Chap 2, start Chap. 3 Problems (PS3): Griffiths E&M: 2.14, 2.16, 2.26, 2.31, 2.32, 2.48, 2.49 [Due Tuesday September 26, 11:59 pm] |
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4. September 25 | Chap. 3 Sept 26: title summary Sept. 28: title summary |
Read: Griffiths E&M: Chapter 3 Problems (PS4): Griffiths E&M: 2.38, 2.40, 2.52, 3.1, 3.8, 3.9, 3.14 [Due Tuesday October 3, 11:59 pm] |
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5. October 2 | Chap. 3 Oct. 3: title summary Oct. 5: title summary |
Read: Griffiths E&M: Finish Chapter 3, start Chapter 4 Problems (PS5): Griffiths E&M: 3.18, 3.23, 3.24, 3.35, 3.41, 3.42, 3.45 [Due 11:59 pm, Tuesday October 17] |
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6. October 9 | Chap. 3 Oct. 10: Midterm Break summary Oct. 12: title summary |
Read: Griffiths E&M: Chap. 3 Problems: wrapped over from last week Some suggested study problems for the exam: Chap. 1: 1.33, 1.41, 1.53, 1.58 Chap. 2: 2.1, 2.39, 2.41, 2.45 Chap. 3: 3.10, 3.15, 3.25, 3.38, 3.48 |
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7. October 16 | Chap. 3/4 Oct. 17: title summary Oct. 18 (7-10 pm, Merrill 211): Midterm Exam Oct. 19: title summary |
Read: Griffiths E&M: Chap. 4 Problems (PS6): Griffiths E&M: 4.2, 4.3, 4.5, 4.8, 4.10, 4.29, 4.33 [Due 11:59 pm, Tuesday Oct. 24] |
First Midterm Exam: Wednesday, Oct. 18, 7-10 pm |
8. October 23 | Chap. 4/5 Oct. 24: title summary Oct. 26: title summary |
Read: Griffiths E&M: Chap. 4 & 5 Problems (PS7): Griffiths E&M: 4.15, 4.16, 4.22, 4.25, 4.38, 5.6, 5.38 [Due 11:59 pm, Tuesday Oct. 31] |
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9. October 30 | Chap. 5/6 Oct. 31: title summary Nov. 2: title summary |
Read: Griffiths E&M: Chap 5 & 6 Problems (PS8): Griffiths E&M: 5.21, 5.36, 5.39, 5.50, 5.51, 5.61, 6.3 [Due 11:59 pm, Tuesday Nov. 7] |
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10. November 6 | Chap. Nov. 7: title summary Nov. 9: title summary |
Read: Griffiths E&M: Chap. 6 / 7 Problems (PS9): Griffiths E&M: 6.7, 6.16, 6.18, 6.23, 7.4, 7.8, 7.13 [Due 11:59 pm, Thursday Nov. 16] |
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11. November 13 | Chap. Nov. 14: title summary Nov. 16: title summary |
Read: Griffiths E&M: Chap. 7 / 8 Problems (PS10): Griffiths E&M: 7.16, 7.22, 7.26, 7.35, 7.42, 7.45, 7.60 [Due 11:59 pm, Friday Dec. 1... but these are also good exam practice problems, so I suggest you look at them earlier.] |
some suggested exam practice problems: 4.11, 4.13, 4.18, 4.24, 4.28, 4.34 5.3, 5.9, 5.11, 5.13, 5.15, 5.22, 5.26, 5.46 6.5, 6.9, 6.10, 6.12, 6.17, 6.21, 6.27 7.3, 7.7, 7.10, 7.17, 7.20, 7.28, 7.31, 7.39, 7.58 |
12. November 27 | Chap. Nov. 28: title summary Nov. 30: title summary |
Read: Griffiths E&M: Chap. 8 / 9 Problems: Griffiths E&M: 8.2, 8.3, 8.5, 8.12, 9.32 [Due Tuesday Dec. 5, 11:59 pm] |
Second Midterm Exam: Wednesday, Nov. 28, 7-10 pm |
13. December 4 | Chap. Dec. 5: title summary Dec. 7: title summary |
Read: Griffiths E&M: Chap. 9/10 Problems: Griffiths E&M: 9.6, 9.13, 9.16, 9.30, 9.33, 10.9, 10.21 [Due Wednesday Dec. 13, 5:00 pm] |
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14. December 11 | title... Dec. 12: title summary Dec. 14: Reading Period |
Practice exam problems: Chapter 8: 8.4, 8.7, 8.13, 8.15 Chapter 9: 9.2, 9.8, 9.19, 9.22, 9.34 Chapter 10: 10.2, 10.10, 10.13, 10.20 |
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Finals week | Final exam: Tuesday Dec. 19, 2-5 pm, Merrill 211 |