Notes on electric forces and fields

My notes for the non-calculus class (PH102) may be handy from time to time. The next several day's material corresponds to Ch. 2-3 in the notes.

(warning, ~23Mb PDF file)

A quick survey

You all have a pretty diverse background, and I want to make sure that I'm not getting you in over your heads. It would be helpful for planning purposes if I knew a little about your math, programming, and electronics experience. Can you answer the following (very short!) survey?

The survey is totally anonymous, and the results will not be seen by anyone but me. It is really just to get a grasp of the baseline skills you're coming in with so I can tailor course topics (and especially the labs) to what most of you are comfortable with. Please answer as honestly as possible to make this as useful as possible to me; if you really don't feel like you understand one of the topics, don't select it (even if you think you're supposed to understand it).

The survey is here if you wouldn't mind ...

[If you're not in the class, and just saw this on Twitter/Facebook/etc, please answer "no" to the last question.]

Online Matrix Calculator

Neat stuff. Very handy for those circuit problems ...

More last minute thoughts on the exam

UPDATE: I made corrections & additions to the HW3 solutions today, might be worth a last-minute check.

So I've actually made it now, and I think you will be fine. I am going to do the problems again myself just to be sure the timing is somewhat reasonable. A few of random thoughts:

• As promised, the exam has 4 problems, you can solve any 2.
  
• There are no terrible integrals involved. Just polynomials and so forth, no weird arctans or anything.
• For most of the problems, there are at least two straightforward methods of attack. This is on purpose, with the hope that you'll see one of them quickly.
• Two problems will favor those of you that remember the basics of mechanics, two problems will favor those of you that like the math.
• The binomial approximation is just about the coolest thing ever. Know when you can get away with it.
• There are no numbers on the exam (except things like pi and 2, possibly a 3). A calculator is not useful unless it happens to do symbolic math.
• It is fine with me if you bring an complex calculator that does symbolic math. The basic rules are no pc's, no cellphone calculators, no PDAs that have wireless communication capabilities.

Anyway: if you've been able to follow the homework so far, the exam problems will seem almost laughably easy. The only real issue is time pressure: you get about 20 minutes per problem, so

• Use your time wisely, and watch the clock.
• Don't get stuck on anything - if you find yourself stuck, see if you can make a simplifying assumption to move on (this might entail some lost points, but many less than not finishing the problem at all), or pick another problem
• In spite of the time pressure, spend a few minutes reading and thinking about all the problems before starting. Make sure you really know what is being asked, and have a physical picture in your mind before moving on. If you can't at least see the 'flavor' of the answer, math is probably not going to help.
• Please, please make sure you read the problems you choose to answer a second time, there are multiple parts to some of the problems.
  

I'll be up another couple of hours if you have questions.

Draft of formula sheet

Here is a first draft of what I'll give you tomorrow with the exam. I have a bunch of other formulas to add yet, and some useful integrals, but I think you can get the idea of what will be there and what you don't need to include on your sheet.

I'll post again when I've finished a more complete draft, probably in a couple of hours.

UPDATE: a few changes to the formula sheet, this is a nearly final draft.

Exam on Friday

A few stray hints for the exam on Friday.

• It is only an hour exam, so there will be four problems. You solve any two of them. Heavy partial credit is possible.
• There will be a formula sheet with all the basics. You are additionally allowed to bring in one sheet of standard 8.5x11 inch paper with whatever you like on it.
• Your formula sheet will contain fundamental constants and integrals you will need.
• Understand the derivation of the (approximate) dipole potential ...
• Reading through my old PH106 homework solutions might be helpful, just for some examples of worked problems. HW 1-4 are relevant, mostly.
• If need be, the exam will be scaled ... so relax :-)

I'll be around Bevill most of the day tomorrow if you want to drop by the office with questions. If you're busy in classes tomorrow, I'll try to respond to email questions rapidly.

SPS study session

"Society of Physics Students is hosting a homework help session Wednesday, September 16 at 6:00pm in 109 Gallalee. Anyone needing help with physics is welcome to attend."

Office hours today

If you're having trouble with homework, I'll be in Bevill from 3:30 onward today (until about 5:45).

If I'm not in my office, Room 228, try my lab, Room 180.

Help desk schedule

Once again this semester, all 100-level physics teaching assistants are pooling their office hours to better assist you. Here is the current schedule. Office hours are in 203 Gallalee.