Final grades are posted

Well, it is done. Your final grades have just been posted. If you are interested in what your final exam score was, you can check Moodle, which now has everything up to date.

General comment on the final exam: only one person changed by a letter grade after the final exam, mostly you stayed about where you were. The problems were much, much better than the multiple choice, which I sort of expected. Overall, I was pleased.

The multiple choice section of the final was scaled by about 16% upwards to enforce an average of 75%. The problems section actually had an average of exactly 75%, so no scaling was necessary - good work! The final exam grade is then the average of the scaled multiple choice and the problems grade. Below is a histogram of the overall final exam grades:


It is perfectly symmetric, which is just ... creepy. So it is: 75% average, perfect bell curve.

A similar plot of overall final course grades is below. The average grade for the course was a 78%. Keep in mind that when assigning letter grades, I always round up (so 79.01% is a B-, 78.99% is a C+) - thus translating the plot below to the number of A's, B's, etc. is misleading.


Anyway: have a good vacation, and take a much-needed break. Feel free to email or call me with questions about your grades, or anything else.

Initial grading is in

The final grades will be curved, definitely.

I just finished grading the multiple choice part last night, and the average was about 60%. I will scale the multiple choice part upward so that the class average is a 75%, which in the end means adding about 15 points to everyone's grade. (The distribution was still nicely Gaussian, with a decent spread, so just adding points is OK.)

The problems will be scaled separately if need be; I have not started grading them yet.

Basically, I don't want to have everyone's grade brought down at the last minute (this is both unfair and distasteful), and usually it ends up that about half the class improves, half goes down, but almost no one makes a huge jump either way. My finals are more or less just a last chance to make sure that you learned what I think you learned and your grade is where it is supposed to be ... not a last chance to wildly alter it.

So anyway: rest easy, it will almost certainly not be as bad as you thought. I will post here when it is all finished.

Last-minute office hours

This morning I'll be in my Gallalee office, starting at about 10:15 for any last-minute questions.

If you don't see me there, I might be up in the physics office (2nd floor) making copies of the exam ...

Seriously ...

Cramming might best proceed in this order:

Example problems
Previous exam solutions
Review the cheat sheet

Remember that the final is 11:30-1pm, in the usual classroom.

Tide-related physics problem

No, I'm not kidding.

In the spirit of randomness, here is a random picture:


It is taken at a temple in Kyoto, Japan. While you're cramming for the exam, ponder this: why do the beams seem to bend? I recall them being perfectly straight in person, if a bit narrower at the top ...

Also, my dog Dingus is really pulling for you all to do well:

Cheeeet Sheeeet

Here is an example of what I'll be giving you tomorrow.

Caveat: it has not been proofread, it is subject to change, may cause temporary blindness, etc.

(Probably, it will not change much by tomorrow, though, save proofreading.)

Last minute questions & answers

ONCE AGAIN: All but number 13 have solutions now. Number 13 will not be on the final.
YET MORE: number 14 is now solved.
UPDATE: review problems 8, 11, and 12 have solutions now. The rest are on their way ...

I should be available most of the weekend by cell phone, facebook, email, or IM (username "uaphysics", AOL IM account).

Shortly, I will post a few more solutions to the exam review questions, and should have them finished this evening. I'll put an update here when that happens.

Studying for the final

Here's what I just wrote one of you in an email. I thought it would be useful info for everyone to see.

PH102 and PH106 do cover basically the same material - the only real difference is that PH106 uses calculus, and PH106 does not. (Well, also PH102 covers modern physics, and PH106 does not).

I would say looking at PH102 homework problems and exams is probably just as good as looking at PH106 problems - the sorts of problems are exactly the same, the only difference from what I'll ask on the final is a bit higher level of math.

Narrowing it down, probably the Spring 2008 homework sets are the most valuable of all the PH102 stuff, followed by Spring 2008 exam 2 and the Spring 2008 final exam. A good approach would be to look at both the PH102 and PH106 homework sets for the problem part of the exam, and the quick quizzes in the text for the multiple choice part.

Exam review questions & solutions, grades

UPDATE:

Moodle grades are now current, and should reflect all homework sets, quizzes, labs, etc. Check them carefully to make sure I haven't missed anything ... you can regard these as your pre-final grades, if I haven't made any mistake.

Your total grade thusfar is 75% of your total grade, the final exam counts for the last 25%. This should be enough info to calculate what you need on the final exam to get a particular grade :-)

Keep in mind: I follow a 90/80/70/60 scale for A/B/C/D. Plus and minus grades come at 2.5 point increments. I always round up - so 89.001% rounds up to 90%, for an A-.
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Partial solutions to the exam review questions are here.

I'll be posting updated solutions, and probably some more example questions, some time tonight.

I will also be updating your grades on moodle tonight ... once that is done, it should include everything except the final. I'll post again when that is done, and how you can estimate what grade you need on the final ...

Updated HW solutions

UPDATE:
The solutions for HW8 and 9 are now completed and online, as are partial solutions for the final exam review questions. You can find everything here.
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I have updated the solutions to HW7, completed all but one solution to HW8, and finished about half of HW9.

I should have the rest of HW9 finished tomorrow, and I will also post the solutions to the final exam practice questions.

You will be well-prepared for the final exam, I promise. No surprises.

Material covered on the final

As you hopefully realize, the final exam is comprehensive. Below is a list of the chapters and sections that are included. Some specific sections of certain chapters will not be included on the final.

Ch. 23 - all
Ch. 24 - NOT 24.5
Ch. 25 - NOT 25.7,8
Ch. 26 - all
Ch. 27 - NOT 27.5,6
Ch. 28 - NOT 27.6
Ch. 29 - NOT 29.6
Ch. 30 - NOT 30.8,9
Ch. 31 - NOT 31.7
Ch. 32 - ONLY 32.1,2,4
Ch. 33 - NONE
Ch. 34 - NONE
Ch. 35 - ONLY 35.1-5,7,8
Ch. 36 - ONLY 36.1-4

One can logically group the chapters into sections, I think:

Ch. 23-26: electric fields, forces, & energy
Ch. 27-28: circuits
Ch. 29-32: magnetism & induction
Ch. 35,36: optics

Your final exam will have two parts. The first is multiple choice questions, worth in total half of the final exam grade. There will be about 20, they will be mostly conceptual in nature (like the 'quick quizzes'). The second is problem solving. In this case, you will have approximately four problems for each of the four sections above, and you will be required to solve two in each section. Thus, out of a total of 16 problems listed, you need to solve 8.

You will be given an extensive formula sheet and all requisite physical constants, etc., and are allowed to bring in two 8.5x11in sheets of paper with anything on them you like.

More details will follow as the final gets closer.

Final exam review

I have made up a list of problems that will be useful for you to review for the final exam, which you can find here. Some of the questions should be familiar, some should not, but they should all be ones that you can solve.

I will also post some example multiple choice questions soon. Other useful study aids are your homework sets, and the example problems and 'quick quizzes' in your textbook. Finally, some of my previous PH102 material will be helpful - there are a good number of solved problems included in the PH102 homework, exam, and quiz directories.

This problem set will not be graded, it is only for studying purposes. I will post solutions to all the problems over the break at some point as well.

Lab for today

Today we'll investigate converging and diverging lenses. It should be a reasonably short activity.

I'll also give some details about your last homework set in class today, it is not quite ready yet. It will be an exam review.

Moodle grades are up to date

I just updated the grades on Moodle ... they now include everything outstanding *except* homework 8. All labs, quizzes, etc. are otherwise included.

Remember that your papers counted for 2 homework sets, and please check through everything carefully to make sure the gradebook agrees with your own records (or recollections at least).

Tomorrow we'll move on to lenses, which I'll post more about later. If you were to skim through the relevant chapter in the book before tomorrow afternoon ... that would be great :-)

Also, I'll be posting your last homework set soon, which will be a small review for the final exam.

Today's lab

Today, we'll do a short experiment on total internal reflection.

I opted to do this shorter experiment instead of the longer lab on mirrors so we have some time to go over homework problems ...

Multi-touch screen videos from today

Here is a link where you can watch the multi-touch screen demo videos from this afternoon's lecture.

Lab for today

Here you go, we are starting optics!

Recitation today

I just wanted to post a quick note to say I'm sorry I unexpectedly wasn't at recitation today, since I had mentioned earlier in the week we'd cover a bit more on EM waves. Somehow, it slipped my mind that I had agreed to go to a local elementary school and work with some 5th graders ... but I knew you'd be in good hands with Neha.

For the record, it was fun, and they were a pretty sharp bunch. And, if it makes you feel any better, I was still teaching physics today, just in a different location.

Anyway: as penance, we will spend a good deal of time on Monday working out homework problems. So enjoy the game and the usual craziness associated with it, but don't forget to read Ch. 35 before Monday ...

Homework 9

Homework 9 is out. It is due next Friday, 21 Nov. 2008. This is the second-to-last homework set ...

Exam II solutions

Except for the last problem (which is an example problem in your textbook), I have preliminary solutions up for exam II, as well as the original exam.

Let me know if you see any errors or have questions. Good study material for the final ...

Moodle grades are up to date

UPDATE (Wed 12Nov08, 02:25): There were a few mistakes in the lab grades as posted, and I have made the requisite changes. I think everything is correct now, but please check your grades carefully to make sure everything seems OK.

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I have updated your grades on Moodle, which includes all work to date excepting the assessment results (giving you bonus quiz points) and the papers (giving you 2 new homework grades). Both of those should be up tomorrow.

One thing to note that is new: the individual quiz grades have now all been scaled upward to ensure an average of 75% on every quiz. That means basically you can add the following number of points to each quiz:

Quiz 1: 24
Quiz 2: 9.4
Quiz 3: 15
Quiz 4: 15.5
Quiz 5: 0
Quiz 6: 11.8
Quiz 7: 6.6
Quiz 8: 0

So, take your raw percentage score from each quiz, and add the requisite number of points listed above. Quizzes with "0" listed mean that the average was already more than 75% for that quiz. The quiz averages have tended to be fairly low so far, so I have scaled them all upward to compare more favorably to the other components of your grades (HW, Exams, etc), which all have class averages in the 70-80% range.

Anyway: check your grades carefully, to make sure I am not missing anything, and to find any errors. We have done our best to make sure everything is correct, but mistakes can happen.

Finally: this affects only a few of you, but the grading software will not deal with percentages over 100%. If you scored over 100% on the last exam due to bonus points, your exam score has been rounded to 100%, and your overall grade in Moodle will be slightly lower than what it actually is. I will give you detailed grade reports on Wednesday that will not suffer from this problem.

Exam II results ...

So, it was a bit mixed. Here is the distribution:

The exam average was 76%, with a standard deviation of 20%. About half of you received A's or B's on the exam, which is good. On the other hand, about half of you are well below the C mark, which means we have some work to do. I may end up scaling the exam a little bit, and will decide that soon.

We will go over the exam solutions in class today, and based on these results, review a few things I think we need to spend more time on.

The exam grades, along with up-to-date labs, quizzes, HW, etc, will be on Moodle some time later today. I will also have your papers back this week, but probably not until Wednesday ... at which time, I will give you each a summary of your overall grade to date, broken down by category.

Wheatstone.

Formula sheet

This is what I'll give you on the exam tomorrow.

Impending Exam

So the exam is made. You would do well to study the example problems in the chapters listed in the previous post ...

Also: Helmholtz Coil.

Friday's exam

The exam is basically going to cover chapters 28-31, but not quite every section. Specifically, the following sections are "fair game:"

• Ch. 28, Sect. 1-5
• Ch. 29, Sect. 1-4
• Ch. 30, Sect. 1-7
• Ch. 31, Sect. 1-7

More or less, these are also the sections I focused on more in the lecture periods. The exam will have a total of 6 or 7 questions, and you will have to pick 3 of them to solve. All problems will have equal weight, so you can really choose any three problems you like and solve those. There will be heavy partial credit, so even if you can't finish a chosen problem, get as far as you can and show as much work as possible. The more I think you knew what you were doing, the better you will do.

The problems will be similar to the homework problems, but easier - not as many steps, not quite so much math. Not so easy as the quiz questions though. You can bring in one formula sheet, front and back, with whatever you like on it, and I will also provide the basic formulas and numerical constants required.

My suggestion is to study the homework solutions and the example problems in the textbook. This one is going to test problem solving ability more than memorization, so the logical thing to do is solve as many practice problems as you can.

For example, you could look here for some good solved problems.

HW 7 partial solutions / Quiz answers

Solutions to homework 7 are out, excepting two problems. I will try to get the solutions finished tomorrow, but the problems missing solutions will not be on the exam.

Also, the answers to all quizzes are now online; you can find all quizzes and answers in this directory.

HW 6 solutions

Here you go.

Homework 7 solutions should follow some time tonight, along with quiz solutions.

Tomorrow's lab / HW5 solutions

Tomorrow, we'll do a lab on mutual inductance. Or, wireless power if we want to sell the thing a bit more.

Also, HW5 solutions are now out. HW6 and 7 solutions should follow later today, I will post here when they are ready. I will also post details about Friday's impending exam later today ... but a good start is to study the HW5 solutions.

Today's exercise

Today you will build a motor, with nothing more than a battery, some bits of wire, a deck screw, and a little magnet.

Homework 8 is out

This is delayed a couple of days, but so is the corresponding due date.

Homework 8, due 10 Nov. 2008.

Moodle is up to date

Your grades are now up to date on moodle; this includes basically everything to date *except* the papers. I'll read those this weekend ...

Answers to a few common questions:

1. What various stuff is worth can be found in your syllabus.
2. Two labs have been dropped, one homework and one quiz have been dropped.
3. If you were given a "bye" on a lab or quiz for an excused absence, this is not yet included. (In this case, your grade can only be better than what is posted, slightly.)
4. For some of you, the homework is really killing your grade. It is not that most of you are not scoring well - on the contrary, the average for those of you that do the homework is about 75%. The problem is that 20% of you are not doing the homework at all. Turning in a half finished homework is better than nothing, or even just turning in every other one. It isn't too late ... so please, mend your ways. I am available for help.
   

Anyway: if you have questions, just send me an email or grab me after class.

Lab / due dates / grades

Right! My being out of town for nearly a week means I am behind on this thing, and a few updates are in order. They get less urgent as you go down the list, precipitously.

Item the First: we have a shiny new lab for Wednesday, which is all about induction. Basically, we are making a transformer, though the lab doesn't just come right out and say that.[1]

Item the Second: your next exam is not, in fact, this Friday (Halloween). It has been moved one week forward, to Friday, 7 November 2008, during the recitation period. It will be entirely problem-based, and not cruel. It will go something like this: I give you 6 problems, and you pick any 3 of them to solve. The values of "3" and "6" are subject to change as the exam approaches.

Item the Third: your current homework set is due on Wednesday (formerly, this past Friday). Don't get so excited about the extension that you forget to do it ;-) Of course, since we did the remaining problems in class today, this is not so much a problem I suppose.

Item the Fourth: by Wednesday's class period (probably by Tuesday evening) your up-to-date grades will be posted on Moodle. Just in time for Drop Date, on Wednesday. If you think you are in some danger, come see me and we can discuss things.

Item the Fifth: before your exam comes, I will have the missing homework solutions online. I have actually solved all the problems, it is the typesetting that I am a bit behind on ...

Finally: for some reason, I am listening to The Cure as I type this. Did it just become 1992 again? Is this savage time warp localized to my particular living room, or is it widespread? Check your wardrobes carefully before going out ... this could get serious. [2]
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[1] Parenthetically, we are usually doing something much more clever than it looks like at first sight ... this is one case where I think utility of what we are doing will be more apparent however. This is more due to the writeups not being all that clever sometimes, less than it is because you are missing something. Given more time, we should really go back after each lab and make sure why we were doing it was clear.
[2] This is mainly here just to see if you read the whole thing.

Next Homework ...

Here you go.

Due Friday, 24 October. We will try to give you plenty of time in class this week to work on this and your papers.

Wednesday's experiment

We'll measure the earth's magnetic field.

Just FYI: next week, you will have most of Monday's class to work on your papers.

And now, for something completely different:

You will not have a new homework set until this Friday. Why, you ask, is there such a large gap between the homework set you have due today, and the subsequent one?

That is because you are going to write me a paper over the next two weeks. Seriously, a physics paper. It will be fun, I swear.

Instead of just calculating things all day long, you will write me a little paper which puts what you have learned in a broader context, and relates physics to everyday life and your career path. You will have two weeks to research and write these papers, in small groups, and I will devote most of one class period next week to this task.

More details will follow in class. Successful completion of the paper will count as much as two homework sets.

This is a group activity, and only five double-spaced pages ... if you work efficiently in teams, this will not be a lot of work, but has the potential for an easy 'A.' There will be bonus points for the top paper (as judged by me), in an amount to be determined.

Next Homework ...

Here is the next homework set, due on 13 Oct (one week from now). We'll go over a few of these on Wednesday in class to get you started.

While we're at it, here are the solutions to today's exercises. Hopefully I'll be able to get HW5 solutions up in the next few days.

Today's exercises

A few mixed exercises, as review.

Also, your next homework set will come out later today, and will be due next monday.

Finally, I have scaled exam 1 by 5 points uniformly. This brought the average to 76%, and the distribution remained sensible. The larger fraction of you are in the "B" range ... keeping up on the homework and labs will make the difference between an A and a B if you fall in this range.

Homework 6

So, take a break this weekend. Homework 6 will come out on Monday (6 Oct.) and be due the following Monday (13 Oct.).

We are a bit ahead of one of the other sections now, so we will hold off on new problems for now, and probably take Monday to summarize a bit what we've done so far.

Friday's class

Friday, we'll do a short lab on RC circuits, since the quiz will be very simple.

As I mentioned today ... the quiz will be, verbatim, five of your exam questions. Study the solutions, and that is that.

Wednesday's class & lab

We'll start the class today by going over the most recent homework set, due by the end of the day. Number 6 is particularly tricky, we will set that one up in case you are having trouble.

Lecture-wise, we'll learn about RC circuits, briefly about diodes, and end with some more generalities about

We will also do a lab on dc circuits, in which we will learn how to do a proper 'four point' measurement and learn about a new component, the light-emitting diode. The hydraulic analog of a diode is a check valve, if that helps ...

Exam Grades

Your exam grades (as well as other updated grades) are available on Moodle now. The overall grade has already dropped one homework, one quiz, and one lab.

The exam results were mixed. On one hand, the average (70.8%) was not that bad, nor was the standard deviation (10.6), but the distribution shows a strong tail to the left:


I will probably end up scaling the exam upward by about 5 points, I will decide after more detailed analysis and let you know later this week. No one got 100%; 18/20 was the maximum score.

There is one prevailing theory to explain the average being a bit lower than expected, given that I thought the exam was far easier than the homework sets. Below is a scatter plot of homework scores (x axis) versus overall grade (y axis). There is a mind-bogglingly strong correlation between overall grades and aggregate homework scores.


So. If you do the homework, statistically there is a strong tendency for you do well in the class. Part of this is due to my tendency to reuse questions (in spirit, if not precisely). Part of this, however, is the fact that the homework assignments are constructed to get you thinking (and reading!) about the most important topics. It is not busywork ... I promise that if you grind through the homework, it will pay off. If you find yourself having trouble with the homework, you can always email me or drop by my office.

Anyway ... two main points: (1) the test will be scaled a bit, and (2) the homework really is worth your time, as much as it sucks.

Solution to today's ciruit exercises

Here you go. Includes an example of how to use Cramer's rule ...

Exam I solution

Here you go. You should get them back on Wednesday.

Today's exercise

Some problems on circuits. Practice makes perfect.

Wednesday we'll go about wiring up some more complicated and useful circuits.

Platonic solids made of resistors

You can look, but be sure to write down your own solution in your own words.

Sample formula sheet / Exam 1

Just heard on TV:

"It seems like you need to be a physics professor to buy a TV."

... this is not true. It does not really help. I was as bewildered as anyone else last time I bought one. Most of the complexity arises from marketing and intentionally vague specifications, not physics ...

Anyway: sample formula sheet. Something like this will be attached to the exam. Thus, anything you see on this example sheet you do not need to write on your own.

Recall: you are allowed to bring one sheet of 8.5x11in paper to the exam, with whatever you like on it. You will need a calculator as well; cell phones acting as calculators is strongly discouraged.

Lab procedure 24 Sept 08

Here you go, we will verify the rules for adding resistors in series and parallel.

Sample exam 1 questions ...

... are here. As you can see, they are based on problems you have already seen, and the actual exam will look similar to these questions.

On the real exam, there will be 15-18 questions.

I will put out a key for these soon, and probably add a few more (there should be more on Gauss' law, certainly).

Quiz, Exercise, and Homework solutions

Excepting the java applets we did, the solutions to all exercises, quizzes, and homework sets are now up. The easiest thing to do is start here and root around a bit. I tried to make the naming and hierarchy as obvious as possible.

I will try to update Moodle tomorrow so all of your grades to date are online, and will also try to post some example exam questions. I realize you have no good reason to believe me thus far, but the exam questions will really not be that bad ;-)

Finally, note the syllabus here, which tells you how much everything is worth.

Today's exercise

Current and resistance. Print one per group, you can put all group members' names on it.

Happy Birthday to Michael Faraday

Woot.

Checking grades online

I how have a system set up so you can log in and see your grades.

1) go here: http://faculty.mint.ua.edu/~pleclair/moodle/

2) Click on "Physics 106-4, Fall 2008."

3) Then, to log in to the system:

• your username is the first letter of your first name + your last name.

• Thus, if your name is "Jebediah Dingus" your username is "jdingus" ...
  

• your password is the last four digits of your CWID. You can change the password if you like after logging in.

Once you have logged in successfully, you should be at the main ph106 course page. There are a great number of things on this page, most of them are not useful. This is a new (and free) online course system I'm test-driving, so most things are just placeholders.

From this page, you can access your grades. You should see a link for "Grades" on the left-hand side of the page, about halfway down, under "Administration." For that matter, you can change your profile, create a little blog or discussion board, or all sorts of other things.

Any feedback you have on this system is helpful. Let me know if it works ... and I should have more grades entered early next week. Right now, only the first three quizzes and homework grades are there.

Homework 5 is out

Shorter homework, given the exam on Friday.

EDIT: In a moment of weakness, I have made HW5 due on Wed, 1 Oct. That is, next Wednesday, rather than this coming Friday.

HW4 solutions

Here you go.

Please read the homework solutions. They will be of great utility in studying for your exam this week, and they cost me a lot of time to produce.

McNair Scholars program

Just got the following I thought I'd pass along ...

We are currently accepting applications for the 2009 cohort of McNair Scholars. The deadline for submission of applications and recommendation letters is Friday, Nov. 7. More information is available at the McNair website, from Program Manager Dr. Nancy Campbell, or the Program Assistant Stephanie Hicks. Applications and forms for recommendations may be downloaded from the website or picked up at the office, 326 Osband. Eligibility criteria include: U.S. citizen or permanent resident; junior class standing by summer 2009; GPA of 3.0 or higher; potential for doctoral study; and either (a) first-generation college student with a qualifying income or (b) member of a group underrepresented in graduate study. McNair Scholars is a TRIO program of the U. S. Department of Education.

Foo!

Problem 1.7 is really interesting.

Exercise III solution

Here is the solution to the exercise we did on Monday. It is worth a read, I think, even if you solved all of them correctly - I added a few things here and there

Today

Today I'll be in my Bevill office (228) from about 10:45 onward, feel free to drop by.

I'll try to leave a note on my door if I duck into one of the nearby labs, you can also call my cell if I you don't find me there.

Image charges and conducting plates

Foo. Bar. Biz. Baz.

Tomorrow's Lab (17 Sept. 08)

Tomorrow, we'll investigate capacitors. Here's the procedure.

UPDATE: Alternate link, in case the symbols do not show up properly.

Yesterday's exercise / extra credit

Just a reminder: the fourth problem from yesterday's exercise (see previous post) is extra credit, worth 1/10 of a homework set. Bring it on Wednesday or email it to me.

As super-double-extra-credit, worth an additional 1/10 of a homework set, show that integrating the surface charge density over the whole plate gives you -q. I suggest once you find the density as a function of lateral position on the plate, integrating the area in polar coordinates, over r(dr)(dtheta), where r would be the distance along the plate.

Also, I'll be around my Bevill office until about 1:30 today if you have homework or other questions. Feel free to drop by.

Exercise for today

Today, in lieu of a laboratory, we'll work out some problems related to today's lecture.

Find them here; print one per group, turn in one per group.

Homework 4 is out

Here it is. I think it is easier than last week's ... there is definitely less math involved. Still, you would be clever to start on it early in the week.

Useful course notes

First, your reading for the next week is Ch. 26 in Serway, capacitance and so forth.

Second, here are some useful notes from an E&M course at MIT that are pretty well done. The mathematical level is roughly on par with what we have been doing, perhaps slightly higher in some places.

Third, I think I already mentioned this, but you might find my ph102 notes useful for separating the physical understanding from the mathematics.

Fourth, another random set of notes. This one is again from MIT (they are good about putting things online), but the mathematical level is somewhat above what we have been doing. If you bought the supplemental text, or have already had Calculus III, these might be worth reading through. Beware, these notes use a different set of units than we do! In the cgs units, Coulomb's constant is set to 1, and it will be missing from many otherwise familiar formulas.

Finally: expect HW4 to show up in the next hour or two. I got distracted yesterday by the brutal beatdown we inflicted on WKU and didn't quite finish it yet ... as a rule I try not to post HW until I have solved all the problems myself.

Homework 3 solutions

They are rather lengthy, so don't feel bad skimming over the problems you knew how to do. In particular I showed 3 different ways to do the first two problems, to try and give you a feeling for different ways to approach problems. There is always more than one way ...

Homework 4, on capacitance, will be out later today or tomorrow morning.

Today's recitation

Today (technically, since it is the very early morning) we will spend about half our time on the first two homework problems, so don't panic if you are having trouble with those two.

You may find this link useful for the second problem. Think about what effective area the pressure acts over to pull the hemispheres apart ...

Friday's recitation and quiz

Tomorrow, we will spend the first half hour or so going over only homework problems 1 and 2. More specifically, I'll show you 3 different ways to solve both of them.

After that ... the quiz. Read Ch. 25 and you'll be just fine for that.

By the way ... the recent poll had Friday as the preferred homework due date by an 8:1 margin. Thus, we will keep Friday as Homework Day.

Wednesday's lab

Here is the procedure. This one is not too difficult, and usually works out very well.

Please read through the procedure briefly before class, and make sure you have read Ch. 25 before tomorrow's class.

Homework 2 / Quiz 2 solutions

Here you go. I just finished writing them up, and will need to double-check and proofread them a bit more tonight. If you find any errors, let me know.

Quiz 2 and its solution are also online.

Wednesday's class / office hours

Tomorrow afternoon, I should be free most of the day from 1pm onward. Feel free to drop by my Bevill office (rm 228) any time after 1pm.

If you do not find me there, but my door is open, this means I stepped down to my lab for a little while, Bevill 180.

Wednesday we will not introduce much new material, but will mainly go over simpler, concrete examples of the fairly theoretical stuff we went over today. So, mostly it will be solving example problems, and applying the general things I talked about today. Part of that will be solving a couple more of the homework problems, and revisiting some prior homework problems with the new tools we have at our disposal.

There will also be a lab - our first real lab - and I will post the procedure for that tonight some time. Please try and give it a quick read-through before Wednesday afternoon.

HW 3 is out ...

Homework 2 solutions should come some time tonight. Homework 3 is now out, and due one week from today.

Next week's reading / Today's recitation

Next week, we'll be covering Ch. 25, "Electric Potential." Some of this will be familiar already (I hope) since we already talked about the work and potential energy required to build various charge configurations.

Today in recitation we'll use Gauss' law to find the force on a thin sheet of charge (more useful than it sounds). From this result, next week we will derive the energy stored in the electric field, and can start to talk about capacitors and real, live circuits.

After which there is of course a quiz.

If you have not already, I again suggest reading the quick quizzes in Ch. 24 in preparation for the quiz. The quiz is solely on Gauss' law, and requires no serious calculations.

As an aside, you might notice from the reading/lecture that there are really only three easy applications of Gauss' law in the way we are studying it:

1. long linear charges
2. spherically-symmetric charges
3. flat plates of charge

Anything beyond these three is usually either a) a trivial extension of one of the above, b) hideously difficult, or c) involves a stupid symmetry trick, but is of questionable utility. We'll do some examples of a and c tomorrow ... examples falling under category b are usually best solved by other methods.

Tomorrow's quiz

Once again, the quiz will be 5 questions, multiple choice, and will require very little calculation.

It will be derived from Ch. 24 (Gauss' law); it would be particularly clever to read through the 'quick quizzes' in that chapter.

We will also go over how to tackle question 2 on the homework (that is, we will mostly just solve it in class). It turns out that this problem gives roughly the right answer for a hydrogen molecule, for completely the wrong reasons ...

Partial HW1 solutions

I should have these finished up later in the week, and a bit better proofread.

This day in nerdery ...

1803: English chemist-physicist John Dalton starts using symbols to represent the atoms of different elements.

Wednesday's class

First, we will discuss Electric Flux and Gauss' law (Ch. 24) for a while ... including a look at the current homework set.

At least the first two homework problems on the homework will require a bit of sneakiness involving Gauss' law. The third ... well ... you should already know how to go about it at least. I strongly suggest the energy minimization approach, which I will outline for you. By the end of the day, we should have covered most of Ch. 24, and you should have a good head start on the homework.

Then, we will explore what we learned about Gauss' law with some applets.

Reading for this week

In case I failed to mention it ... the reading for this week is Ch. 24 in the Serway book.

If you can, read it before class tomorrow. If not, make sure to read through it by Friday of this week ... it may make more sense after the lecture tomorrow (hopefully).

Short week, short homework

Just three little questions. And they don't even cover new material, really.

Due Friday, 5 September 2008 at 5pm.

Today's quiz and solution ...

I have put up a copy of today's quiz, and a key. I will try to post a more detailed solution later this weekend ...

Homework 1

Item the first: the homework is no longer due at the start of recitation. The deadline is extended to any time before 6pm on Friday, so you have a chance to ask questions related to the homework in recitation.

Item the second: look here. *Cough*

*UPDATE* there were some errors in the homework hint ... check the file now, it should be more clear.

Today is add date

Today is the last day to add a course ... that means if you are not yet registered, but are attending class, you should do so *today*. Let me know after class if you have questions about that, I'll help you out.

Also: after an email from one of you today, I realized that there was essentially nothing on the course calendar, technical snafu on my end. Now the whole course calendar should be up to date, including what chapters we will be covering on any given day (so you can read them ahead of time ...)

In today's class, we will basically do a math overview, so we're all on the same page, and work out some of the homework problems. And by "some" I mean "most." Friday, we'll begin a bit of Ch. 24 (Gauss' law) and have a very short quiz on electric forces. It will be easy.

Next week, keep in mind that Monday is Labor Day ... and hence there is no class. Wednesday we'll continue with Ch. 24.

Math

Well. My bad ... after talking with some of you today, I realized that what I presumed Math 126 covered, and what it actually covers are two different things. I apologize for the oversight, and I feel really bad that some of what I've been doing has been a bit beyond your prerequisites. It was not intentional, and it is not too late to adapt.

So, here's what we'll do to rectify the situation. First, we will slow down a bit, and more carefully explain the math that is being used ... part of my speed was based on the incorrect assumption that you had already seen the math before. I'll try not to skip as many steps.

Next, on Wednesday, we'll review everything to date, using nothing more than single integrals, and put things in a somewhat simpler form than we have so far.

On Wednesday, I will also give you a crash-course in multiple integrals and other sorts of math you probably haven't really seen yet. We'll not prove a lot of theorems, or formally justify a lot of it, but rather I'll give you enough information to use some powerful tools we'll find useful. Just enough to get the job done, because believe it or not, having some more powerful tools at our disposal will make things easier in the long run. Really, it won't be a lot, just extending what you already learned in Math 125 a tiny bit.

That being said, from now on I will try to be a bit more aware of what math you are supposed to know already, what I should teach you along the way, and what I should avoid all together. For example: doing integrals over a path, surface, or volume, so far as they are useful to ph106, does not require much more than you've seen in Math 125, you just need to be shown it in a bit different manner. Mainly, it will be Useful to know how to set them up, and what they mean, but most of the time actually solving them is Not.

So anyway: from now on, I will try to be careful. This will be easier if you keep letting me know when I've gone a bit too far, as you did today ... it is not at all a Bad Thing to ask me to explain our methods in more detail when you are not quite sure you follow.

Today's activity

Today, we will run some small applets to get a feel for electric forces & fields.

This link should bring you directly to the applets. The username and password will be given in class.

Mathness

I made up some random math notes, regarding vectors and such.

You may also find my ph102 notes useful - same material, very little math. You want this file ... fair warning, it is a 26Mb PDF.

Recitation today

So. Today we'll slow it down a bit, and there are only two things we need to do.

1) Work on the homework problems
2) Take a small assessment test on electricity and magnetism.

The latter thing is ungraded, and has two real purposes. First, it lets us see which areas are most deserving of attention, and what you (as a whole) are likely to have the most trouble with. Second, it lets us (and by 'us' I mean the administration) see how well we actually teach you the material.

Related to the latter point, you will take the same assessment test at the end of the semester - the same material as a pre- and post-test to gauge how much you actually learned, vs. how much you knew already.

As a small incentive, if you successfully complete both assessment tests, I will drop one additional quiz.

Syllabus / prerequisites

As promised, here is the syllabus.

This contains all of the official sorts of information you might need, feel free to comment here or email me if you have questions.

I may make minor changes as I discover errors, or find something is possibly unworkable; I will post any updates that are made.

The full course calendar should be up by tomorrow afternoon. All you need to do before Friday is have a look at the homework. I'll give you one hint: the problems get easier toward the bottom. More serious hints to follow in Friday.

* One of you mentioned today that you may be eligible for transfer credit for this course. Please remind me of this on Friday, and I will have more information for you.

** Some of you do not have the proper prerequisites. Math-wise, the math today was about as hard as it is going to get; if you followed along well enough, you will probably be fine in that regard. Physics-wise, if you do not have ph105 credit, you are almost certain to have graduation troubles down the road ... you can stay in ph106 if you feel comfortable, but keep in mind you may need to take ph105 anyway at some point. Please come see me to further clarify these issues; I have information on this topic.

Intro slides

Here you can find the slides I used today, which includes all of the official course information (as well as a few figures I used for electrostatics). A proper syllabus will follow in the next hour or so.

Friday, we will spend some time reviewing what we covered today, and solve a few additional problems.

Homework 1 is out

Your first homework is out. It is due at 5pm on Friday, 29 August 2008. You may collaborate, but everyone must turn in their own work.

EDIT: change of heart; homework will be due at 5pm each friday, rather than at the start of recitation, so you have time to absorb last-minute hints from recitation and finish it off.

Join us.

There is a Facebook group for this section of ph106. We hope this will help you get to know the other students in this class, and provide a forum for asking questions.

Working together on homework sets is encouraged, this is one way you can enable that.

Welcome to Physics 106

This is where you will be able to find all information about your section of ph106.