Final Grades are on Moodle

Check it out. This includes *everything* - homework 4, the extra credit, etc.

Your "Course Total" in Moodle may not quite match the "Final Grade" column, as this does not include the extra credit. The "FINAL GRADE" column is what you should pay attention to.

The official grades will be posted tomorrow some time on MyBama ... consider these unofficial, until I double & triple check the gradebook tomorrow morning. I don't expect anything to change, but fair warning and all ...

Lastly, the +/- breakdown is like this:

A+ >= 97.5
A 92.6-97.4
A- 90-92.5
B+ 87.5-89
B 82.6-87.4

And so forth. I always round up, by the way - so a final grade of 89.1 gets rounded up to a 90 for an A-, not a B+. Similarly, an 87.44 gets rounded up to 87.5 for a B+, rather than a B.

Finals are graded

Well. The final exam grading is done.

The multiple choice average was 73.3% (std. dev 9.5%), and the average on the problems was 85% (st. dev 12.5%). That gives a raw weighted average (problems counted 25%, multiple choice 75%) of 76% (st. dev 8.5%).

The multiple choice average was a bit low, so I scaled all scores upward by 6.7 points, for a new average of 80% on the multiple choice section, and a new overall average of 81% (std. dev. 8.5%). That gave the following distribution:


Overall, there were 6 A's, 20 B's, 14 C's, and 5 D's - no one failed. You can see it broken down by question for both sections here:


Clearly, a few of the multiple choice questions were much harder than the others. For the record, only one of them came from the MIT Open Courseware. It is also clear that you chose to solve the problems that you had seen before, largely, which was of course quite clever ;-)

You should be able to log onto Moodle now and see your final exam score. Final grades will have to wait until I'm finished with HW4 and the extra credit assignments, probably some time tonight. I will post here when that is done. For now, the "course total" grade listed includes the final exam, but does *not* include HW4 or the extra credit.

For now, relax: the final went well, and no one failed.

A few more final exam details

The final will have two parts: multiple choice, and problems. The multiple choice section is worth 75% of the exam score, the problems section is worth 25%.

On the multiple choice section, there will be roughly 25 multiple questions, spanning everything up through optics. Roughly half will be qualitative (conceptual), roughly half will require simple calculations.

On the problems section, there will be two sub-sections. In each subsection, there will be 5 problems in total, you can solve any two of them. Thus, you solve a total of four problems out of ten - two from each group. All problems have equal weight, it will not matter which ones you choose. Heavy partial credit will be given, as usual. The sub-sections of problems are not grouped in any logical fashion, the five problems in each section will be a mix of topics.

Your final exam grade will then be calculated according to (exam score) = (multiple choice score)*0.75 + (problems score)*0.25. A certain degree of risk management comes into play here ... do not spend 75% of your time on something worth 25% of the points, and similarly do not spend 5% of your time on something worth 25% of the points. Pace yourself, and watch the time.

You will be given a formula sheet, you are additionally allowed to bring in two sheets of 8.5x11 inch paper, containing any information you like.

The exam will be 8-10:30am on Friday, in 227 Gallalee (the lecture hall). I suspect you will need the entire 2.5 hour period. The exam will be curved, if necessary, to ensure a reasonable class average.

Study your homework sets and exams, as well as the old ph102 exams and quizzes. And get some sleep before hand ... if you have been following things so far, there will be no surprises.

ADDENDUM: if you are allotted extra time for exams through testing services, and would like to exercise this option, we need to talk as soon as possible about scheduling.

Review session / extra credit

Tomorrow (Thurs), 3pm, Gallalee 329 (the lab room). I'll give more details on the final, and work some problems.

There is one last minute chance for extra credit ... here. A short two-page writing assignment that will magically turn your lowest quiz grade into a perfect 100%. The extra credit project is due by midnight Friday, if you choose to do to it. If you ask ahead of time, I will probably accept them on Saturday/Sunday as well.

(Really, it is not that much work. Basically, you watch a movie, and then write about it.)

Random end of classes updates

Ok, it is the end of days ... for ph102 anyway. Several things:

1) There is no lab on Wednesday. You can have the afternoon off to study ... or whatever it is you do. I suggest studying ;-)

2) The final quiz and lab grades are now up on Moodle, as is Exam II. Homework 3 will appear sometime Tuesday evening. After that, all is left is homework 4 and the final. Recall the grade weighting from the syllabus.

3) Homework 4 can be handed in with the final exam without a late penalty.

4) Somewhere in the depths of a heinous sleep-deprivation-induced lapse in judgment, I decided that the final exam will NOT cover waves, quantum or atomic physics (i.e., this week's material).

5) The final *will* cover Relativity, Electricity, Magnetism, Induction, Circuits (ac & dc), and Optics (i.e., everything except this week's material). Study your homework, old homework, and old exams. Oh, and the book and notes.

6) The final will be, contrary to previous rumors, more like 75% multiple choice and 25% problems. It will be held at 8am, this Friday, in our normal classroom.

7) The exam II average was 89%, with a standard deviation of 8.5%. Below is the distribution for exam 2, plotted as the percentage of people choosing each question, and of those, the average score. Clearly, each question should have had a 50% chance of being chosen if they were all equal. Apparently, they were not ... certain questions were perceived as being much harder than others ...

8) There may be a review session on Thursday. Stay tuned.

9), 10) Intentionally left blank.

11) This one goes to eleven.

Lab Today

Today, we'll measure Planck's constant, using LEDs and your lab boxes.

We should just get to the relevant material in lecture today.

HW 2 results

Well, the average was about 83%, with a standard deviation of about 10%. Here it is by question, plotted as the fraction of full points for each question:

If you are in to the last minute exam-cramming, you might want to look at the solutions for numbers 3 and 7. EDIT: I meant, look at those before the final, they will not show up on today's exam.

By the way: your homework 2 grades are now entered in the online grading system. When you get your papers back, be sure to make sure your total points add up correctly.

Office Hours Thursday

After class, I have nothing concrete planned until the exam at 3:30.

Feel free to drop by Bevill 228 any time between 12:30 and 2:45 tomorrow for last minute questions, or grab me after class.

Sudden change of plans ...

I think we need to take a breather. You all seem almost as tired and jagged as I am ;-)

Tomorrow, rather than covering the lenses material as planned, we will be reviewing for the exam. I think right now you would benefit more from solidifying the material we already covered, rather than moving relentlessly forward. We'll pick up optics again on Friday.

So here's the plan for Thursday ... about 9 hours from now: I'll review briefly the material relevant to the exam. I will also bring some exam-like problems to solve and work on the board. You'll come with questions, and problems you want to see a solution to. Anything is fair game ... so long as it is related at least tangentially to the exam.

I had more or less built one extra day into the schedule from the beginning, just in case, for things like this.

I suppose this means that if you think you are ready to just completely rock the exam, tomorrow could be a waste of time. Probably, though, in my heavily sleep-deprived state, I will let some important hint about the exam slip. One never knows.

Today's lab ...

... has two parts. One, and Two.

Pretty straightforward, maybe 90 minutes combined at best.

Exam II / Homework 4

The exam on Thursday (3:30pm, in the lab room) will consist entirely of problems, no multiple choice. It will be broken up into four sections. In each section, there will be 4 problems, you must pick 2 to solve in each section. Thus, you solve a total of 8 problems, and you will have about 2.5 hours to do it in. I expect you will need more like 1.5-2 hours.

The sections are:

1. dc Circuits (mostly Kirchhoff's rules) - solve 2 out of 4
2. Magnetism - solve 2 out of 4
3. Induction - solve 2 out of 4
4. ac Circuits - solve 2 out of 4

All problems are equal weight, you pick the two in each section you think you have the best shot at. There will be heavy partial credit - try to show as much work as possible.

There is nothing on EM waves or light included. You can bring in one formula sheet (8.5x11 in, front and back) and a calculator; the exam will include the minimal set of formulas you will need.

I suggest (strongly) studying last semester's homework and exam questions, and additionally the example problems in the book/notes. There will be a good number of problems that will look familiar. Also, it is crucial you don't get stuck on anything. Probably most of you will not quite finish 8 problems, maybe 7. Pick your problems carefully, and start with the ones you are most confident with. This will be an exercise in time management as much as anything.

All that being said, it will be a fair exam, no tricks. Just fair warning.

Well: there is also one more homework set to do, it is due on the last day of class. Here's how the last one will work: you solve all of the problems you didn't attempt on the exam as homework problems. Thus, you will also have 8 problems for homework 4. Probably, you will find that your classmates solved different problems on the exam than you did, and a group of 4 or 5 of you should be able to cover all of them ...

Partial HW3 solutions ...

... are out. By the time you read this, I will have stayed up late and finished another problem or two. Most likely, the solutions will be substantially complete by mid-afternoon tomorrow.

UPDATE: there are now solutions to every problem in fact, though for two problems I have just given links to existing solutions online. I hope to have my own version of those soon.

How to see your grades online

So, I have a system set up so you can log in and see your grades. Probably, I should have mentioned this earlier ...

Anyway, go here: http://faculty.mint.ua.edu/~pleclair/moodle/

Click on "General Physics II / Summer 2008."

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 ph102 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.

This is the system I'm planning to start using next semester ... and frankly, I'm using you to help me test things out. The system is perfectly secure - no one else will be able to see your grades or other information - it is the functionality and user interface I'm testing.

So: any feedback you have on this system is helpful. Let me know if it works ...

Online matrix calculator

Handy. Solves systems of equations and calculates determinants, among many other things.

By the way ...

I was just reading an interesting and very well thought out discussion that touched on professors assigning their own textbooks for a class. Interesting read.

This isn't strictly relevant, since a) my book isn't finished, and b) it isn't required, but just so you know, I had a few thoughts in response. Probably, I should not be sharing all of them ... but there are Things you should Know.

1) I don't make a dime off of the notes, and it will probably stay this way - writing textbooks is no way to make extra cash. If you bought printed copies of the notes at the SUPe store, you basically paid for the cost of printing - $0.15/sheet, full color. The PDF version online is of course free, and contains no material that is not my own work, or subject to an open-content license.

2) As an aside, the latter point is why many courses have password-protected pages or won't put slides online: they are using copyrighted images somewhere, and cannot just post those things online for free. That is the main reason I spent way too many hours drawing my own figures. Copyright law in the US is byzantine.

3) I don't really worry that you'll read the notes and not go to class. I've even taken and posted video of half the lectures or so, which should in principle worry me even more. I am either naive or arrogant enough to rely on my charm and your sense of responsibility ;-) Probably mostly the latter. Attendance is good for whatever reason, but so long as you learn the material, I'm happy either way.

4) I think the evidence suggests I'm following the notes more closely than the book, and therefore they have some utility. Ideally, you'll read both the notes and the textbook - probably, you will find that Serway et al. explain certain things better from your point of view, and sometimes I do.

5) It is true that sometimes profs do not have a choice of textbook. Particularly for intro classes, and classes where there are multiple sections. There are many reasons for this.

6) It is true that a good textbook is a good safety net when the lecture just doesn't make sense. Sometimes, its not your fault ...

7) It probably is, in fact, silly to spend huge amounts of cash on a book you won't open again after the class ends. In that regard, I wish my notes were complete. Keep in mind that point 5 means that there is almost always a good used textbook market.

Completed HW2 solutions

I finished typing up the homework 2 solutions, which might be a handy thing to study for the exam on Thursday (details to follow).

Also: I did take video of today's lecture, and put up the associated slides.

Lab for Mon 28 July 08

Today, we will investigate the behavior of ac circuits, using your lab boxes ... if all goes well, it should be a short lab.

If you find yourselves with extra time, I suggest hooking up an LED to the output instead of your RC circuit - seeing how the different waveforms behave is interesting. Then, try using the LED in parallel and in series with the capacitor.

Also: I have partial homework 2 solutions available. Probably, they will be finished by Monday afternoon.

Math Tests

I thought this was highly relevant ... not only is it good advice for, *ahem*, certain physics tests, it is also applicable to the GREs at least (and probably the MCAT, though I never took one myself).

The part about story problems is spot on. Read them like this at first: "Blah blah blah FIVE VOLTS blah blah TEN OHMS blah blah blah WHAT blah blah CURRENT." The answer is likely to be 0.5, independent of the blahs.

At least back in my day, the GRE math was almost identical to the SAT math. And story problems haven't changed much. "As I was going to St. Ives ..." (yes, that riddle in fact pre-dates Die Hard III)

Homework 3 is out

Here you go. It is due next Tuesday, 29 July.

We will do a couple of them in class tomorrow, and a few more on Friday.

Exam I results

Well, the exams are graded. You will get them back tomorrow, and we will go over the solutions.

No scaling was necessary - the average was 84.6%, with a standard deviation of 12.2. Very well done, better than expected. Here is a histogram, of sorts:


Since the exam was multiple choice, 20 questions long, each question was worth 5 points. Thus, saying the thing above is a histogram is being a bit too fancy; it is really just a plot of how many people got each score. Basically: many of you rocked the exam, and clearly studied. A smaller number of you did not rock the exam.

Now, if you are on the low end of the distribution, keep in mind that each exam is only 15% of your grade. Your homework, quizzes, and labs are all worth 15% each at the end of the class ... so a lower than expected exam score can easily be made up by doing well on the homework.

Basically: don't panic. It is still early enough. Be diligent about labs and homework, and things have a way of working out.

Below is a breakdown of the average score by question. Clearly, #20 was not your favorite. I suspect the problem was partly confusion of metric prefixes, and partly forgetting to take a square root ...



Perhaps not surprisingly, the questions I worked out in class today were quite easy for all of you ... a little present for showing up to lecture on the day of the exam, I guess.

And, by the way: we will go over new material tomorrow ...

Homework 2

Homework 2 is due tomorrow by 5pm. I will already be gone by then, so you have five options for turning it in:

• drop it in my mailbox in the physics office in Gallalee (2nd floor)
• drop it outside my office in Bevill (rm 228, folder on door)
• slide it under my Gallalee office door (1st floor)
  
• bring it to lecture tomorrow
• scan & email it

Labs for Wed and Thurs / this week's schedule

Tuesday: a bit more on magnetism, and some last-minute hints on HW2. HW3 will be out ... and you will get your exams back.

Wednesday: equipotential lines, somewhat out of sequence.

Thursday: mutual inductance.

At the last minute, I am going to have to be out of town on Wednesday and Thursday. Prof. Mankey will be giving the lectures on those two days. He will be covering new material, and will cover exactly what I had planned to go over. I will be in sporadic email contact while I am gone, and will be back in town on Friday.

Prof. Mankey has been doing this longer than I have, and knows what he is doing. Don't mistake my absence for a reason to miss class.

Your quiz this Friday will cover dc circuits and the first part of magnetism - basically what we covered last week Thursday through what we will do tomorrow. It will again be 5 questions multiple choice.

Quiz 2 results/solution

First, here is the solution to the quiz you took today. Second, below are the results:


Plotted is the average score by question, as well as the overall average. I will be scaling this, it seems - roughly, I'll add about 18 points your score to enforce a class average of 75%

Question 5 - calculating a resistance - was by far the easiest, it seems, as expected.

By the way: I reused all of these questions from last semester's quizzes. The first two questions are also right in the course notes.

Easiest way to study for the test: study what I've already asked in the past. If I asked it before, I probably think it is important, and that means I'm likely to ask it again, in some guise or another.

Homework I results

I have finished grading homework 1, and you will get it back tomorrow. It was quite good overall - the average was 92.8%, with a standard deviation of 9.8%. Here it is broken down by question, plotting the relative average score for each question:

Not a lot of conclusions to draw here. Either number 8 was very easy, or everyone paid close attention when I did it in class :-) Either way, it works for me - the end result is that you know something you didn't before, which was the main point.

Lecture video continues / Homework II

I have continued to post videos of the lectures, fyi. If you have missed some class lately - and some of you have - they might be worth some of your time.

On an unrelated note: I have moved the due date for Homework II to Tuesday, 22 July so you don't have a homework set and an exam on the same day.

This Friday's quiz ...

• 5 question multiple choice. Only two require calculation.
  
• Formulas given.
• Electric forces & fields, current & resistance.
• Nothing beyond material from Wednesday's lecture.

Exam I is Monday ...

Exam I is, as you know, scheduled for this coming Monday, 21 July. Perhaps the most notable thing about the exam is that it is going to be held during the lab period. That's right: no lab on the exam day. Sadly, there will be a lecture Monday morning as usual. No rest for the wicked, but as a small consolation, we will spend time reviewing for the exam during lecture.

Material
The exam will cover the following material:

• Relativity
• Electric forces & fields
• Electrical energy & capacitance
• Current & Resistance
• dc Circuits (through series & parallel resistors)

Basically, it will cover everything that we have done from day 1, through the end of Thursday's lecture. Friday's material (rc circuits, Kirchhoff's rules, etc) will not be on the first exam.

Format
The exam will be multiple choice, and roughly 25 questions long. I suggest studying the end of chapter questions in the notes, as well the homework and quiz solutions from last semester (start digging in here). In the book, you are best off studying the example problems, and the "quick quizzes."

Roughly half the questions will be conceptual or qualitative (no calculations), and roughly half the questions will involve real, live quantitative answers. With units and everything.

Location
The exam will be Gallalee 329, at the usual lab time of 3:30. I will devote the first 15-30 mins of that period to answering last-minute questions, after which you will have about 90 minutes for the exam. I expect the exam to take you closer to 60 minutes, but don't want anyone to feel too rushed.

Needs
You will want a calculator for the exam. Badly.

You can bring in ONE standard 8.5x11 inch sheet of paper front and back (or two sheets front-only), containing any information you like. This could include pictures, formulas, example problems, or even the first few chapters of "The Count of Monte Cristo" in a very small font. Whatever you think might help. You can use both the front and back, typed or written, crayon or pencil, your preference.

One interesting variant is to write from left to right with a red pen, and then turn the page 90 degrees and write over the top of that with a blue pen. If you can then lay your hands on a set of 3-D glasses ... presto, you've doubled your storage density.

Lab for Thursday 18 July

Today, our lab will have two sections: first, we will experimentally verify the rules for adding series and parallel resistors; second, we will investigate combined resistor-capacitor circuits and learn one way to experimentally measure capacitance.

So, here you go. Please only print one copy per group, as it is about 7 pages long. (Despite the length, it should not take much longer than yesterday's lab.)

Use all available resources ...

You may want to have a look through last semester's homework sets and solutions.

Problems I really like, I will sometimes reuse.

Of course, you are probably resourceful enough to have found this already ...

Lab for Wednesday 16 July

Tomorrow's lab has two parts.

Part the first, introducing you to the hardware and software you'll be using for the next several labs, including how to troubleshoot problems.

Part the second, in which you will investigate the behavior of different electrical components (e.g., resistors, capacitors, diodes). This lab will be partly qualitative, aimed at familiarizing you with the basic sorts of electrical components, and how they behave in circuits. Thursday's lab will be a more quantitative investigation of resistive circuits.

Print one copy per group when you arrive at the lab. Before then, have a read through each if you can, it will make things go far more smoothly.

Lecture video

By the way ... I'm still putting them up. Yesterday's and today's lectures are already online.

Yesterday there were some 'technical problems,' but today's video seems fine after a cursory overview.

UPDATE: the slides I was projecting in class were contained in the same file as I posted the previous day, here.

Homework 2 typo

In question 2, the separation of the two toner particles is in meters, though no units are given. The separation should be 1.2e-5 meters.

Various solutions

I have just posted a solution set for homework 1, as well as the 'quiz' from last Friday and its solution.

Also: I will try to get the first homework graded and back to you by this Friday, so you have a little feedback before the exam next week ... On average, a homework set like this takes me about 8-10 hours to grade, so we will see how it goes ...

Slides for 14 July 2008

Here are the slides I'll be using in class today. [~5Mb pdf]

If all goes well, some time Monday afternoon there will be video posted once again. It really isn't a lot of extra work so far to do the video, to be honest, except that I have to wear the earpiece. Is this a useful thing at all?

Moreso if I included a time index of when we covered various things (e.g., go 32m40s in to hear about capacitors)?

Lab for Mon 14 July 2008

Today, you'll do a lab on capacitors. Have a look at the procedure, it will probably take 90 minutes or better.

Homework 2 is out

You, know, in case you want to get a jump on things.

Once again, by the end of the week, we will have gone over all of the topics, and done many of the homework problems in class.

Lecture IV video

Video of today's lecture is online.

Update: the slides are the file from as yesterday. You should be able to play the movies in your browser now, if you have the right plug-ins installed. I recommend firefox + quicktime.

Video of today's lecture

I haven't had time yet to do any processing (say, to cut out our 10' break in the middle), or even watch it all, but here you can find the video of today's lecture, as MPEG or Quicktime. (The accompanying powerpoint slides are here.)

A couple of quick observations on this:

• The projector screen is still off-camera, so it is a bit annoying you can't see the images I'm referring to, hence the separate download. My iSight is not up to the task of capturing the whole room.
• I am frequently off-camera. I knew I moved around a lot ...
  
• The whiteboard scribblings are readable, but sometimes just barely so. I need bigger markers (wider), and I should write bigger.
• I still dislike how my voice sounds recorded, and I look like a dork with the headset on. It was easily the best way to record the audio, though.

I don't know if these videos will actually be useful or not. I can imagine after listening to me for two hours already, you would be loathe to sit through a rerun ... on the other hand, for homework solutions, or trying to remember what I said about something in particular, maybe.

Ideally: one would remix the video with the powerpoint slides I used, so both appear side-by-side, cut out the 'dead' spots, and add some indexes so you could find any particular spot in the lecture at will. Or: I could continue getting at least a few hours of sleep per night.

Better yet: check out the iTunes University. People with staff, resources, and pro technology are already doing this ...

Friday's quiz

The quiz tomorrow will only cover relativity (ch. 26 in Serway, ch. 2 in the notes), it will not cover any of today's new material on electric forces.

The quiz is entirely concept-based, and has no calculations whatsoever. Questions like "Are time intervals longer or shorter moving observers." and so forth. It should take something like 15 minutes.

The actual format of the quiz is still a surprise, however. Almost guaranteed to be a pleasant one.

Thursday, 10 July 08

I wasn't quite satisfied with what we've done with relativity so far, and so I will spend half an hour on it again tomorrow. We hit all the high points, but have not done enough example problems to bring it all together, IMHO.

After the first 30mins or so, we'll start electrostatics. By and large, students find this much less conceptually difficult than relativity. If it feels like you're being thrown in the deep end so far, you are! But relax: it will pay off in the end. Relativity will be useful to us very soon, I promise. Treat the first two days as painful but necessary background for later goodies.

Anyway: the plan is 30mins relativity (incl. homework problems), the balance goes to electrostatics.

Lab: some of you already emailed me a paper. Good work: for doing two sessions' work in one, you can skip the lab today. Sadly, this was a one-time event - we have no other two-session labs. If you did not finish the paper yet, 6pm tomorrow is zero-hour.

Printed notes: any luck at the SUPe store? Anyone want hard copies?

Random homework hints:

5) This is just velocity addition/subtraction in disguise. The rest is there to distract you. Just like on the MCAT, e.g.
10) Wikipedia is your friend. But ... don't be going on about light cones and such unless you can back it up. Keep it simple :-) I'm in a generous mood: let's say that 3/4 of a page is close enough.

Printed Coures Notes

I did not have any copies of the notes printed at the SUPe store for the summer semester, because for the last two semesters, hardly anyone bought them. On average, only about 25% of the class purchased the notes, the rest elected to print them on their own, or read them online-only. Since the hard copies did not seem popular, I did not have more printed.

However, the SUPe store today told me that some people were inquiring about printed copies. They do have a few copies left from the last time I had notes printed, and agreed to put them on the shelves right away. The printed version they have is not up to date, and lacks some material that has been added to the online notes (for instance, the relativity chapter is not in the printed notes, nor are most example problems). However, the electricity and magnetism chapters are fairly complete.

If you strongly prefer a hard copy, you can try to get one of the remaining copies. They run about $30.

If you would strongly prefer a hard copy of the up-to-date notes, or find the SUPe store has run out, and would be willing to pay, leave me a comment here. If there is enough interest, I will see what I can do ASAP (like by Friday, perhaps).

Lab procedure 9 July 2008

Today is our first real lab period. Exciting, isn't it?

The plan for Wed 9 July and Thurs 10 July is for you to spend 2 days in groups researching and writing a small paper about a recent scientific development. Here is the writeup [pdf]; print out one copy per group when you arrive for the lab (329 Gallalee, 3:30pm TODAY).

Basically, you will have to:

• find a recent scientific development covered in the popular media (online)
• assess its importance
• assess the quality of the article (do you buy it? is it really a big deal?)
• relate it to physics/chemistry/biology courses you have taken
• relate it to your field of study

The thing is only supposed to be two pages long, so I think you can come up with something nice in two lab periods. Beware, however, that group writing is not always easier than going it alone: you will have to be organized and efficient.

And, yes, grade-wise this will count as two labs.

Course Intro & First Homework

Welcome to PH102! At the bottom of this page, you will find our course calendar, which you should review carefully. We will stick to our schedule rigidly, as our time is quite short over the summer semester.

You may also want to look over the course syllabus and other information, which you can find here. The slides I'll present in lecture today are here, which also includes all of the important syllabus-type information.

Finally, your first homework set is already due next Monday, 14 July 2008. Have a look.

See you at 10am ...

Multiple choice portion of final

I have preliminary grades for the MC section ... I will have to go back and double check everything this weekend, but to give you an idea of how it went:


The plot above is the distribution of scores. No one aced it, the closest was missing only 1 of 18. Congrats to Mr. Mgbemena.


The plot above is the percentage of you answering each question correctly. Obviously, questions 2 and 14 just sucked. As did 18, a little bit. Otherwise, not bad. Those three questions basically account for the relatively low average.

The average on the MC part was 71.6%, with a standard deviation of 14.3%. There will probably be a slight curve, amounting to about 5 points.

FYI, the multiple choice and problems sections will be curved separately (if necessary) - if the average on the problems ends up very low, it will be scaled more. The separately scaled scores will then be added together for the final grade.

You can start inquiring about grades on Monday, I will be done grading exams by then.

Final solutions

Or, at least the multiple choice section. Re-read the homework and quiz solutions, and you will find many of the solutions to the problems section.

Exam II solutions

Here you go, for the last-minute cramming.

Homework 12 solutions

Here they are, almost complete. Only the one about the ring of charge is not yet complete, but I assure you that particular problem will not show up on the final exam.

For more last-minute fun, here's a draft of the formula sheets I'll be including on the final. This is not final, has not been proofread, etc., but gives you an idea of what to expect.

Also: relax. If you've been going to class and following the homework/quiz solutions, you have nothing to worry about. Most important will be to keep your cool and use your time wisely on the final - don't get stuck on any one question for too long, and don't panic.

Correlation between homework and pre-final grades

This isn't particularly shocking, but there is a 87% correlation between your homework average grade and your up-to-the-minute overall grade.

There is not a lot of hidden meaning here: if you did your homework, and did it well, you scored well on everything else by and large. We can say with (much) better than 99.95% confidence that your homework score is a good predictor of your total grade. This establishes correlation but not causation, though in this case I would hazard a guess that doing your homework in fact causes you to do well on everything else.

My current theory is that the final exam scores will follow this plot as well, supposing that it is a bit late to catch up on everything at this point. I am hoping, though, that you prove me wrong!

Final exam format

FRIDAY 9 May, 8am-10:30am
329 Gallalee

As we discussed today, the final exam will consist of two parts:

Part I: Multiple choice. Worth 50% of the exam grade, approximately 20 questions. Roughly half will be conceptual, roughly half involving simple calculations. Solve them all.

Part II: Problems. Worth 50% of the exam grade, you will solve a certain number of problems in each of 7 sections, for a total of 11 problems. You must solve the indicated number of problems in each section.

• Electric forces, fields, and energy: solve 2 of 5.
• Current, resistance, and dc circuits: solve 2 of 4.
• Magnetism & induction: solve 2 of 4.
• ac Circuits & EM waves: solve 1 of 3.
• Optics: solve 2 of 4.
• Relativity: solve 1 of 3.
• "Modern" Physics: solve 1 of 3.

You are allowed two full sheets of standard 8.5x11" paper, front and back, with formulas and so forth. I will provide most formulas and all numerical constants (masses, etc.) on the exam. Beyond your formula sheets, you are allowed only writing implements and a calculator.

The final is worth 20% of your total grade.

Post any questions you might have here, so I can easily answer them for everyone.

Special topics lecture next tuesday

On Tuesday 28 April, we have a "special topics" lecture scheduled. If you can suggest anything - related to the ph102 material, at least tangentially - that you might be interested in hearing about, let me know before the end of the weekend.

If there are several topics I think I can work up on short notice, I'll pick the one I think has the most broad appeal. If no one suggests anything, I will talk about what it is I do.

Other possibilities:

• how does MRI/PET/CAT work?
• how does your iPod work? (related to what I do)
  
• more bad movie physics
• how do semiconductor devices (transistors/flash/whatever) work?
• length scales, from nuclei to galaxies
• something you think I did a poor job explaining the first time around :-)

Leave a comment here (or email me) to vote on one of these, or suggest another topic.

And no, it won't be on the final. This one is supposed to be purely curiosity-driven, "for fun."

Lab for Thursday 24 April

Today, we will put the Bohr model of the atom into practice, and measure the atomic emission spectra from Mercury and Hydrogen.

April is stress management month

From the CW:

"April is stress management month," said Jennifer Turner, coordinator of clinical services for the Counseling Center.

Why am I just finding out about this now? Probably my technique of "more coffee and less sleep" would be frowned upon ...

Homework 11 solutions

Find them here ... enjoy.

I will try to get solutions to exam II out soon as well.

Final Exam

You may have noticed that our final is

FRIDAY 9 May, 8am-10:30am
329 Gallalee

It is very early, and on Friday. I dislike this too, but we are stuck with it. I will bring donuts or something.

This is it, the last homework set.

Here you go. Mostly, it is review, with a couple of problems thrown in from the atomic and nuclear physics we will cover this week ... just so that isn't a surprise on the final. In fact, this will serve as a good review for the final. I will go over these during Saturday's review session, as well as during class this week.

The homework is officially due this Friday, in observance of dead week, but I will not assign any late penalties for this homework so long as it is turned in before 5pm on the last day of classes. Read that any way you like.

There will be no new assignments or graded work during dead week. We will only cover "special topics" not on the final, and review for the final.

So, basically, besides one more lab and one more quiz, this is it.

Final Exam Review

Next Saturday (26 April), I will offer a final exam review session, from 3:30-6pm in Shelby 107. Note the non-standard day, time, room, and building.

I will be around during that whole period to answer questions and review material, you can come and go as you please - it is not really intended that you stay the whole time. I will prepare some example problems to work through, come with your own specific questions and I will try to answer them.

Also, there will probably be video games.

Lab for Thurs 17 April

Today, we will measure Planck's constant.

Open source textbooks in the news

I'm not the only crazy one. Best quote:

“The world doesn’t need another linear algebra textbook on the market — it needs a free one.” - Rob Beezer, a professor of math and computer science at the University of Puget Sound.

Pretty much how I feel about the situation.

MCAT is impending ...

So. I hear many of you have a big nasty test coming up.

Come with sample MCAT problems (ideally with solutions as well, if you have them) and I will solve a few in class on Thursday. I'll bring a couple of my own.

Otherwise, the agenda for Thursday is to solve quantum & atomic physics problems, i.e., the homework set posted yesterday. I think in this case it is easier to understand by just working through some "practical" examples, rather than pontificating too long on how weird it all is ...

After all that, we will measure Planck's constant. Exciting, huh?

This one goes to 11.

Your next homework is out. We'll do plenty of these in class during the week.

Lab and content for Thurs 10 April

Here is a lab for today's class, a last bit of optics before we move on.

Our next topic will be quantum physics. I do not, as yet, have notes for this topic. Don't fear: if you've had a chemistry course or two, I doubt you will need any. I'll discuss this more in class.

After about a week of quantum physics, we are on to atomic physics, and finally we will end with nuclear physics. Time flies, we are nearly done.

Exam II scores and distribution.

Well, well, you are more clever than I thought you were :-)

The class average - including the bonus question - was 88.0%, with a standard deviation of 11.7.

Without the bonus question, those numbers are 83.6% and 11.3, respectively. I consider this to be a better measure of how you all did (the bonus question is just free points, basically). Well done, many of you raised your grade significantly. The bonus point, on average, added 2.7 points to your score ... for what basically required you to remember a demo I did in class, or read the notes.

Here are some pretty plots to tide you over until I pass back your individual exams ... tomorrow in class. Click for a larger image.


Some comments: numbers 4 and 8 were not popular, nor were the scores very high. For the former, I blame this on not covering the quantitative aspects of filters enough. For the latter ... it was simply a tricky problem. Number 2 also had a slightly lower average. Much of that was due to not realizing you had to add the field from both wires (HINT for homework), but the problem did involve several different steps.

Sources of some of the problems:

2 - related to examples in the notes, loosely
3 - nearly identical to example in the notes, ch. 7
4 - essentially identical to a HW 8 #2
5 - you hadn't seen an LC filter before ... good work.
6 - related to HW 9 and notes problems
7 - just geometry, nothing more
8 - a question on the first lenses lab ...

Homework 10

Here is the exam you took today.

Your homework, due Mon 14 April at 5pm, is to solve the two problems you did not attempt on the exam.

Exam II is imminent

After finishing proofreading the exam and making a formula sheet, I quickly took the exam myself. Solving the exam, fixing typos/errors, and checking that the formula sheet had everything you needed took me 32 minutes.

I expect you can do the exam in an hour if you don't need to use the formula sheet, since you only have to do 75% of the problems, and don't have to proofread per se ...

I think you are well prepared for the exam. Read all the problems first, and choose your 6 wisely. Solve the ones you really know the best first, and work your way down. Time management is crucial, so don't get stuck anywhere - carefully read all the problems first, it will save you time in the end. There will be heavy partial credit, like on the homework, so show all your work - demonstrating you know what you are doing even with a numerically wrong answer is worth a lot of points.

And, for the night owls (or early risers I suppose), your formula sheet is here. You're better off reading homework solutions at this late hour though.

HW 9 solutions

So far I only have solutions for the first two problems. Over the next hours I will be updating the solutions ... hopefully all or most of them will be posted by 10pm.

Here is what I have so far. Check it every hour or so starting at 8pm ... I'll update this post when they are complete.

Exam-wise: study the quiz and homework solutions, and you will be fine.
-------------
UPDATE 10pm: rough solutions are finished for 1-3, 7-9. I have to finish writing the exam now, so problems 4-6 will have to wait until at least 11:30 ...

Office Hours Monday, misc.

I'll be in my office from 11-2 on Monday for exam-related questions ...

Also, this is interesting ... a lawsuit claiming that students' notes infringe on the professor's copyright. I will not comment directly, there is subtlety involved in this case ...

For the record, my notes are under an open content license. Basically, you can distribute them in whole or in part in any medium you like, without changes. That is, libre, not merely gratis, or free as in "free speech," not "free beer." If you modify the notes, or want to make them into a book, you do need my permission. I doubt you'll break the bank selling them, since they are free online though ...

Tangentially related anecdote follows, with little relation to ph102 ...

I published my Ph.D. thesis under a similar license. I had written several chapters which I though were a good review of my field at the time, and though the best thing would be to make it freely available to anyone who could use it. At the time I felt very strongly that information should be free whenever possible, without creating real or artificial barriers for those who genuinely want to learn something. If your hard work can benefit someone else, that is reason enough to do it. I still feel that way, and that is why nearly everything we do in ph102 is online, for free. When I get to it, anyway.

In my thesis (and in the notes, for that matter), I even carefully remade every figure myself to avoid using any copyrighted material whatsoever- since I had such a hard time finding figures I could freely use, why not save someone else the trouble down the road. It can be tough to find nice explanatory figures for basic things that aren't the Intellectual Property of someone or another. My aim was subversion: if I have to make my own figures anyway, give them away for free, so no one else has to go through the trouble. "Information wants to be free," so the saying goes.

So, a few months after my Ph.D. or so, I was in a conference listening to a talk, and about three slides in was one of my figures in the introduction. Six months later or so, a colleague asked me to help him write a review article. Guess where a good number of the figures came from! This was some years ago, so and things have become outdated a bit, but still every now and again at a conference, I do a double-take, and realize I'm looking at my own pictures ...

That is probably the most satisfying feeling I've had as a scientist thusfar. And that is the idea behind the notes. You're already paying to listen to me - and paying well - there is no reason you should pay a second time, or pay to share what you've learned when you leave here.

On that note, I still have quite some editing to do ...

* Paper and ink still costs money of course. Hats off the the SUPe store, who did a brilliant job, and went out of their way to keep your cost at a bare minimum.
** This post is obviously my own viewpoint, and not that of UA. Disclaimer applies.

Homework 8 solutions

At long last, the homework 8 solutions are out. Homework 9 solutions and additional problems on lenses are forthcoming ...

Also, since you are dying to know: below is the breakdown of scores by question for the last two homework sets. Click for a larger image.

Preemptiveness

Thursday, there will be no lab. Before you become unreasonably distraught, let me explain our alternative plan.

The plan is the following: we finish the lenses material and solve some problems for the first 45 minutes. What we have left is basically to pull together all of the arcane geometry we have used so far and put it into practice - as you did in the lab yesterday. I wasn't joking, we really have done all the math we need for every lens problem you will encounter, the rest is just artwork. Thus, a lot of the first half of class will involve practical examples rather than geometrical proofs.

And then, during the second half of class, there is the preemptiveness. The second half of the class will be entirely devoted to exam II review. Come ready with any and all questions, and I will attempt to answer them for about an hour.

If you don't come with questions, I will invent my own and answer those ... which is usually far less interesting from your point of view.

Office hours for Wed 2 April

I have double booked myself a little bit tomorrow ... I have a short meeting from 11:00-11:30, but will be available from 11:30 onward tomorrow for homework questions.

Exam II details

Exam II, as it turns out, is coming up next week - Tuesday, 8 April 2008.

This exam will have no multiple choice questions, it will be entirely problem-based. You will be presented with 8 problems, of which you can choose to solve any 6. You may attempt all 8 problems, but will be graded only on the six that you choose. The topics covered will be magnetism through lenses, thus the following:

• Magnetism
• Induction
• ac Circuits and EM Waves
• Reflection and Refraction
• Mirrors
• Lenses

Additionally, it is likely that there will be one bonus question, worth some to-be-determined fraction of a full question.

Now, consider this: there are six topics, and eight questions. Probability dictates that I will have on average 0.75 questions per topic. Out of your six chosen questions, you are thus likely to encounter 4.5 of the six topics, depending on your choices. Playing the odds, then, one would expect that at least one of the topics above could be safely neglected in preparing for the exam without issue, provided one knew the other five topics sufficiently well.

In other words, you may be better off knowing five of these things very well than six things not so well.

Like last time, you may bring in two sides of an 8.5x11 inch sheet of paper (one sheet front & back, or two sheets front only) with anything you like on them. Those sheet(s) plus a writing implement and calculator are all that you may bring. The exam will take place during the normal class time in the normal place. After answering your last-minute questions, you will have 90 minutes for the exam (though I expect it to take only 60 minutes on average).

More details will follow during the week. Your safest bet is to study the quiz and homework solutions, as well as the example problems in the notes - the exam questions will be easier than the homework (by far), but harder than the quizzes. The solutions to homeworks 8 and 9 will be out by Thursday.

Preliminary lenses notes

The lenses notes are not quite yet complete ... but I hope to have something more or less finished by class time on Thursday.

Right now, I have a derivation of the image properties of spherical and flat refracting surfaces, and the basic equations for spherical lenses. By Thursday, the rest of the material should be there along with some practice problems.

You can find what I have completed here.

Lab for 1 April 08

Here you go. We will investigate various lenses.

HW 9 due date MOVED to Wed 2 April

Well. Since we have no new homework set next week (due to an impending exam the following week), there is no good reason to make the homework due on Monday. The 9th homework set is now due Wednesday, 2 April at 5pm.

The idea is, of course, to make sure after Wednesday that you have nothing in your way to prevent you from studying for the exam ... the details of which will follow in the coming days.

Small update to mirrors notes

I added a bit at the end of Ch. 11 about parabolic mirrors, and fixed some nagging typos. You can download a revised set of notes on mirrors here. The linked file contains only the chapter on mirrors.

I hope to have something on lenses posted by the end of tomorrow. By the end of Friday's recitation we will cover enough of the material on lenses for you to complete the homework.

We will spend quite some time on the homework in class Thursday.

Lab procedure 25 Mar 08

Today we will explore reflection and refraction of light. The procedure is very open-ended, intended to be discovery-based.

Here is the procedure, read it through before starting.

Homework 9 is out

Fun with optics. Enjoy.

UPDATE: Problem #9 has been changed. As stated, it was more difficult than I thought ...

Submitting your papers

Some of you will choose to submit your papers electronically - which is fine. I have no problem accepting papers by email, it is actually far more convenient. However, make it easier on me, if you would:

1. Include your last name in the filename somewhere, preferably first.
2. Include 'ph102' in the filename.
3. Remember that I will have >50 papers in the end ...

For example, "smith_ph102.pdf" is good. I know which paper is which right away, alphabetical sorting will work, and I know this is related to ph102.

These silly little things help a lot in the end - having 55 files named 'physics-paper.pdf' or something similar is extremely frustrating.

How to write a physics paper

Physical Review Letters' editorial board tells you how to write a good 'letter.'

By 'letter,' of course they mean 'short paper suitable for a general physics audience,' not something of the 'Dear John' variety.

Of particular note: I am not alone in being deeply confused by scientists' love for the passive voice. From the article:

The issue of sentence-level construction is less critical, and it will not surprise me if some writers still take comfort in the passive-voice style described above. Frankly, this comfort is a mystery to me.

In all, the article is useful advice from one of the top physics journals around. And I'm not saying that just because we have the same initials.

Fun

http://xkcd.com/397/

No recitation on Friday 14 March ...

... I mean, let's be perfectly honest with ourselves.

Lab for Thursday 13 March 2008

Mutual inductance.

Make sure you read it through before starting the experiment, and follow each step carefully. It is straightforward in the end, but there are some preliminaries that must be taken care of first.

Homework 8 hints ...

I figure you want to get this out of the way before the break ...

Full-wave rectifiers:

http://hyperphysics.phy-astr.gsu.edu/Hbase/electronic/rectbr.html
http://www.eecs.tufts.edu/~dsculley/tutorial/diodes/diodes3.html
http://en.wikipedia.org/wiki/Diode_bridge

Diode protection:

http://www.coilgun.info/theory/inductivekickback.htm
The electronics bible

Audio crossover:

http://en.wikipedia.org/wiki/Audio_crossover

Filters:

http://www.play-hookey.com/ac_theory/lo_pass_filters.html

and links within. play-hookey.com is great for learning about practical circuits.

Inductive and capacitive coupling:

http://www.thinksrs.com/downloads/PDFs/ApplicationNotes/AboutLIAs.pdf

Look at page 7, you should recognize the figures. The rest is a bit hardcore, and not directly relevant. I think you might find the first page or two interesting, though, if you have time to kill. I'm happy to explain what a 'lock-in amplifier' is if you are curious ... I use them daily.

Using the internet to do your homework is fair game, copying verbatim is not. Restate things in your own words, at the least. I picked the problems for a reason, namely, that I think they illustrate important concepts that you will find useful at some point. [1]

[1] For example, an MRI magnet is a giant inductive load, hence problem 10. Understanding audio electronics is nice, hence problems 1,2, 7-9. Problem 3 is something you put into practice every time you plug in your laptop or charge your ipod. Etc.

Lab for Tuesday 11 March

Today, we will investigate current and voltage in ac circuits.

Enjoy. Print one per group, that is enough. Note that you do not need to print any plots for this lab.

Homework 6 solutions

Finally, they are out. Excepting problems 9 and 10, which I did in class anyway.

Homework 8 is out

Here you go. Note that this is due the day after spring break. We will try to do plenty of these in class on Thursday ... most of them are qualitative, and do not require any calculation at all.

Lecture by Nobel Laureate Albert Fert

The 2007 Nobel laureate Albert Fert will be giving a public lecture tomorrow 7 March, at 1:30pm in Gallalee 227.

He will be talking about the present and future of "spintronics," electronics which relies on magnetically and electrically manipulating the spin of electrons rather than their charge for added functionality. Such stuff is in your hard disk, right now ...

The lecture is slated to last until 3pm, and there are refreshments afterwards ... not to often you get to see a Nobel prize winner, I encourage you to take the opportunity if you have time.

Homework 7 is out ...

... and here it is.

I hope to have homework 6 solutions posted by midweek.

Lab for Tuesday, 4 Mar 08

Today we will investigate induction. This lab should not be quite so painful as the last one.

Playing for the wrong team?

Perhaps, but this was too cool to pass up. The top 10 Amazing Chemistry videos, courtesy Wired. You should probably ask about these things in your chemistry classes. I, of course, know nothing about any of these. Particularly number 8.

The usual disclaimers apply. Don't try this at home, or anywhere on campus.

Paper topics

Paper topics are due tomorrow. What I want from you is a 1-2 sentence description of what your topic is, ideally with a preliminary source.

Full paper details are here, scroll down to page 9.

Midterm grades

Your midterm grades have been uploaded to myBama. A few points to consider:

I have not dropped any labs or quizzes yet. Therefore, if your grade is a bit lower than expected, and you have missed labs or quizzes so far, this might be it. Consider the midterm a worst-case scenario.

I have not used pluses or minuses for midterm grades, but I will for the final grades.

Finally, there is a lot of time left. Midterm grades are only a guideline, it is fairly easy at this point to change your grade (in either direction) by even a whole letter grade. Don't panic!

Tomorrow in class you will receive a grade report, broken down by category, to let you know how you are doing so far.

PAPER TOPICS

Reminder:

Your paper topics are due by Friday. I need a trackable source (email/facebook notification is fine) - reference, URL, etc.

Additional note:

I will post midterm grades Wednesday morning for all students. For midterm grades, I will drop 1 quiz grade and 1 lab grade. Inquire tomorrow during the lab period or after class if you would like a heads-up.

Lab for Tues 26 Feb 2008

Today's lab may be a bit more lengthy than usual. There are many steps to follow, and it uses nearly everything you have learned so far.

Here you go.

Print one copy per group, and read it carefully before you start. Be sure you understand the idea of the experiment before you get started ... it will save you time in the end. Don't hesitate to ask if something is unclear.

Homework 6

Here you go. Mostly magnetism, a couple of induction questions. Due Monday, 3 March at 17:00.

Enjoy.

UPDATE:

My bad, uploaded the wrong file. It should be fixed now.

Stupid professor question.

Sadly, I am no longer 'with it.' Were I to have an instant messaging account for this class - e.g., so I can answer homework questions in real time - what sort of internets are you using these days? A particular facebook chat application? AIM? Google chat? Since it is no longer 1992, I fear IRC is no longer cool.

Give me some ideas in the comments. I would like to have something more interactive for answering your questions that allows an actual 'conversation' in real time, but I think it only makes sense if it is a system many of you are already using. So, what is your favored online chat client/system?

Exam I results

Well, the results are in. Apparently, you are more clever than anticipated :-)

The overall average was 80.75, with a standard deviation of 15.11, which I was very happy with. Four people answered all questions correctly, well done. Here is the histogram:



Keep in mind that one question is worth 5% (there were 20 questions), so it is somewhat expected that the 'spread' is a bit wide. An average of about 80 means missing only 4 questions. As you can see below, three questions in particular were on average more difficult:


Questions 4, 11, and 12 were most difficult, and I find this somewhat reasonable: question 4 required a subtle application of Gauss' law, and with question 12 it was easy to either misinterpret the question or misapply the power formula. I expected both of these to be harder.

Question 16, another difficult one on average, was basically dimensional analysis in disguise, but nonetheless quite tricky. Question 18 is probably lower due to our covering RC circuits very quickly. Again, I am not surprised that these two seemed more difficult.

Question 11 was, you may now realize, distilled from problem set 4 question 9. It was a difficult question, but one you had the solution to in advance. I did expect it to have a lower average, perhaps not quite as low as it was though.

One very good point: question 17 was right off of the last quiz. On the quiz, only 13% of you answered correctly, compared to 92% on the exam. This is what we like to see!

Anyway: early next week exam solutions will be posted, along with analysis comparing each exam question to a previous similar question from the problem sets or quizzes.

A little bonus for the night owls.

This is the formula sheet you will get tomorrow. If you are still busy making one, you don't need to include any of this.

Homework 5 solutions

Here you go.

Quiz 5 solution

The answers to quiz 5 are now posted in the usual place. For now, there are no detailed solutions. I will try to post those some time Tuesday (and we will go over the solutions in class).

By the way, here are the results:


Obviously question 1 caused some trouble, and we will go over it detail. Note that question 3 was directly from last week's homework, while questions 4 and 5 were straight from the course notes. The solutions for all three of these were available in advance of the quiz.

Exam I details

Exam I is, as you know, scheduled for this Thursday, 21 February. This means that there is no homework due this week, and no Friday quiz. Perhaps the most notable thing about the exam is that relativity is not included.

The exam will cover the following sections in the Serway & Faughn book:

Chapter 15, including Sections 1-6, 9
Chapter 16, including Sections 1-4, 6-10
Chapter 17, including Sections 1-5, 8
Chapter 18, including Sections 1-5

If you are paying more attention to the course notes, it covers the following (referring to the online version):

Chapter 3, excluding Sections 3.6, 3.7
Chapter 4, excluding Sections 4.7, 4.2.2.1
Chapter 5, excluding Sections 5.4.1.1, 5.4.6
Chapter 6 ALL

Whether you pay more attention to the book or the course notes, the list above covers the same topics.

The exam will be multiple choice, and roughly 25 questions long. I suggest studying the end of chapter questions in the notes, as well as your homework and quiz solutions to date.

Roughly half the questions will be conceptual or qualitative (no calculations), and roughly half the questions will involve real, live quantitative answers. With units and everything.

The exam will be in the usual classroom, at the usual time. I will devote the first 15-30 mins of class to answering last-minute questions, after which you will have about 90 minutes for the exam. I expect the exam to take you closer to 60 minutes, but don't want anyone to feel too rushed.

You will want a calculator for the exam.

You can bring in ONE standard 8.5x11 inch sheet of paper front and back (or two sheets front-only), containing any information you like. This could include pictures, formulas, example problems, or even the first few chapters of "The Count of Monte Cristo" in a very small font. Whatever you think might help. You can use both the front and back, typed or written, crayon or pencil, your preference.

One interesting variant is to write from left to right with a red pen, and then turn the page 90 degrees and write over the top of that with a blue pen. If you can then lay your hands on a set of 3-D glasses ... presto, you've doubled your storage density.

Homework 5 problem 6

I inadvertently made number 6b a bit harder than I thought ...

For part b, if you are not able to prove the general result, it is sufficient to prove that a parallel combination has lower power consumption than a series combination. Full points if you can do this, five bonus points if you solve the question as asked.

If you want to prove the general result as the question asks, see HERE for a massive hint, along with smaller ones for other questions.

HW 4 results

Overall, I was very pleased with homework 4. The average was 91.4% (std. dev. 8.2%), and most questions had an average of 90% or better:


Questions 2 and 8 caused some trouble though. Question 2 was difficult, I think, due to the unusual phrasing of the problem. This was intentional - you were given realistic data that one could easily measure, and asked to deduce something you can't easily measure. It is a conceptually tricky problem, I think it may be worth your time to read through the solution to this one.

Question 8 was also conceptually tricky. Definitely have a look at the solutions for this one. Briefly:

a) Charge carrier density in a metal is determined mainly just by how many atoms per unit volume there are. Each atom contributes a certain number of mobile electrons, like in problem 4.

b) Current density is just current per unit area - if one doubles, so does the other

c) Drift velocity is proportional to current and the electric field, if current doubles, so does drift velocity.

d) The collision time was assumed to be a constant for each material because it is primarily determined by the random thermal velocity, not the drift velocity. Chaotic thermal motion which gives no net displacement dominates the carrier motion, drift velocity is a tiny effect that gives a small net motion in one direction. In our simple model, collision time depends only on temperature and materials properties.

Out of town Thurs-Sun

As I mentioned today, I'm out of town from Thursday morning (14th) until some time Sunday night (17th). Thursday you will do a lab with Mr. Hamner, and Friday a quiz + exam review.

I'll be around my office most of the day tomorrow, and most of this coming Monday though (18th).

Keep in mind that homework is due this coming Monday, 18 Feb.

Lab for Thursday 14 Feb

We will investigate charging and discharging of RC circuits on Thursday. There will be no lecture, only the laboratory experiment. Thus, you should be done early ...

Here is the procedure.


Friday's quiz will be on dc circuits.

Nascar Physics

If one were interested in NASCAR, and had a physics paper to write, this might be interesting.

NY Times, free registration required.

[Reminder: paper topics are due Feb 29th.]

Homework 4 solutions

Enjoy.

I have not carefully proofread these yet, but all of the answers should at least be correct. I will post here if I find any major errors.

Lab procedure 12 Feb 08

As usual, download and print one per group.

Homework 5 is out

Here you go.

Solutions to homework 4 should be finished and online some time tomorrow.

Quiz 4 and its solution ...

here you go.

Corrections to HW 4

Typo on the first problem: you are supposed to find out how much money the user of the CF bulb saves, not how much energy.

Homework 3 solutions

Find them here.

UPDATE 7 Feb 08: Here are the results:


I can draw a couple of conclusions from this plot (and the massive amounts of grading it entailed). Before that: very well done! The overall average (87.7%) was honestly much higher than I was expecting on what was a fairly punishing problem set.

First, while finding an equivalent capacitance didn't cause much trouble, working backwards to get the charge and voltage on each capacitor was very tough for you collectively. We should probably work some more of those problems.

Second, on the first question many of you ran into trouble by using the wrong distances and charges setting up the problem. It is important that you read the solutions to the homework - all of the information you needed was in the HW2 solution!

Third, on the last question many of you calculated the potential energy of the system of charges, rather than the electric potential at the center of the arrangement. This, combined with question 1 leads me to believe I have not made careful enough distinction between electric potential and potential energy.

Finally, number 7 seems to have caused trouble for two reasons: first, mathematical difficulties , and second, not taking into account that the capacitor was held at a fixed voltage. I don't think there are serious conceptual difficulties here as a whole.

Lab procedure 5 Feb 08

This one should take 45 minutes or so.

Read this first (no need to print).

Here is the procedure.

Homework 4 is out

You can find it here. It is due one week from today, 11 Feb 2008, at 5pm.

Ten problems worth anywhere from 5-15 points each. Numbers 5 and 10 have silly tricks based on symmetry - you shouldn't find yourself doing a lot of math. Said tricks will be covered in class, to an extent.

I would guess that numbers 3, 4, and 9 will seem more 'difficult' compared to the others.

Pentagons

In case you need some help getting the angles right, see this.

I misspoke in class earlier this week when I said the outer angles are 72 degrees. The inside angles when drawing lines from the center to each vertex are 72 degrees, the outer angles are 108 degrees.

Homework 2 results

Just because I know that you are all dying to know ... here is the breakdown for homework 2, average score by question and overall. You'll get your homework back in recitation.
So first: you are really good! The average was 96% overall, very well done on a difficult homework set. Keep it up.

The lower average on #2 does indicate to me that Gauss' law is still tough ... which is understandable. It is hard to get your head around at first, and it is something collectively we need to spend more time on, ideally.

The slightly lower score on question 1 is probably at least in part due to the fact that it was sort of an oddball conceptual question. Once you hear the explanation once, it makes total sense and you'll never forget. Coming up with it on your own is sometimes another story with questions like #1.

Monday is the new Friday

From now on, Homeworks will come out on Monday, and be due the following Monday.

This is being done so that we have covered all of the material well in advance of the due date. Homework coming out on Monday will cover that week's material, giving you the whole week + weekend to work through it.

Homework 3 deadline EXTENDED

Since we didn't get far enough on Tuesday this week, I have extended the deadline for this week's homework to Monday, 4 Feb. at 5pm.

Another reminder: the quiz tomorrow is just an assessment ... so you don't need to study for anything. We just want to know how much you know about electricity and circuits going in to the class so we can see how much you learned over the semester.

Corrections to Notes Ch. 4

I found some bad typos in sections 4.2.1 and 4.2.2 (energy of point charges and systems of charges) which have now been corrected. If you have already printed these or have the bound version, you may want to compare ...

You can download chapter 4 only here.

Public Telescope Viewing 31 Jan 08

As it turns out, we have a large telescope on the roof of Gallalee hall. Want to see how it works? Tomorrow night is your chance ...

The Department of Physics and Astronomy will host a public sky viewing of Mars and the Comet Tuttle tomorrow, January 31, beginning at 7 p.m. at Gallalee Hall. The event, hosted by Dr. Gene Byrd, is contingent on weather and sky conditions.

Lab procedure 31 Jan 2008

Tomorrow, we will do a lab to verify the equivalent capacitance for series and parallel capacitors. Please read the procedure here, and print one copy per group.