Monday, August 10, 2009

Grades / eLearning

All grades are now on eLearning.

There is one column for your final exam score ("Final Exam"), one for your overall average ("FINAL GRADE") and one column for your overall letter grade ("Final Letter"). All drop grades are included in the final score. Extra credit has been included in calculating the final letter grade, but may not be reflected in your final percentage score.

For the final exam, rather than scaling by a fixed amount, I used the best 5 problems that you did instead of 6. This put the final exam average at about 82%. Very few of you changed by a full +/- letter grade as a result of the final exam.

I will post grades to myBama tonight. Let me know if anything seems suspicious.

Wednesday, August 5, 2009

Yet more

RE: the last quiz, second problem.

You have only 3 possible energy levels. Photons can only be emitted when you have an electron changing from a higher level to a lower one. Here we have

E1 = 1.2eV
E2 = 2.4eV
E3 = 4.8eV

The only photons that can be emitted must correspond to differences between energy levels:

E3-E2 = 2.4eV
E2-E1 = 1.2eV
E3-E1 = 3.6eV

So three types of photons can be emitted: when an electron jumps from level 3 to 2, from 2 to 1, or from 3 to 1. Given these energies, convert to joules:

E=(2.4eV)(1.6e-19 J/eV) = 3.84e-19 J

Once you have that, use E = hc/(wavelength) and solve for wavelength. You should get about 1e-6, 5.17e-7, and 3.44e-7 meters.

Another question

Could you direct me (like HW so and so) to an example of the kind of refraction problem I should be looking at? They range from easy to REALLY hard and I don't know. HELP.
Study problems more like the easier ones - the quiz 9 problems, for example. Not the pathological ones like atmospheric refraction or prisms.

A couple of other examples that are useful to look at:

PH102 Fall 2007, Exam 2, problems #9 & 10
PH102 Fall 2007 Final, problem #9
PH102 Spring 2008 Exam 2 #6 & #7

If you understand these problems, you basically have things under control.

Collected questions so far this evening.

So far, two questions this evening. Here they are, along with my responses. If I get any more interesting questions by email this evening, I'll try to post the answers here for all to see.

1. Quick question on #7 from fall 2007 final: In part b do you use the E=mc^2 equation?
On #7 you do want to use E=mc^2 - I reused this question on a homework from Spring 2008 (HW12, here). The result is as silly as you would expect - half of the mass of the bullet would have to be turned directly into energy for this to work, which can't be done with any known technology.
2. An FM radio transmitter has a power output of 130kW and operates at a frequency of 98.3MHz. How many photons per second does the transmitter emit?

This is one like the HW question, where you need to convert power and energy. In fact, it is from spring 2008 HW11, here.

First, 130kW means 130e3=1.3e5 Joules per second, since a watt is a joule per second.

The frequency 98.3Mhz means 98.3e6 Hz. If the transmitter has this frequency, than means each photon emitted has an energy of

E = hf = (6.6e-34 J*sec)*(98.3e6 sec^-1) = 6.5e-26 Joules (per photon)

So, if the transmitter puts out 1.3e5 joules per second, and each photon is worth 6.25e-26 joules, that means the transmitter must put out

# photons = (1.3e5 J/sec) / (6.5e-26 J/photon) = 2e30 photons per second.

Basically, find the total energy being emitted per second (just the power given) and divide by how much energy a single photon has to figure out how many photons per second must be coming out. In this case, the intermediate step of converting to electron volts isn't really necessary - the power and energy per photon both need to have the same units, so you can convert to eV or just use Joules.

Exam II and a partial solution

Here. Answers for all problems, solutions for some.

Final Exam

So, I've made it up now, and I estimate based on your past performance that most of you can finish it in 90 minutes or so. Some of you will finish in under 60 minutes, just barely. One update: you can choose 6 of 9 questions, not 6 of 8. One more choice than promised.

Here are some of my random thoughts on the final. It goes to 11.

(1) Relax. There is no reason to be more freaked out about this exam than any other, percentages and so forth notwithstanding. You should be less scared: broadening the scope of the material necessarily means that the difficulty level for any given problem goes down.

(2) There is only one way to study for this thing: read and solve problems. You will be given all of the required formulas, memorizing them will not help, nor will memorizing tricks or shortcuts. All problems will involve the systematic application of simple principles and simple relationships, there are no tricks. Cramming is not useful.

(3) Cut your losses on chapters you don't think you can master in the time remaining. There are only 6 problems you have to solve. Nailing 5 out of 6 can still get you a solid B without even attempting a 6th.

(4) Look at the Fall 2007 final exam and the second PH106 exam from Fall 2008 (only the parts without calculus).

(5) No problems I have asked you before will appear on the final. No problems directly from the notes will appear on the final. However, about half of the problems will seem eerily familiar.

(6) Relax. You will need to have your wits about you, the problems on the final will involve logically solving problems step-by-step using simple rules. They will not involve remembering an arcane phrase or formula buried in the text, nor will they have many convoluted twists and turns. Most of them involve only 1 or 2 steps.

(7) Run the numbers on your grade. The final is worth 25% of the total grade ... it can only change your overall grade by so much. Not as much as you think. I will scale the average on the final if necessary, such that it is at least 75% for the class. It is unlikely to be necessary.

(8) I like crystals and mass spectrometers, and quantization of angular momentum. Capacitors have been done to death.

(9) Study the homework solutions.

(10) Seriously, relax. Get some rest Wednesday night, you'll be better off well-rested.

(11) Answers to exam II will be posted soon. Full-blown solutions are probably beyond my grasp at this point, given that it is already nearly 3am.

The last lab

Our last lab will be the measurement of atomic light emission spectra. It will prove that, although the Bohr model of the atom is provably wrong, and a bit silly at times, there is some truth contained in it.

More to the point: it is better than anything classical we've come up with, so its a good start. That there are more sophisticated models doesn't change the fact that our simple model works for a few things, and nicely at that.

I will be at the lab starting about 3:30 or 3:40, at which time I will probably have a few additional hints about the final.

Tuesday, August 4, 2009

HW 8 Solutions

The key for the crossword puzzle is now up.

Answers for exam 2 will be up once I finish with some grading later tonight.

Traffic for this site


Nicely periodic. Can you spot the weekends without looking at the time axis?

Neat optical trick

Your brain interprets color in funny ways.

Last HW and extra credit

I'll accept them both through this Friday, 7 Aug.

Updated Grades

I have uploaded current grades to eLearning, which now include HW7. If I made changes to lab or exam grades last week, they should now appear.

If I made changes to your lab grades today (or promised to) they do not appear yet, but will show up in tomorrow's update.

Have a look and make sure that everything shows up correctly.

Monday, August 3, 2009

HW 9 is out

Here. You can turn it in at the start of the final exam.

Recall that 1eV = 1.6e-19 J for #3.

Sections covered on the final

The final will have about 8 problems, you will have to do about 6 of them. You will get a basic formula sheet as in previous exams, and you may bring 2 sheets front & back of your own.

The following sections from the textbook are fair game for the final (ref. 8th ed.)

15.1-6, 15.9; 16.1-4, 16.6-10; 17.1-6; 18.1-5; 19.1, 3-4, 6-9
20.1-4, 6-8; 21.1-3 (no rms), 7, 10-12; 22.1-5
23.1-6; 26.1-6; 27.1-2, 5-6; 28.1-3

The following sections will not be on the final

15.7,8; 16.5; 17.7,8; 18.6-8; 19.2,5,10
20.5; 21.4-6, 8,9,13; 22.6-7; 23.7
24, 25 all; 26.7; 27.3-4, 7-8; 28.4-7; 29 all

To start with, you will do well to study the example problem in the textbook, and after that probably the end of chapter problems in the course notes. More example problems will be posted tomorrow.

Lab for Mon 4 Aug 2009

We'll measure Planck's constant.

Sunday, August 2, 2009

I've got your extra credit right here

A small paper. You will need to watch a movie to complete the assignment; I'm sorry.

HW8 is out

Here you go. Have fun, it is due Monday 3 Aug by the end of the day.

Why, yes, it is a thinly-veiled attempt to get you to read the chapters ;-)

New internets

Here are the slides I used Friday to discuss wave behavior.

Also, the notes now have 3 (incomplete) chapters on optics
.

Saturday, August 1, 2009

Stuff

HW 8 is coming. It will take you about 30min. Seriously.

If you had grade changes on Friday that we talked about, they are in the spreadsheet, but not uploaded to eLearning yet. Should have them uploaded this evening.

Friday, July 31, 2009

Grades

eLearning is updated with all outstanding work, except HW7.

The "Cur. Avg." column now takes into account your dropped grades: 2 dropped labs, 1 dropped quiz*, and 1 dropped homework. This is now a realistic representation of your grade.

The final exam counts as 25% of your grade if you want to estimate what you need on the final to get a certain grade.

*Quiz 4 is dropped for everyone, unless it is higher than your lowest non-dropped grade (at which point it replaces the lowest non-dropped grade).

Exam II


You'll get them back tomorrow. Most of you will be very pleasantly surprised. Elearning grades will be updated tomorrow sometime I hope; there are still HW and quizzes that need to be graded as well.

FYI, hand grading really sucks, but is worth the effort.

Thursday, July 30, 2009

HW8

... will be due on Monday, not tomorrow. Details later.

[cough]

Check out problem 2 in section 2 and problem 2 in section 3. You will be rewarded if you do so.

Wednesday, July 29, 2009

Lab today

Labs today: 3 mini procedures

Reflection & refraction
Total internal reflection
Lenses

HW 7 solutions

Here.

Filter circuits

This site is generally a good electronics resource, and it has a nice set of pages on filters.

Quiz solutions

All quiz solutions are now available (along with the original quizzes). Right over here.

All homework solutions are also available, except for HW 7 that was due about 4 minutes ago. I should have that one posted around class time tomorrow, or at least a partial solution if nothing else.

Tuesday, July 28, 2009

HW7 Answers

#1: thickness ~3e-9 m; time constant about 1e-3 sec; resistivity ~ 4e7
#2: about 2.25mV
#3: 43.75A, 38W
#4: steady currents can't go through the capacitor, ac currents can ...

Quiz and homework solutions are being updated right now ... should be complete shortly. Will post again here when they are done.

Monday, July 27, 2009

Grades

Your latest grades are on eLearning; this includes everything except today's lab. The "Curr. Avg. (no drops)" column is a weighted average of all of your different grades, not including the drop grades you are allowed. As usual, consider it a worst-case scenario.

Please check carefully that everything that is supposed to appear actually does - occasionally, lab reports or homework sets are misplaced, and the sooner we know the better.

Some details regarding Thursday's impending exam will show up here later tonight ...

Also: if you have questions about any of your grades, or can't/wont use eLearning, you can ask me tomorrow and I'll give you a grade breakdown.

Today's quiz

That circuit from the quiz today is often called a diode snubber, or a flyback diode. Very handy protection circuits; one can do similar things with an RC circuit (or low-pass filter) to buffer out rapid changes in current/voltage in a circuit.

Anyway: I didn't just make it up.

Homework 7

A short HW7, due by the end of Tuesday 28 July 09.

Sunday, July 26, 2009

Mon 27 Jul 09

Tomorrow, a lab on ac circuits. There are things in the lab write-up we did not directly cover in lecture, so be sure to read the introduction ...

Lecture: we'll start EM waves and move in to reflection & refraction. There will be a short quiz on ac circuits, covering the material from this past Friday's lecture.

There will be a very short homework set due Tuesday evening, only 2-3 problems, which will appear Monday morning.

Friday, July 24, 2009

Thursday, July 23, 2009

Einstein on induction

Here's what Einstein had to say about magnetic induction:

Imagine a conducting loop moving relative to a magnet as seen by two different observers: one on the magnet the other on the loop. Both observers see the identical EMF generated in the coil using the flux form of Faraday's law, but explain the result using two different reasons. The observer on the magnet sees the magnet as stationary with an unchanging magnetic field, while the conducting loop moves. All of the charges within the loop move with the loop, and due to the B-field experience a sideways Lorentz force, which generates the EMF. On the other hand, an observer on the loop sees a changing magnetic field due to a moving magnet (relative to the loop's reference frame) and no Lorentz force (charges in the loop are not moving). This changing magnetic field means ΔB / Δ t ≠ 0, which creates an electric field that generates the current.

This is what I was trying, less eloquently, to explain this morning.

Quizlet tomorrow

A good hint would be to look at "Example 20.4" and "Applying Physics 20.2" in the text, the sliding bar problem (Motional EMF).

The notes also discuss the same basic problem, e.g., pg 174. Or, look at problems 6 & 7 here.

Whatever I come up with for the quiz will be related to launching metal bars off of conducting rails in some way. Possibly at enormous velocities.

Homework 5 solutions

Here you go.

dc/rc lab reports

If you picked up your graded dc/rc lab reports either today or yesterday: you picked them up off of a pile that was not meant for you (yet). I didn't have them recorded in the gradebook yet -- you grabbed them off of the pile the TAs left for me.

So. If you already have a dc/rc lab report, you'll want to bring it back to me right away ...

I never could get the hang of Thursdays.

Thursday, we'll do a lab on mutual inductance. That is, we'll build a small transformer. We'll cover the material relevant to this lab in Thursday morning's lecture on inductance.

Other things:

I hope to have all solutions (quiz, exam, homework) up to date by the weekend, I will try to put out at least an answer key for everything by Thursday afternoon.

In the lab (and probably the lecture too) we'll go over remaining questions on HW6, which is due by the end of Thursday.

We'll finish most of induction Thursday itself, and will probably only need 1 day for ac circuits. We might actually be ahead of schedule by the end of Monday. If this actually happens, I'll probably devote one day (or maybe a half day) next week to a 'special topics' lecture, e.g., how do hard disks/computer memories work. Other suggestions for a special topic? Drop a comment.

Wednesday, July 22, 2009

eLearning FAIL

Right. By default, eLearning chooses not to show you any new grades until I explicitly tell it to release them for student view. Basically, this means that my upload earlier today did not show up for you.

I think it is fixed now, and you should be able to see all of your grades.

Wednesday's lab

Today, we'll measure the earth's magnetic field.

Or, depending on how careful you are, perhaps you'll measure the remnant field of the ferrous I-beams in the building, or the steel leg holding up your table. :-)

NOAA gives you a way to check your answer. Beware, imminent data overload ...

Grades / eLearning

Just uploaded current grades into eLearning. This includes:

  • Quizzes 1-5*
  • Homework 1-4
  • Labs 1-4
  • Exam 1
  • Current average grade**
When you get a chance, make sure it looks right ...

* Quiz 4 was a 'free quiz' - dropped for free, unless you scored higher it than your lowest quiz score otherwise. In which case, Quiz 4 replaces what was previously your lowest grade ...
** This is a worst-case scenario - no dropped HW, Lab, or Quiz grades, excepting the case discussed in the previous footnote. Weighting of various components is according to the syllabus.

Tuesday, July 21, 2009

HW 6 is out

Right here. Not due until Thursday, we'll set most of them up in Wednesday's lecture & lab.

Monday, July 20, 2009

HW 4 solutions

Here you are.

Lab for Mon 20 Jul 09

Monday, we'll do a lab investigating series & parallel combinations of resistors and resistor-capacitor combinations.

Here's the procedure
.

Homework 5

Here you are, due Tuesday night. Relatively short ...

Sunday, July 19, 2009

HW 3 Solutions / Quiz 5

Here are solutions to HW3.

Tomorrow's short quiz will be on dc circuits, covering material from this past Friday. It won't be too bad.

Friday, July 17, 2009

HW4 hint

Check it.

UPDATE: on number 4, I get currents of 188.67A (live battery), 168.56 (starter), and 20.11A (dead battery). On number 1, I get 0.128 ohms.

UPDATE 2: numbers above corrected.

Thursday, July 16, 2009

Exam- & Grade-related items

First: I am dropping quiz 4. This is for your own good :-) It will not be entered in the grade book, but it did give you a preview of 4 of the 25 exam questions. The average was going to be such that most of you would have ended up dropping it anyway. More generally, this is why I dislike multiple-choice quizzes, and should stop giving them: with four questions, if one trips up most of you, the average is already going to be below 75% at best. I made them multiple choice this time just so they would be identical to the exam questions.

Anyway: the quiz served its purpose in my mind - you really nailed those four questions on the exam.

Second: the exam is graded, and your grades are on eLearning. There is also a new column which lists your current overall average grade. This does not include any dropped grades, and thus you may consider it a worst-case scenario at the moment.

Here are some more details on the exam grades:

The average was 75.3, standard deviation 13.5. This basically means it was not necessary to scale it, and it went better than you think (mostly). Here are a couple of histograms. The first is coarsely-binned at 10 points (roughly corresponding to A, B, C, etc), the second is more finely-grained at 4% increments (corresponding to +/- 1 question). (Click on pics for larger versions.) Looking at your average score per question is - for me anyway - far more insightful. This tells me which stuff I need to review a bit more before we get to the final.


We'll go over all the questions which averaged less than 70% or so in Friday's class.

Third: it is still far too early to freak out about grades. If you have been completing most of the homework and quizzes you are not in any trouble yet. Conversely: if you haven't done any homework ... now would be an awesome time to start. The average course grade right now is 85.4, a solid B.

Quizzes, homework, and labs will shore up one bad exam easily. Here are the class averages for various components:

Lab - 94.6
Quiz - 83.5
HW - 90.0
Exam 1 - 73.6

Clearly, the best plan is to do the homework and show up for the labs ... apparently these points are easier to get.

Fourth: Check your grades carefully to make sure nothing is missing. Sometimes, I forget to upload a homework score, etc.

Quiz 4

Here's the quiz you're taking right now. These questions will appear verbatim on this afternoon's exam.

Wednesday, July 15, 2009

HW 4

HW4 is ready. Due by the end of Friday. Five problems, but only three require any sort of calculation.

We'll go over most of the HW4 problems during Friday's lecture.

Wednesday's lab

You can find tomorrow's procedure here. Two documents: an introduction to the data acquisition hardware & software we'll use for the next several labs, and the procedure itself.

It should not take more than 60-90 minutes to do the actual lab. We'll devote about 30min at the start of the lab period to answering homework questions and discussing the exam.

Grades

I just uploaded more grades into eLearning. So far, we have:

Lab 1 (papers), Lab 2 (errors), Quizzes 1-3, Homework 1-2

If you are missing a homework 2 grade (or it just says zero, but you know you turned it in), that means I haven't gotten to yours yet. In particular, homework turned in to the TAs at the end of last lab session are not graded yet.

Tuesday, July 14, 2009

Quiz 3 from Fall 2007

Quiz 3 from Fall 2007 had an error in the solutions. This has also been fixed.

Please, do let me know if you find errors in any material, current or not. Even if it is not an error per se, but you think the explanation could be better, it is helpful feedback.

Quiz 3 and its solution ...

... are right here.

Due to a stray minus sign on the formula sheet, question 1 has been thrown out. I'll explain in class on Wednesday, but basically it means everyone gets credit for number 1.

Exam I details

Exam I is, as you know, scheduled for this coming Thursday, 16 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 Thursday 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:

  • Electric forces & fields
  • Electrical energy & capacitance
  • Current & Resistance
Basically, it will cover everything that we have done through the end of Wednesday's lecture, with the notable exception of relativity.

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 in the lecture room, Gallalee 227, but at the usual lab time of 3:00. We will devote the first 15 mins or so 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 of your sheet, 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.

The plan for Tues, roughly

Basically, we'll finish up electrical energy & capacitance.

  • More details about the exam ...
  • Review HW2 problems
  • Review of electric potential - relation to PE and work; point charges
  • Systems of charges - potential energy and stability of crystals
  • Isolated conductors and equipotential surfaces
  • Review of capacitor basics - adding in series & parallel; parallel plate capacitors
  • Complex capacitor combinations - how to analyze
  • Capacitors with stuff inside - dielectrics & dipoles in electric fields

HW 3 / HW 2 solutions

I know you're dying to start the next homework. Due by the end of Wednesday, we'll set up a couple of them in class tomorrow. There are no vectors involved in this problem set :-)

Also, here is a draft of the HW2 solutions. My solutions are much longer and more pedantic than yours need to be, so don't worry that the solutions are 9pgs long ... I tried to be explicit as possible, without skipping any steps. Also ... I have this obsession with exact answers involving many square roots, rather than approximate answers like 12.5, which lengthens things considerably. That's just how I roll.

Definitely read the solutions to the problems you missed, but at least skim the solutions to the problems you answered correctly - maybe you thought of a way I didn't, and vice versa.

Monday, July 13, 2009

Tomorrow's quiz / HW2 solutions

Tomorrow's quiz covers three main topics: (1) adding identical capacitors in series or parallel, (2) potential energy change of a charge moving from one voltage to another, (3) relationship between a constant E field and potential difference (say, when moving through a distance x). I will give the quiz at the end of lecture, so things may be a bit clearer by that point anyway.

Also, I have draft solutions of HW2 ready, and will post them some time before I sleep. Probably around 2am, i.e., after the deadline. Check back here in the early AM.

Numerical answers for HW2

1) Q = 0.957q (expressed in terms of radicals is better ...)
2a) flux through one side: 1.9e6 Nm^2/C
2b) flux in total 1.13e7 Nm^2/C
3) did this one in class; no numerical answer
4) larger charge is 12.5 times the smaller ones (again, exact answer preferred)
5) E = 4.4e5 N/C

Grades

By the way ... I'm going to experiment with using eLearning for the first time. Right now, you should be able to see your grades to date (specifically, for the first homework, quizzes 1 & 2, and the paper).

Not much else there for now, save my slides for Relativity and Electrostatics. I will probably try using the Tegrity business to record lectures this week. I had a demo of it last week, and was favorably impressed.

Mainly, this gives you an easy (?) way to see your current grades online. If you haven't used eLearning before, I'll try and give you a quick run-down on how to log in and check your grades Monday or Tuesday.

Lab for Mon 13 July 09

Monday's lab will be an investigation of capacitors. There is no need to read the procedure well in advance of the lab session, just form your lab group and begin reading it when you arrive at the lab session.

It isn't that we don't like you to be prepared - it's just that we haven't gotten to capacitors yet, so it may not make much sense for you to spend time on the procedure at this point.

That implies that tomorrow's plan for lecture is to get through electric potential and capacitors so you understand what the lab is all about. This means that I may reorder some of the material in tomorrow's lecture compared to the notes or textbook and pick it up on Tuesday. We'll see how it goes though ...

Regardless, either in lecture or lab, I will be going over some sample problems and giving out hints on HW2.

Sunday, July 12, 2009

Quiz 2 and its solution

Enjoy.

Also, this.

Homework 1 solutions

Here you go. Let me know if you find any mistakes or require further clarification ...

Saturday, July 11, 2009

Psst.

Practice problems.

If I asked it before, I'm likely to ask similar things again. Humans are lazy that way, and I am no exception. Be sure you understand Q7 on the multiple choice portion.

Friday, July 10, 2009

Electrostatics slides

Here are the slides I used during the two lectures on electrostatics.

HW2 is out

Here you go. Due by the end of Monday.

Thursday, July 9, 2009

Formula sheets on exams

Here's a question I just got:

I do have a question that I forgot to ask, Will we be able to use a formula sheet on the exam?
Yes. I'll provide all the basic formulas and numerical constants necessary on the exam itself, and you will be allowed to bring in one sheet of paper of your own containing any information you like. So long as your sheet of paper is 8.5x11 inches ... fair game.

Along those lines: if you find yourself needing a formula or number on a quiz that I have not already provided, just ask, and odds are I will just give it to you.

Videos of last summer's lectures

Here are videos of many of last summer's ph102 lectures, taken with the camera on my macbook.* Here's what I said about them last summer.

The quality is not awesome, and you cannot see the slides/demos due to the limited field of view. I haven't changed anything radically this time around, so the content is basically the same. On the other hand, I might have been more cogent last summer; this seems like a long shot.

Anyway: they are there waiting on the intertubes if you feel like you missed something or spaced out during part of a lecture ... I am not doing video again this summer because not many people actually watched them anyway, and the content has not changed.

* For the curious, I sat the laptop in the first row and recorded with the built-in iSight, a bluetooth headset, and quicktime pro. Works better than you might think.

Lab for Thurs 9 July 2009

Tomorrow, we'll learn about standard deviation and error analysis.

Procedure.

Slides for a quick demo/presentation I'll give before we start.

This lab is unrelated to relativity or electrostatics, but falls under the 'things you will need again' and 'relevant to everyday life' categories.

Wednesday, July 8, 2009

Quiz 1 and its solution

Here you go.

UPDATE: quizzes are graded, you'll get them back about 10 hours from now. The average was 87.5 with a standard deviation of 17.2. Basically, that means that the bulk of you did pretty well. Conveniently enough, a big part of tomorrow's lab is all about standard deviation and what it means ...

Most commonly missed thing: mixing up time interval and tempo. This doesn't worry me a lot - it is sort of a forehead-smacker once you see this pointed out, but it is tricky at the time.

Papers - hope to have them graded and handed back on Monday. They will count as much as one lab, grading-wise.

Lab for Wed 8 July 2009

We'll start the lab session by going over Thursday's homework problems, and then dive into the lab, a crash-course in research papers.

Here is the handout.


When you get to the lab session, download it and give it a once-over.

Relativity

Couple of random comments, since Tuesday's lecture probably seemed really tough.

(1) I think relativity is the hardest stuff we cover. We cover it first because we can make use of it later in a good way, and because it follows PH101 more logically.

(2) Particularly the first day, relativity is really bewildering. Typically, it makes a lot more sense on day 2, when we get a little bit further along and start to apply it in a concrete way. It is something like 'day 1: why things are weirder than we think' and 'day 2: shut up and calculate.' Day 2 is usually where things make more sense, or at least one just trusts the formulas we developed and tries to figure out what one can do with them.

(3) Based on the above, don't get too worried if today seemed like a rough start. It will make more sense on day 2, and the subsequent material is conceptually easy by comparison.

Tuesday, July 7, 2009

Wednesday's quiz

Wednesday's quiz will only cover time dilation, and it will be 3 questions long. Simple calculations, one-liners almost.

Example 26.1 in the textbook would be a good one to look at, as would problems 1.2 and 1.20 in the notes.* Seriously.

* It is either problem 1.20 or 1.21 in the notes ... the one about a clock running half as fast as it should.

Contact ...

Here is the email address which is most convenient for contacting me:

Today's slides

Here [pdf] is what I presented in lecture today. These are all the slides I used (course overview + relativity figures) as well as some example questions.

Homework 1 is due Thursday, we will go over some of the questions tomorrow during the lecture and lab sessions to get you started. You might have had trouble accessing this link earlier today (before about 12:30) ... that problem should be fixed now. Let me know if problems persist.

Also, tomorrow's quiz will be about 3-4 questions long, and cover length contraction and time dilation. You might find the notes useful [15Mb PDF]; there are problems & solutions at the end of the chapter. Note that the colored links are clickable in the PDF.

Homework / Quizzes / Labs / Exams

Here's the basic plan: quiz one day, homework the next. Repeat.

Every other day, you'll have a short quiz, usually at the beginning of the lecture. The quiz will be ~3-5 questions, and designed to take about 15 minutes. It will cover material from the previous day's lecture, and is meant as nothing more than a check to be sure that you're (a) paying attention in lecture, (b) doing the reading, or (c) both. As long as you didn't answer 'none of the above' you will be fine. Your first quiz is Wednesday 8 July, and it will cover the beginnings of Relativity (time dilation and length contraction only).

When there is not a quiz, there is a short homework set due. These homework sets will cover the previous two lectures or so, and will usually consist of ~5-7 problems. They will take some time - don't wait until the last minute - but will not be exceedingly difficult. Homework sets are not due until the end of the day specified, i.e., 11:59pm, and they can be submitted electronically (details forthcoming in class). Scanned pages are fine, as are digital pictures of sufficiently high resolution. Your first homework is due before 9 July at 11:59pm, and will cover relativity (basically the whole chapter / 2 lectures).

Labs are mostly self-contained, and will typically not require work outside of the laboratory period. There may be minimal exceptions, i.e., writing up reports that you could not finish during the allotted time. Lab material will be synchronized with lecture material as much as possible, and the beginning of each lab period will be devoted to reviewing any questions you might have about that day's lecture or the forthcoming homework/quiz.

There are two exams and a final: the two exams are given during the lab periods on 16 and 30 July, the final is 6 Aug at 8am. The two 'normal' exams will consist of 8-10 problems to be solved, and are designed to take ~90min (the format of the final exam is currently in flux). The first exam covers the start of the course through material presented on 15 July, the second exam covers material from 16 July through 29 July, and the final is comprehensive.

Ok: that's the official stuff out of the way ... it won't be so bad!

Welcome to PH102 / Summer 2009

Welcome to PH102! At the bottom of this page, or here, 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 will also show up online shortly, I will post separately here to let you know.

Finally, your first homework set is already due by the end of the day on Thursday, 9 July 2009. Have a look here. It isn't so bad, by the end of Wednesday's lecture you will know how to do several of the problems already.

See you at 10am ...