Slides for lecture 1 & 2

Here are some slides I'll be using for today's lecture, as well as part of tomorrow's.

Video of previous lectures

Back in the summer of 2008, I made videos of a good fraction of my PH102 lectures. Not everything is there, but you might find them useful as the semester wears on. You should also check out iTunes U, lots of nice lectures there, as well as an iPad/iPhone app.

Welcome to PH102!

At the bottom of this page, or here, you will find our course calendar, which you should review carefully. Note that if you click on any lab event, you will see a link to the relevant lab procedure. A separate table of the laboratory experiments can be found here. 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 tomorrow will also show up online shortly, I will let you know separately in a follow-up post.

Finally, I have written some fairly lengthy notes for this course, and my lectures will follow these notes for the most part. For this week, we'll be covering relativity, which is Ch. 1 in my notes.

Office move

Over the weekend, I had to move into a different office as part of some reshuffling we're doing to free up space. My new office in Gallalee is now room 323.

Some notes on transistors

UPDATE: the figure showing the internal diode-like connections of the transistor terminals had a mistake (the b-c one was backwards), now corrected at the same link below.

I just finished a first draft of. Two of the circuits discussed (current source, night light) are what we'll build in the lab on Wednesday. I mean build, not design - you aren't responsible for anything on these notes, you'll only be responsible for building working versions of the two circuits.

These notes are rough - I just wrote them tonight and haven't done much editing yet - but you might find them useful if you want to understand a bit more how transistor circuits work. The notes are not required reading, this transistor stuff isn't on any test or homework (and just one lab), it is merely ostensibly interesting and highly practical information. If you're curious, give them a read through. I have sections to add yet (how to build an amplifier and a few other bits), and I'll update the link as that happens.

For the actual lab on Wednesday, you don't need to read all of this or really know much about transistors at all. In fact, all you need to do is build them and measure there properties, which will be detailed in a lab procedure I'll post tomorrow. So, don't freak out, the lab itself will be entirely circuit construction and measurement (current vs voltage), no theory at all (but the circuits will do cool things). These notes are only if you want to figure out a bit more why the circuits behave the way they do, how they were designed, and how you can build your own.

As usual, if you notice mistakes or think something could be clearer, let me know. I plan to reuse these notes in later classes, so you would be helping future victims students.

Exam format

I had a couple of questions about the exam format, etc., so I'm reproducing my answer here for the rest of you to see.

The test will basically be 6 problems, and you can solve any 5 of them - so you can skip the one you think is hardest. Each problem will have multiple parts, so there is plenty of chance for partial credit (even within an individual part). A good example would be this one: 

http://faculty.mint.ua.edu/~pleclair/ph102/Exams/Sum_2010/ 

(This exam from last summer had them solve 6 of 8, but that ended up a bit too long). Again, heavy partial credit if you seem to more or less know what to do, but just make some small mistakes, or just get part of it right.

The formula sheet is totally unrestricted so long as it is 1 page of normal paper on both sides, or two sheets with only 1 side of printing each. Otherwise, it can have on it whatever you like.

The other section of PH102 this summer ...

They also have a blog. Some nice links posted there. (Both sections are covering the same material on the same schedule, fyi.)

Exam 1 is soon

Exam 1 is coming up on Thursday. It is rather soon, but there are reasons for this ... The exam will be held during your lab period, in the lab room. Even if you have my lecture and the 5pm lab, you still take the exam during your normal lab period. It will take you 60-90 minutes. Don't be late. Here's what it will cover, just two chapters:

• Electric Forces & Fields (Ch. 17 in the text, all sections)
• Electrical Energy & Capacitance (Ch. 18 in the text, all sections)

Note that relativity is absent.

The format of the exam will be 6 problems (i.e., solving stuff, no multiple choice), you pick any 5 to solve. Put another way, I'll give you 6 problems, you can skip any one of them you like, they are all worth the same amount. To head off an obvious question: if you do all six, I may grade all six and take the best 5 as your grade. Or, I might just grade the first 5. Who knows. Your best bet if you do all six is to tell me which 5 you want me to grade.

I will provide a formula sheet (example) with all relevant constants and basic formulas, a list which should be sufficient to solve all problems. Additionally, you are allowed to bring in a single 8.5x11 inch sheet of paper with your own notes, formulas, etc. -- anything you want, really. Front and back sides are allowed, I will allow two sheets with only a single side if you prefer that. You are additionally allowed writing implements and a calculator (i.e., not a cell phone or any network-enabled device). You can feel free to program your calculator in arbitrary ways, however, just no internet or peer-to-peer communication of any kind.

I don't know if I can stress enough that you should not forget your calculator.

Random Things

Thing the first: I really think the electric potential stuff will 'gel' for you quite a bit after the next lecture. We've just touched on it so far, in the next lecture we'll look at some practical problems and how to really use potential for calculations. We'll also be moving into more concrete subjects - the energy of crystals, circuits, etc. - and you'll have a little more intuition for what's going on. So, it is a lot of information at once, but be patient. There is a plan of sorts, and by exam time you'll be vastly less confused ...

Thing the second: check out the right sidebar. The 'course notes' are very extensive (nearly a complete textbook), and very close to what I follow in lecture. Following both the notes and the book is not a bad idea - if a section in the book doesn't make sense, try the notes & vice versa. They treat the same subjects slightly differently, you might find one explanation more to your liking than the other.

Thing the third: there are also many, many solved HW and exam problems you can access from the right sidebar. If you want example problems, or want to see what I've asked before on exams (the presumption that I will ask similar things is a good one), there you go ...

Thing the fourth: if you are in Dipanjan's section, we are going to have the same exam, same format. Details to follow soon ...

Syllabus

Course syllabus. Note that one lab and one homework grade are dropped. Repeat, one homework and one lab dropped.

Intro & relativity slides

Here are the slides from the first two lectures, which contain the intro/syllabus information and some figures for the relativity material.

Thoughts on the final

I posted this last year, and it still stands. 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. Rote memorization / cramming is not useful, but solving practice problems is.

(3) Cut your losses on the one chapter you really don't think you can master in the time remaining. You'll have a choice in problems, so you can avoid certain topics if you know the rest very well.

(4) Look at the previous final exams (spring/fall semesters mainly). They mostly don't have posted solutions, but I can tell you the answers at least.

(5) Few problems I have asked you before will appear on the final. Most likely 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 circuits. Capacitors have been done to death though.

(9) Study the homework solutions I have online.

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

(11) Answers/solutions to your outstanding homework/quizzes will posted soon, and will be good to study from.

Exam Guidelines

Exam 1 is coming up on Monday. The exam will be held during your lab period, but will take place in the lecture room. It will take you 60-90 minutes. Don't be late. Here's what it will cover:

Electric Forces & Fields (Ch. 15 in the text)Electrical Energy & Capacitance (Ch. 16 in the text)
Current & Resistance (Ch. 17 in the text)

See the course schedule for the particular sections in each chapter you are responsible for. Note also that relativity is absent. The material we cover tomorrow (Friday) will be on the test.

The format of the exam will be (approximately) 6 problems (i.e., solving stuff, no multiple choice), you pick any 5 to solve. Put another way, I'll give you 6 problems, you can skip any one of them you like, they are all worth the same amount. To head off an obvious question: if you do all six, I may grade all six and take the best 5. Or,  I might just grade the first 5. Who knows. Your best bet if you do all six is to tell me which 5 you want me to grade.

I will provide a formula sheet with all relevant constants and basic formulas, a list which should be sufficient to solve all problems. Additionally, you are allowed to bring in a single 8.5x11 inch sheet of paper with your own notes, formulas, etc. -- anything you want, really. Front and back sides are allowed, I will allow two sheets with only a single side if you prefer that. You are additionally allowed writing implements and a calculator (i.e., not a cell phone or any network-enabled device). You can feel free to program your calculator in arbitrary ways, however, just no internet or peer-to-peer communication of any kind.

I don't know if I can stress enough that you should not forget your calculator.

More details will follow over the next couple of days. For now, I suggest reading the chapters and old homework/exam solutions.

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.

Contact ...

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

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!

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.

Online matrix calculator

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

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 ...

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!