Friday, July 15, 2011
Wednesday, July 13, 2011
HW2 #7
Q1: On problem 7 (Moving a Charge) of the second homework set I keep getting this error message when I input my answer in a variety of different ways: "There is an error in your submission. Make sure you have formatted it properly."
Q2: I'm sure I have problem 7 right, but it is being marked wrong.
I've gotten these questions many times already, and in almost every case you did have the right answer. For some reason this problem is weirdly particular about the order the operations (superscript, subscript, square root) are put in.
If you definitely have the right answer, and can prove it (screen shot, copy & paste, etc), show me and I'll just go in and override your score for that question to give you full credit.
If this happens more than (roughly) 20 times, I will decide it is not worth the effort anymore and will give everyone full credit on #7 :-)
Exam practice problems
Your best bet is to dig around in the exams from previous incarnations of PH102 - just about all of them have solutions too.
Look at the first exams for any given year, the one from Summer 2010 is probably most relevant. Old HW problems are also good, and almost all have solutions:
The only trick is that HW problems are usually harder than exam problems (at least in the past, when I didn't use online HW).
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.)
Tuesday, July 12, 2011
Wednesday's lab: electrical components
UPDATE: I've included another part of the experiment in which you'll learn about the function of photoresistors, and a bonus circuit construction project where you'll build an 'electric eye' circuit if you want some extra points. The files are in the same directory linked below
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Wednesday's lab is a simple one on components, designed to introduce current & voltage and operating the lab boxes. Find it here: http://faculty.mint.ua.edu/~pleclair/ph102/Labs/components/ (2 parts, 2 files).
One small warning, of sorts: this lab is not at all as obvious as it seems when you take into account non-idealities of components, sources, and meters. Once you've seen it once, though, it is straightforward. That is part of the point of the lab - how to real components, sources, and meters work, as opposed to the ones in the textbook.
I will probably add a small section to the lab at the end where you will explore photoresistors and LEDs combined to make a simple sensor-actuator setup, just a qualitative thing where you describe what happens. I will post the revised procedure late tonight.
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)
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 ...
Monday, July 11, 2011
Relativity HW extended
I'll push the deadline for the relativity HW until Friday so you can worry about the test more efficiently.
This will not affect the HW2 deadline, nor the occurrence of HW3 shortly thereafter.
(This is for Dr. LeClair's section only. Dr. Mazumdar may or may not decide to do the same.)
Sunday, July 10, 2011
HW2 is out
Your second homework set is out (LeClair's section), due Wednesday at midnight. It is a bit longer than the first, but meant to double as study material for Thursday's exam. More details on that later, however ... for now, suffice it to say that you should not delay in starting the second homework.
There is likely to be a shorter homework due on Friday covering current & dc circuits.
Tomorrow's lab
Tomorrow, you will measure equipotential lines. A lot like electric field lines, we'll learn about them in the lecture.
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.
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