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.

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.

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.

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.