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.