Today's review session; answer key to practice midterm problems

Echo 360 recorded it, but it turned off at 3 pm in the beginning/middle of going over problem 15. The technology used to capture the static images of the handwritten notes I put on the ppt slides via the pen-pad at the podium did not work fully. The quality of the handwritten images is not very good, and the system did not write it in a "lasting" way to the ppt slides. I don't know why. You can see the handwritten notes/solutions on the ppt slides in Echo 360, but only through problem 14. The answer key to all the problems on the practice midterm 2 is below:

1. A
2. D
3. Only true answer is C.
4. E
5. A
6. B, D
7. D
8. D
9. C
10. C
11. B, D
12. B,E
13. C
14. C
15. C
16. A
17. D
18. B
19. C
20. C

Good luck on Monday. Prof. Koch

Blackboard is down. Until it's back up, follow link below to practice midterm.

http://www.ic.sunysb.edu/Class/phy122ps/Fall2010phy122/Practice Midterm 2 PHY 122 Stony Brook University PM Koch 20101028.pdf

It's too long to fit on one line, and I don't know how to make it an active link in the blog, so make sure you cut and paste the whole thing without any spaces or deletions.

Prof. Koch

The practice midterm 2 is now posted

The practice midterm is now posted. See the Course Documents web page in Blackboard. Sorry for the delay. Good luck. See you Sunday at the review session in ESS 001, noon - 2 pm, to go over the solutions to it and answer other questions you may have. See the course blog for room assignments and other information about the midterm on Monday, 1 November, 8:30 - 10 pm. Prof. Koch.

Review session (noon-2 pm Sunday in ESS 001) and Practice exam for midterm 2 (delayed)

As announced yesterday in lecture, we will have a review session for midterm 2 in ESS 001 (our usual lecture hall) on Sunday, 31 October, from noon - 2 pm. It will be recorded on the Echo 360 system for later viewing by those of you who can't make it to the session or want to see again what went on. I will go over the solutions to the practice midterm and then answer questions from students who have them.

At lecture yesterday I promised the practice exam for midterm 2 to be made available by "this evening" (Wednesday), but it looks like I'm not going to make it by then. I'm working steadily on it and now expect to make it available by tomorrow (Thursday) morning.

Midterm 2: day/time/rooms

As you already know, the second midterm exam (on material in SV8 Chaps. 19 through 23 and in Labs 4 though 6) will be held on Monday, 1 November 2010, 8:30 - 10 pm.

Rooms and what to bring/not to bring: We have four rooms available for alternate seating, so please pay attention to where you're supposed to go in the alphabetical (by last names) sub-lists below. (For the cases where more than one student has the same last name, I've included the first name in the alphabetic filtering.) Each room will be filled to or near to capacity taking into count the alternate seating. Please be on time, bring more than one pencil for filling in the bubble sheet, bring your University ID (or, if you have lost/misplaced it, another form of ID that has a recent picture of you on it), bring a "standard" calculator (this does not include calculator operations built into, say, a smart phone or a netbook computer -- none of those allowed), and bring, if you want, one page of notes (both sides allowed) on whatever material you want personally to write down on it for helping you during the exam. During the exam: no voice/texting or any other cellphone activity. Turn off your cellphone and keep it out of sight.

Please be on time. Anyone coming in late will not get extra time. It's your responsibility to arrive well before the exam and wait quietly outside the lecture room being used for the exam until you're let in by the proctors.

Humanities 1003: Ahmed through Gerges

Javits 101: Ghotra through Li, Amy

Javits 103: Li, Joseph through Petruc

Javits 111: Pinto through Zhu, Judy

Exam forms: Be sure to record all necessary information on the bubble sheet including the "form number" of the exam according to the procedure used for the first midterm. We will remind you what that procedure is.

You should take home your one page of notes and the exam sheets, but of course NOT the bubble sheet!

Practice SV8 Chap. 23 HW: for MT2 prep.

Every problem in SV8 Chapter 23 is in that assignment. Scores will not be counted towards your grade - the problems are for you to practice is you want. This thread is a place to discuss any of those problems. In referring to any problem here, please identify it with the information that is at the right side of the blue bar above the problem, e.g., SERCP8 23.P.031

Practice SV8 Chap. 22 HW: for MT2 prep.

Every problem in SV8 Chapter 22 is in that assignment. Scores will not be counted towards your grade - the problems are for you to practice is you want. This thread is a place to discuss any of those problems. In referring to any problem here, please identify it with the information that is at the right side of the blue bar above the problem, e.g., SERCP8 22.P.005

Practice SV8 Chap. 21 HW: for MT2 prep.

Every problem in SV8 Chapter 21 is in that assignment. Scores will not be counted towards your grade - the problems are for you to practice is you want. This thread is a place to discuss any of those problems. In referring to any problem here, please identify it with the information that is at the right side of the blue bar above the problem, e.g., SERCP8 21.P.023

Practice SV8 Chap. 20 HW: for MT2 prep.

Every problem in SV8 Chapter 20 is in that assignment. Scores will not be counted towards your grade - the problems are for you to practice is you want. This thread is a place to discuss any of those problems. In referring to any problem here, please identify it with the information that is at the right side of the blue bar above the problem, e.g., SERCP8 20.P.015

Practice SV8 Chap. 19 HW: for MT2 prep.

Every problem in SV8 Chapter 19 is in that assignment. Scores will not be counted towards your grade - the problems are for you to practice is you want. This thread is a place to discuss any of those problems. In referring to any problem here, please identify it with the information that is at the right side of the blue bar above the problem, e.g., SERCP8 19.P.020.

SV8, Fig. 22.14: Useful graph for Lab 6, Part I.3

I just sent this to all students in the PHY 122/PHY 124 email list. Look at that email to get the jpg attachment of the figure described below.

************

Attached to this email is a jpg picture file of a screenshot I made of Fig. 22.14 in SV8. It shows graphs of n vs. wavelength lambda in nm for three different materials. One of these, acrylic (plastic), is the material used to make the prism you'll be using in Part I of Lab 6. Even though the the Lab 6 manual labels Part I.3 "Dispersion: qualitative only", you should try to be as quantitative as possible. This week's WebAssign HW problem 5 (which is SV8, Ch. 22, Prob. 32) is a quantitative problem on dispersion in a prism. You can use it as the basis for understanding Lab 6 Part I.3 in a more quantitative way. For this you'll need the dispersion curve for acrylic (plastic) in the attached Fig. 22.14.

Prof. Koch

PHY 124 Lab 6 pretest is now available

Please excuse getting this email twice, but I thought it doesn't hurt to make sure you get the word. I've posted this announcement on the PHY 122 Blackboard site, your PHY 124 lab section Blackboard site, and I've sent it via email from both Blackboard sites.

The PHY 124 Fall 2010 Lab 6 pretest is now posted for you to work on and submit before the beginning of your Lab 6 section next week. You will find it in the Assignments content area in Blackboard for your PHY 124 Lab section. As explained in the course syllabus, each Lab pretest is worth 35 points. As you will see, the Lab 5 pretest consists of 4 questions. The first is worth 5 points, the second is worth 5 points, the third is worth 15 points, and the fourth is worth 10 points, making the total possible score 35 points. To do the pretest you will need to study carefully the Lab 6 manual and to re-familiarize yourself with MapleTA syntax, which is used in the third question. Go to

http://www.ic.sunysb.edu/class/phy122ps/labs/dokuwiki/doku.php?id=phy124off:phy124_main_page

and read the instructions there on the "main page". Please also click on and review the

-- "Instructions" link (you've seen this before)

-- "Uncertainty, Error and Graphs" link (you've seen this before, and it's important for the third questions in the Lab 6 pretest)
and, finally, the

-- "PHY 124 Lab 6 - Reflection, Refraction and Images" link.

The "red" links are not yet active, on purpose, but as the course develops they will be made active.

As you already know, the lab pretests are prepared in the "Maple TA" software environment. You may work on each assignment as many times as you wish, but the link in the Assignments section of Blackboard for your PHY 124 section will become inactive at the starting time of your lab section. Therefore, you should not wait until just before your lab section to begin work on it. If you read the Lab Manual carefully and, there is no reason for you not to earn all 35 points for the pretest. Make sure you read carefully the instructions for each pretest problem. After each problem click on "Next" until finishing the last one, Question 4; then make sure you click on "Grade" in the Maple TA software environment. After you get your grade, you may click on "View Details" to see more about how you did. Finally, click on "Quit and Save".

Good luck!

Prof. Koch

Combined Ch.22,23 HW: 10-12 (from Ch.23)

Combined Ch.22,23 HW: 7-9 (from Ch.23)

Combined Ch.22,23 HW: 4-6 (from Ch.22)

Combined Ch.22,23 HW: 1-3 (from Ch.22)

Clicker scores: 10/19/10 and generally

Yesterday, 10/19/10, I made a mistake by ending clicker question 2 way too early. Some students asked yesterday after lecture and later by email or blog if I would correct this. The answer is yes. I posted the clicker grades yesterday but corrected them just now this morning. I deleted the former Blackboard gradebook column "CPS 10/19" and put in its place "CPS 10/19 edited". I gave credit for clicker question 2 to any student whose clicker registered any response to clicker questions 1 or 3 independent of whether that clicker had responded to 2. I did not give credit to any student whose clicker did not respond to question or question 3 because I took that as evidence for not yet being present/responding in the lecture hall.

Generally: Some students have asked about the maximum clicker score each lecture. I gave the incorrect answer to at least one student. Here is the correct answer: The maximum score for each lecture is 100 points. If ten questions are given and scored (including the freebie), each is worth 10 points. If nine questions are given and scored, each is worth 11.11 points. If eight questions are given and scored, each is worth 12.5 points, and so on.

I have also posted this as an announcement on Blackboard and sent it to all students by email.

Prof. Koch

Lab 5 pretest is now available (PHY 124 part of course)

The PHY 124 Fall 2010 Lab 5 pretest is now posted for you to work on and submit before the beginning of your Lab 5 section next week. You will find it in the Assignments content area in Blackboard for your PHY 124 Lab section. As explained in the course syllabus, each Lab pretest is worth 35 points. As you will see, the Lab 5 pretest consists of 2 questions. The first is worth 14 points, and the second is worth 21 points, making the total possible score 35 points. To do the pretest you will need to study carefully the Lab 5 manual and to re-familiarize yourself with MapleTA syntax, which is used in both questions. Go to

http://www.ic.sunysb.edu/class/phy122ps/labs/dokuwiki/doku.php?id=phy124off:phy124_main_page

and read the instructions there on the "main page". Please also click on and review the

-- "Instructions" link (you've seen this before)

-- "Uncertainty, Error and Graphs" link (you've seen this before, and it's important for both questions in the Lab 5 pretest)
and, finally, the

-- "PHY 124 Lab 5 - AC Circuits " link.

The "red" links are not yet active, on purpose, but as the course develops they will be made active.

As you already know, the lab pretests are prepared in the "Maple TA" software environment. You may work on each assignment as many times as you wish, but the link in the Assignments section of Blackboard for your PHY 124 section will become inactive at the starting time of your lab section. Therefore, you should not wait until just before your lab section to begin work on it. If you read the Lab Manual carefully and, there is no reason for you not to earn all 35 points for the pretest. Make sure you read carefully the instructions for each pretest problem. After each problem click on "Next" until finishing the last one, Question 2; then make sure you click on "Grade" in the Maple TA software environment. After you get your grade, you may click on "View Details" to see more about how you did. Finally, click on "Quit and Save".

Good luck!

Prof. Koch

Chap. 21 HW: Problems 9-12

Chap. 21 HW: Problems 5-8

Chap. 21 HW: Problems 1-4

Extension of Chap. 20 HW to 15 Oct.

I already put this on the Blackboard announcements page for PHY 122 and sent it to all students by email:

PHY 122 students,

Responding to an email from one of the students, I wrote the following:
Yes, [at yesterday's = Tuesday, 12 October lecture] I didn't cover all of inductors and didn't cover the RL circuit because the microphone-volume problem at the beginning of lecture cost me the 10 minutes that I needed at the end. By my reckoning, problems 9, 10, 11, and 12 involve the above material. I did cover part (b) for problem 9. All these four problems are direct applications of formulas in the text, and most of them are very similar to worked example problems in sections 20.7 and 20.8 of SV8 Chap. 20. I just checked the Chap 20 HW grades for all students in the course; most students have worked out these problems, but to be fair to all, I've decided to extend the deadline for the Chap. 20 problems to 5:00 pm on Friday, 15 October. At the beginning of tomorrow's (Thursday, 14 October) lecture, I'll cover the rest of the material about inductors and the RL circuit.

Prof. Koch

Lab 4 pretest went live mid-afternoon Saturday, 9 Oct.

You should have received an email reminder. I hope you will find Lab 4 to be a particularly interesting one, but there is a lot to do. Please make sure you're well prepared and work diligently during the lab period.

Chapter 20, Problems 9-12

Chapter 20, Problems 5-8

Chapter 20, Problems 1-4

Practice Chapter 18

Every problem in SV8 Chapter 18 is in that assignment. Scores will not be counted towards your grade - the problems are for you to practice is you want. This thread is a place to discuss any of those problems. In referring to any problem here, please identify it with the information that is at the right side of the blue bar above the problem, e.g., SERCP8 18.P.018.

Practice Chapter 17

Every problem in SV8 Chapter 17 is in that assignment. Scores will not be counted towards your grade - the problems are for you to practice is you want. This thread is a place to discuss any of those problems. In referring to any problem here, please identify it with the information that is at the right side of the blue bar above the problem, e.g., SERCP8 17.P.018.

Practice Chapter 16

Every problem in SV8 Chapter 15 is in that assignment. Scores will not be counted towards your grade - the problems are for you to practice is you want. This thread is a place to discuss any of those problems. In referring to any problem here, please identify it with the information that is at the right side of the blue bar above the problem, e.g., SERCP8 16.P.018.

Notice the SV8 problem numbers in the WebAssign HW assignments

This may be helpful to all of you for the WebAssign HW. I think that most of you refer to the WebAssign problem numbers (1,2,...,12) when doing the weekly assignments. You should also pay attention to the information at the right-hand side of the "blue bar" for each HW problem. For example, for the Chap 19 HW, it will say SerCP8 19.P.0xy, where xy is a two-digit number giving the problem number at the end of, in this case, Chapter 19 (of Serway and Vuille, Classical Physics, 8th edition). It will be helpful in many of the problems to look at what's in the book, not just what's on the WebAssign HW "pages" you view on the computer screen. Reason: there may be (a) figures(s) in the book, near the text of the problem, that will be useful to you for solving the problem. A case in point is Chap. 19, Problem 38 (which is the WebAssign #8 for Ch. 19 HW). To understand the geometry/layout of the "mass spectrometer" mentioned in the problem, look at the right-hand side of Fig. 19.36. This is what's envisioned for Problem 38. In this case, even more useful is Example 19.6 on p. 641 of SV8. Fig. 19.22 shows the pictorial layout of the mass spectrometer, and the example problem is very similar to Problem 38.

Chapter 19, Problems 9-12

Chapter 19, Problems 5-8

Chapter 19, Problems 1-4

In the first problem, the range between maximum and minimum comes from the relative direction of the magnetic field and the electron's motion.

Practice Chapter 15

Every problem in SV8 Chapter 15 is in that assignment. Scores will not be counted towards your grade - the problems are for you to practice is you want. This thread is a place to discuss any of those problems. In referring to any problem here, please identify it with the information that is at the right side of the blue bar above the problem, e.g., SERCP8 15.P.018.

Practice Midterm Exam

This thread is for discussion of problems in the practice midterm exam, which is posted in Blackboard in Course Documents.

Lab 3 pretest is now available

I posted the announcement for the Lab 3 pretest availability for all PHY 124 sections and sent it to each of your email addresses (the ones that Blackboard accesses). As usual, the pretest assignment will be available to you until your lab section begins.

Prof. Koch

Chapter 18, Problems 10-12

Problems with resistors and capacitors, from Section 18.5.

Chapter 18, Problems 7-9

These problems require application of Kirchhoff's rules for more complicated DC circuits. See section 18.4

Chapter 18, Problems 1-6

These problems pertain to sections 18.1, 18.2, and 18.3. You should be able to deal with all of them using combinations of series and parallel resistors.

Note that question 4 part C asks for the power delivered by the battery, but the dimension given with the answer is Amperes. That should be Watts. (Doesn't affect how you approach the problem -- I just mention it to avoid possible confusion.)

Chap 17, Problem 12

This problem is a bit tricky. Start by drawing a diagram, and note that the question asks for the power delivered to the cleaner, which would exclude power that heats the extension cord.
Also, see my latest post about the need to calculate intermediate results to an accuracy much better than 1%. You should be safe with six significant digits as you are working.

Chap 17, problems 9 - 11

Problems from SV8 Section 17.6. The language of #10 (Problem 17.36) is a bit ambiguous. Part b should say, "What percentage of the power generated by the power station does this loss represent."

Chap 17, Problems 7 and 8

Problems from Section 17.5.

Chapter 17, problems 4-6

These problems are from Section 17.4. For the fifth one (SV 17.12), you might find yourself with two equations involving length and area of the wire: the given mass gives you L*A, and the resistance gives you L/A. Multiply those two equations together and it eliminates A.

Chapter 17, Problems 1-3

For 2 and 3, you need to convert a given mass or density of metal to charge or charge density. I think it's easiest to visualize this as a unit conversion problem, for example, the density of Al is 2.7 g/cm^3, which you want to convert to electrons/m^3. So multiply by unity in various forms to clear the dimensions. For example (1 mole / 27 g of Al), (How many atomis is it? / mole), (conduction electrons / atom), ...

Lab 2 pretest is now available

Please see the Announcements web page in Blackboard for your PHY 124 lab section. To avoid clutter, I took down the previous announcement about the Lab 1 pretest. The Lab 2 pretest announcement will remain up for each lab section until that section meets to do Lab 2. I'll do the same for future labs. As I did for Lab 1, I sent the announcement via email to each student in each section. If you did not get it, something is not right with your email. This could be that the University does not have the email address that you are (now) using. It's up to you to correct this. Instructors using Blackboard to send email to students do not see the email address being used for each student.

Chapter 17

I'll break this up into more threads soon, but if anybody is getting a head start, there are a couple of things I want to point out. In a couple of problems, you will need to find densities, atomic numbers, etc. of certain elements. This kind of info is readily available on the web, and you have a periodic table with some of this info in the back of your book. Likewise, the book contains a table of resistivities and thermal coefficients of resistivity (page 577).
The statement of part of the 10th question (SV8 17.36) is poorly phrased; part b) should read, "what fraction of the power that is generated at the power station does this loss represent."
Careful with dimensions throughout. Look at the dimensions furnished with the answers. millimeters, micrometers, percent, ...

PHY 124 Lab 1 pretest

Students (and TA staff) in all lab sections should have received email on Tuesday (7 Sept) night about the Lab 1 pretest being posted in the Assignments section of Blackboard for your lab section of PHY 124. The email was the same Announcement that also appeared on Blackboard. I know that many of you have logged in and at least started the Lab 1 pretest, which exists within the Maple TA "plugin" for Blackboard. There are 5 multiple-part questions in the pretest; each question is worth a maximum of 7 points, giving 5x7=35 points maximum in all. Partial credit is given for partially correct answers, but there is no limit on how many times you may re-do the pretest. You may check how you did on each question, and when you're done with an attempt on the whole pretest, you may check your overall grade for it. I logged in as a student, took the pretest, and did all of these steps. So far, as the instructor I am able to monitor how many students are logged in on the pretest for each section, but a software glitch prevents me from seeing the pretest grades for each student. The Blackboard support staff is now working to correct that.

Make sure you do not wait until the last minute to complete the Lab 1 pretest because, as was contained in the Announcement/email, you will cease to have access to the pretest at the time your lab section begins.

Good luck!

Prof. Koch

Chapter 16, question 12

This question, SV8 problem 16.52, has some problems in its wording. First, the capacitor is made from two strips of aluminum foil, separated by paraffin-coated paper. The question wants you to think about the capacitor unrolled, so that there are two flat plates, separated by one layer of the dielectric. What are the dimensions of that configuration in order to have the given capacitance? (Then, as an editorial note, the statement of the problem goes on to say that if you put in another piece of paper and roll the thing up as illustrated, it will actually have twice the capacitance because now charge accumulates on both sides of each plate, essentially doubling the active area.)

Chapter 16, questions 10, 11

These two questions refer to material in SV8 section 16.9.

Chapter 16, questions 7-9

These two questions come from SV8 sections 16.6 and 16.7.

Chapter 16, Questions 3 through 6.

These questions are from SV8 sections 16.2, 16.3, and 16.4. Please try to look at them before the September 7th class.

Chapter 16, Questions 1, 2

Remember that this homework assignment is due on Wednesday, September 15th at 5:00 PM.
This thread is to discuss the first two questions, which come from SV8 section 16.1

Chapter 15, questions 10-12

These three questions are from SV8 sections 15.6, 15.8, and 15.9. The whole assignment is due on Tuesday, September 7th at 3:30 PM.

Chaper 15, questions 5-9

These five questions are from SV8 section 15.4. The whole assignment is due on Tuesday, September 7th at 3:30 PM.

Chapter 15, Questions 1-4

These four questions are from SV8 section 15.3. The whole assignment is due on Tuesday, September 7th at 3:30 PM.

Welcome to Physics 122

Once the course gets going, this will be a forum for discussing homework problems and the like. You can post questions and comments, and your instructors will be following closely.