Year-End Testing:

 

We will start doing some sort of brief quiz every day. The first of these will be on Thursday, March 29, and the topic of that will be the remainder of the Quantum Physics unit, including the Photoelectric Effect. On later dates, including April 9, I will give some indication of the topics covered on each daily quiz. Quantum Physics will be completed on March 29. April will revisit certain older topics and do AP Exam review.

 

The course final exam will be on Thursday May 3. It will be a simulated AP exam. You will review for it early, as you would for successful AP exam performance. Materials for AP mock testing will be coming soon. The real AP exam is the week after the final.

 

You have all of your Quantum Physics materials on paper and online, so complete your study and reading of that unit by March 27.

 

We'll do something graded with the Photoelectic Effect on PhET, and I'll explain that in class on 3/27. So study the topic ASAP.

Test on March 19 on Chapter 28. It was announced on March 15, because I decided to schedule it on March 15 after so few people did the thing I said to do on March 9. So I'm forcing the issue, and none of this is new or beyond anyone's knowledge. People who were absent on March 15 are still taking this test (or large quiz or whatever you want to call it), because through this posting that you're reading right now, they have the same access to practice information that everyone else has. This test (named as such to get people's attention because they didn't do March 9's HW) covers the content of what was developed in class last March 9, and anyone who didn't understand that has had 6 days until now to come ask me questions about it. (And yes, I was fully on campus on Wednesday, March 14). Anyway, here's some practice attached, there is more in Chapter 28 problems. People who did the HW I assigned on March 9 (and we went over it together on March 15) have little to worry about from this test. (Again, or large quiz or whatever you want to call it. But do some people only notice if I use the word "test"?)

 

Read Chapter 28. I said that over a week ago. If someone asks me "is such-and-such gonna be on the test", I won't answer, because if it's not in Chapter 28, it won't be on the test. So I've already answered the question.

 

To do the practice quiz with 2016 in the title, you'll need to find your textbook's story on something called the Photoelectric Effect. You'll need to read about that in the semester soon anyway, so why not now? If you choose not to, you might not be able to take advantage of the 2016 practice test attached.

 

"A Modest History of Modern Physics" is a paper I wrote some years back. It doesn't deal exclusively with Chapter 28, but can give perspective, and also includes a little bit of additional Chapter 28 practice if you have time for it. You'll be reading it soon in the class anyway.

 

Chapter 28 Book Problems I like: 11 through 26, 44 through 50

 

The pdf file contains a Problem 7 to use for practice, Parts a and b only. Consider this part of the attached file named "Bohr Energy Quiz". Bohr Energy Quiz Key will tell you the answer to Problems 7a and 7b from the pdf. I do not like the College Board's key for the pdf problem 7. It's conceptually misleading.

Bubble Problem - in 2/27/18's class, it was fully analyzed as the Oil Slick rainbow problem

 

To go with this, you're emphasizing in the textbook the reading of pages 786- 797.

Homework Due Wed. 2/14: It's explained in the Study Guide attachment

 

And some templates for Ray Tracing attached - The filenames say "Ray Tracing Homework" but I'm not collecting ray tracing on 2/14. That doesn't mean don't do them though. They're good study aides. The homework that you have to do for me is described in the Study Guide attachment.

Practice Optics Tests - Real test is Friday 2/16

Answers to the Physics 2 "Section 1" Practice AP exam that I gave to Per. 1 in class on 1/16/18:

 

1. B

2. B

4. A

5. C

6. C

7. C

13. C

14. A

15. B

16. D

17. C

18. C

19. A

21. D

22. C

31. D

32. B

33. D

34. A

35. A

36. D

37. C

38. B

39. D

40. D

41. B

42. B

45. B

46. A, C

47. A, B

48. A, C

An AP Physics 2 Practice Multiple Choice Compilation - attached here. Answers on last page of doc.

 

Are you also using this site?

 

 

Sample FR Questions from the years 2015, 2016, 2017, and examples of how to score them.

 

Just like the site I showed you months ago?

 

 

This is why I feel you've had no shortage of practice items since I told you the topics in December.

 

I'll make one more MC test available in class on Tuesday. One that I'm not allowed to post online.

Magnetic Field (Chapter 20, EM Induction) Lab Practice for Home:

 

Any files I attach here are powerful for giving more tries at the types of things that were available on Tuesday. On Thursday, 1/11, what you do with demos like these will count for credit.

 

Use Lenz's Law Discovery Template when you go through the step-by-step analysis of "Hovering Ring", of "Inducing a Current by Removing The Bar Magnet", of "Motional EMF", Page 1, of "Bar Magnet Falling Into A Copper Pipe", of "Bar Magnet Falling Out of A Copper Pipe". Notice these last two don't have worksheets. You've seen them enough time. You diagram and answer for their template quantities after you've done the "Hovering Ring" and "Inducing a Current by Removing The Bar Magnet" to get the hang of the communication process.

 

Before you do "Inducing a Current by Removing The Bar Magnet", you have to understand what's in "Interpreting The Meters Correctly To Know The Flow".

 

"Lenz's Law Discovery Template" is to be used right away.

 

"Lenz's Law Application Template" is not to be used until it's time. You will know.

Reminder: Magnetism Practice Documents have been available, posted since December 27. See the posting from December 27 that originally said "Due Jan 3". (You might have to select "Show all assignments" to see it.) There is a LOT of practice in that posting to solidify Chapter 19 - with answer keys available. The practice documents have the following names, (but I don't need to tell you, because you got the documents on your own, right?):  "Field Comprehension Check - 3 Basic Sources", "Diagnostic Definition Comprehension Quiz", "B2000 #7 Quiz".

 

The one called "Diagnostic Definition Comprehension Quiz" has its key in the same file as the original questions.

 

These cover a lot of good things, and why stop there. You know the Study Guide has even more questions from out of the book, and I posted a file with all the even answers from Chapter 19 book practice that I had placed on the Study Guide. So I hope each person uses what I gave.

 

Here is one more for you. "Wire on Wire". I said in class I'd give this to you to supplement the activity in class where a wire running current magnetically attracted or repelled a second wire also flowing current.

 

(By the way, Wire on Wire is the key analysis that proves why magnetic poles are NOT fundamental.)

 

The Practice Quiz entitled "Field Comprehension Check - 3 Basic Sources", asks questions about the strength of field inside the solenoid. Did you think that was unknowable or optional just because I didn't state it in class? That would be an untrue statement. Did you read Chapter 19 as instructed until you knew the meaning of the formula for the magnetic field inside a solenoid, and how to use that formula. (The text has good pictures; it makes it clear, and you know what a solenoid looks like, because you used them in my room.) In my experience, a minority of people become aware of the meaning of this particular solenoid formula even when directly instructed to find out about it, and I know that this is because a minority of people read with sufficient depth, physically defining every symbol without exception. It's your job to be outside of this unfortunate norm. FYI: my lab solenoids have 540 circles (AKA turns) of wire fit into a column that's 15 cm tall.

 

Summation: yes, I did assign knowing the solenoid, because I said to read Chapter 19. I could tell you the page it's on right now, but I won't, because everyone can read.

 

About "Velocity Selector Lecture Problem": That was a cool little practice quiz also posted on December 27 (and re-attached here). I've attached some things to this posting for that:

 

1) The key to Velocity Selector Lecture Problem BUT don't necessarily open the key if you didn't know what to do on "Velocity Selector Lecture Problem". How come? See #2.

 

2) Remember in class one day when I gave you the multipage document called "Velocity Selector Solution Breakdown"? Well, I did. This is a long discussion that talks about every possible important thing that in the end shows how simple the Velocity Selector's final solution is. Anyway, you were already given that file, and it's re-attached to this post. It reviews electricity as well as magnetism.

Final Exam Information

 

Attached are some Multiple Choice Sample Tests. For now, answer what you know on them to get the feel for the thinking involved. Many of the topics on these will be things on your exams, but some will be old review, and then there will be some things not covered yet. But just do it for now to measure what you can do.

 

This is to get you used to CollegeBoardish exam questions in multiple choice. (There will be some multiple choice questions on the final taken from old AP exams.) See how it goes. I posted exams from 1993 and 1998. Do this early. This is set up for you to see early, and then we go over in class and then adjust. People who only use these multiple choice exams when the final is days away are people who get ZERO benefit from them.

Chapter 19 Materials - Chapter 19 is on the final. Here's an early start to a huge chunk of the final, like 40%. Another posting talks about Final Exam Topics. And that page mentions Chapter 19 Study Guide material under another posting. This is that other posting.

 

Read Chapter 19 early and efficiently. When you are done with that, you can use any of the documents below to measure how strong your reading comprehension was. I'll be doing this stuff fully in class on January 4, but don't wait for me. Do your study early. You're all set up with the textbook and all of these practice attachments.

 

"Velocity Selector Lecture Problem" is a puzzle problem. It would be to measure mastery of efficient use of many concepts.

Resistor Circuit Breakdown packet (in case you forgot from Physics 1.)

 

This has application to the capacitor experiment expectations.

 

I've also posted another example that's relevant to the experiment. It was the one where the capacitor is in series with a 4000 ohm resistor. A 5000 ohm resistor was in series with the power supply. And a 7000 ohm resistor was in parallel with the capacitor/4000-ohm branch. The battery voltage was 12 V.

 

The problem is this: What final voltage will the capacitor reach if it is hooked up as described above for a really long time.

 

Why not do it on PhET, but just with R values of 40 ohms, 50 ohms, and 70 ohms. Do that! It's fun!

 

The file I just attached (UPDATED) is based on doing that on PhET. Right now, it's posed as a problem with solution discussion.

 

That's it for today's posts.

Document necessary for Wednesday's HW

Capacitor Packet that's due Thursday 12/7

HW Packet that uses PhET for Charge, field, voltage, and capacitance, as described in class. (Using two PhET sites in comparison.) Due 11/29

HW Due Monday 11/27 - this attached packet is to be done carefully.

 

People who fell behind especially need this posted attachment completed before Monday 11/27, and that's why it's due then. I did point this out in class, and showed you the document that I've I posted here. Follow its directions; it's five pages, and there is writing and math required. And you're supposed to be going beyond the bare minimum of this document by also reading Chapter 16 (at least the part before capacitors.)

 

People who recently chose not to look up the E field of the flat surface of charge and do it by Monday 11/20 are people who willfully chose to fall behind recently on the most abstract topic of the semester. There is a reason I assigned that question, and it relates closely to voltage, and anyone who didn't do it meaningfully chose to make that topic harder. I walked into Tuesday Nov. 21 with the plan of highlighting that 11/20 HW fact and using it to make this topic easier, and I was going to do that and say Happy Thanksgiving. Enough people didn't do that HW that I was unable to do so, and now many people have more HW over the Thanksgiving weekend as a result.

Materials to Help You Prepare for the Superposition Quiz on Tuesday 11/21:

 

Note: if you've been here before 8:35 on 11/18/17, you saw an attachment called Lesson 1. If so, you might be wondering why Lesson 1 is now gone. Don't worry about it. I have made you something better for practice, and I have deleted Lesson 1. So read now what I have for you in this posting; it's the best practice I can lay out for you, and it's better than Lesson 1... (You don't need Lesson 1 but if you used some of it on 11/17 and 11/18, it wasn't bad and wasn't a waste of your time.)...

 

Note the attachment now and download it. It walks you through a practice problem. Once you do it and see its value, you can unleash the skills it promotes on the following additional practice:

 

Your textbook, Page 526: Problems 24 - 27, then 12 and 13 on Page 525.

Solve for the E field in Problems 12 and 13. The book tells you to solve for Force. No, I say. Solve for the E field. You need that practice.

 

Page 528: Problem 49

 

And of course, you've seen the solved Example 15.5 on Pages 508-509 (because I made you read that in class.)

 

Vector addition takes practice. When I have people do it for a grade, like on a Quiz, the grade distribution tends to be a lot of A's, some F's, and nothing in between. It's nice when it's zero F's.

 

For your practice, you'll need me to post the answer to the even problems in the book. I'll do that ASAP by the end of 11/19/17.

 

Finally, back to the Superposition Notes I have attached here. Notice, they have illustration from a PhET diagram. That means you can fire up the Internet, and you can open the PhET site, and you can make this diagram too, and you can play with it.

 

And that means that you can then use PhET to make up many more vector addition of E field practice problems. All you have to do is make up some charge distributions by plunking down red and blue charges. Then pick some random point near the charges, and say, "OK, me, predict the total E field at that random point." Do the math fully on paper. (You have to pay attention to the fact that the each source charge is 1 nC.) Once you have your total E field answer in N/C, place the yellow puck at your random point, and PhET will tell you the answer you should have gotten. (PhET's answer will be in V/m, while yours is in N/C. Exercise: Prove that these two units are equivalent.)

HW due on 11/15: A brief problem about flux, field, spheres, and cylinders.

 

Use this Attachment if you didn't know EXACTLY what you were solving for in class. This is the one I said I'd post.

Correct your thermo test image by Monday. Report two scores, one for each problem, each out of 10.

 

Use this link to find the rubrics you are to use:

 

 

And use this link all year for the rest of the year for all high quality practice testing on all topics.

Chapter 12 Practice Test Key

HW was to identify the total heat exit from the system and the total entry into the system for the triangular shaped pV graph that was most recently used in class. I then said that when you are done, check what you got versus the answers I am posing online. That posting is here:

 

Heat Released = -2,250,000 J and occurs in only one stage of the cycle. The absolutely value of this is what the textbook calls Q-subH in the heat pump section of Chapter 12. Make sure you have read that.

 

Heat Absorbed = +1,950,000 J and occurs in two stages of the cycle. The absolutely value of this is what the textbook calls Q-subC in the heat pump section of Chapter 12. Make sure you have read that.

 

Reading Comprehension Check: Do you know how to calculate the coefficient of performance of this cycle when run as a refrigerator? (The answer is 6.5. Understand how to prove that.)

 

Reading Comprehension Check 2: If this cycle were run in reverse, it would be called a Heat Engine. Using the reading in Chapter 12, calculate the efficiency of this cycle when run in the direction of Heat Engine. Tell me this answer or ask about it when you come to class on Tuesday, October 31.

 

Sidenote: I did some homework to teach myself how to calculate the average temperatures at which the three stages of the triangular cycle occurred. These values would be needed to calculate the entropy change per cycle. What's interesting is that all of the above numerical answers in this posting are gettable without knowing how many moles of gas there are running through the cycle. However, once you want to calculate the increase of entropy (AKA, the increase of randomness created by a cycle), you do have to know how many moles of gas are involved. I didn't know that conceptually until I sat down to calculate the entropy changes. I'll show it in class.

The Chapter 12 Practice Test - This now contains the hints you need in order to get the works correct on the curved sections of a given graph. Now take the test mathematically, and look for the key to be posted sometime between 10/29 and 11/1.

Due Monday: Chapter 12 Intro Topic: Specifically, how to calculate work done by or on a gas from a Pressure versus Volume Graph. I explained this in class. But I also said I would post more practice information for guidance. That is attached. I call it a Study Guide. Read the whole Study Guide.

Chapter 9 Test Rubric: Posted here is the updated, final draft version of my rubric. Download it to execute the Grade-Your-Own homework assignment that I gave, due October 3.

 

There are 25 points possible on this test. Use the rubric to grade yours. If you match the points that I judge your paper as worth, you'll get more test credit.

Unsolved Test Questions: Chapter 9 Test Original Questions Form

- in case you need it.

 

Also, an addition to the Solution to #4B: To explain why the refined speed is less than the approximate speed that had been found in Part A, you can give a simple verbal proof. One can meaningfully say that factoring in the pressure difference is equivalent to factoring in the negative work done on the water system at the low altitude and the positive work done on the water system at the high altitude. The negative work is proportional to the low-altitude pressure, and this is the higher of the two pressures, since pressure increases with depth in the environmental fluid. Since the negative work density is greater than the positive work density, the overall effect is to decrease the kinetic energy that gravity can give to the fluid, and hence the refined speed is lower. So my algebraic proof in the Rubric for 4B can be replaced by a clear statement like the one above.