PHYS 1220 Round 3 Retests

The third round of retests comprised the first retests on Standards 13–19 from Exam 2, the second retests on Standards 7–12 from Exam 1 and the third retests on Standards 1–6 from Quiz 1.  Each standard had its own retest quiz on Canvas.  If you hadn't satisfied a standard from Exam 2, you were automatically eligible to retest in this round.  If you hadn't satisfied an earlier standard, you needed to review the material with an instructor, tutor, or TA to access a retest.

Grader's notes

I missed retesting on Standard 1.  Oops.  I'll have to make up for that next time.

I apologize for Question 2 on Standard 11 Retest 2.  I don't like any of the answer options, and the whole thing is confusing.  If that question gave you problems, it wasn't just you.

On Standard 12 Retest 2, the answer key for Question 2 was incorrect.  I have hand-graded the answers.  The question was about a free expansion of gas into a slightly larger volume, from v₁ to v_f = v₁ + v₂.  The answer should have been nR ln(v_f/v₁).

In Standard 13 Retest 1, some students entered coefficients of performance as percentages instead of decimals.  I think I caught all of those to give them credit.  If I missed yours, let me know.

Standard 14 Retest 1 had a couple questions with incorrect answer keys.  These were questions about the electrostatic interaction between two point charges on a Cartesian grid.  For some reason, the answer key thought that one of the points had a negative y component, when it should have been positive.  I think I have manually given proper credit to all the answers.  Please let me know if I missed yours.

In Standard 15 Retest 1, I had to hand grade Question 2, because Canvas and I have different ideas of how “select all” questions should be graded. At any rate, the listed points at which the electric field is in the ↑ direction are a and i.

Standard 16 Retest 1 was an attempt to step you through a Gauss's law problem with a multiple choice quiz.  Now that you have the opportunity to look through it without any time or grade pressure, please do look through the questions (and look into the logical journey the quiz is trying to guide you along) to make sense of it.  If you still have questions, please contact me; I'd love to go over it.  And my mind is awhirl with questions of how to better quiz you on Gauss's law.

I had to hand grade Question 2 of Standard 17 Retest 1, because I can't anticipate every correct answer you might give me.  If you think you should have gotten more credit for your answer, tell me why.  I may come around.  I had to override the grades for Question 4, because the answer key's answers were too low by a factor of ten.  Oops.  Let me know if I missed yours.  I think I corrected the question for the next time I use it.

Standards

The criteria for satisfying the standards are explained in the table below.

Standard	Quiz	Questions	Points	Cutoff
2	Standard 2 Retest 3	2, 3	2	2
3	Standard 3 Retest 3	2, 3	2	2
4	Standard 4 Retest 3	2–4	3	2.5
5	Standard 5 Retest 3	2–6	10	9
6	Standard 6 Retest 3	2, 3	2	2
7	Standard 7 Retest 2	2–4	3	3
8	Standard 8 Retest 2	2–4	3	3
9	Standard 9 Retest 2	2–9	34	30
10	Standard 10 Retest 2	2–26	25	21
11	Standard 11 Retest 2	2–4	10	8
12	Standard 12 Retest 2	2, 3	2	1.8
13	Standard 13 Retest 1	2–10	12	10
14	Standard 14 Retest 1	2–6	7	5.8
15	Standard 15 Retest 1	2, 3	4	3
16	Standard 16 Retest 1	2–15	14	11
17	Standard 17 Retest 1	2–4	7	6
18	Standard 18 Retest 1	2–4	4	3.8
19	Standard 19 Retest 1	2–6	7	5.8

If you think anything was graded inconsistently or in error, let me know.  I want you to be credited for what you understand.  Also, if you have questions about any of the retests, please contact me and I'll be happy to review.  I don't think I'll be able to post detailed solutions to these.