Astronomy quiz question: distance of 61 Ursae Majoris from apparent and absolute magnitudes

Astronomy 210 Quiz 5, spring semester 2016
Cuesta College, San Luis Obispo, CA

61 Ursae Majoris is a star with an apparent magnitude of m = +5.3, and an absolute magnitude M of +5.4. 61 Ursae Majoris is located __________ 10 parsecs from Earth.
(A) farther than 10 parsecs.
(B) exactly 10 parsecs.
(C) closer than 10 parsecs.
(D) (Not enough information is given.)

Correct answer (highlight to unhide): (C)

61 Ursae Majoris appears to be +5.3 as seen from its true distance from Earth, but when placed at the "fair" distance of 10 parsecs away, its becomes slightly dimmer (+5.4). Thus it was pushed back just a little farther away from Earth when moved to 10 parsecs, and was located just a little closer than 10 parsecs away from Earth.

Section 30676
Exam code: quiz05sPrB
(A) : 18 students
(B) : 2 students
(C) : 30 students
(D) : 0 students

Success level: 62% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.57

Astronomy quiz question: distance of Arcturus from apparent and absolute magnitudes

Astronomy 210 Quiz 5, spring semester 2016
Cuesta College, San Luis Obispo, CA

Arcturus is a star with an apparent magnitude of m = –0.05, and an absolute magnitude M of –0.30. Arcturus is located __________ 10 parsecs from Earth.
(A) farther than 10 parsecs.
(B) exactly 10 parsecs.
(C) closer than 10 parsecs.
(D) (Not enough information is given.)

Correct answer (highlight to unhide): (A)

Arcturus appears to be –0.05 as seen from its true distance from Earth, but when placed at the "fair" distance of 10 parsecs away, its becomes slightly brighter (–0.30). Thus it was brought just a little closer to Earth when moved to 10 parsecs, and was located just a little farther than 10 parsecs away from Earth.

Section 30674
Exam code: quiz05nUL7
(A) : 10 students
(B) : 0 students
(C) : 8 students
(D) : 1 student

Success level: 48% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.80

Astronomy quiz question: changing apparent and/or absolute magnitudes of Groombridge 1618

Astronomy 210 Quiz 5, spring semester 2016
Cuesta College, San Luis Obispo, CA

Groombridge 1618 is a star that is located 4.87 parsecs away from Earth. If Groombridge 1618 were moved to a location 10 parsecs away from Earth, its apparent magnitude m would __________, while its absolute magnitude M would __________.
(A) get dimmer; not change.
(B) get brighter; not change.
(C) not change; get dimmer.
(D) not change; get brighter.

Correct answer (highlight to unhide): (A)

The apparent magnitude of Groombridge 1618, which is the brightness as seen from Earth, will get dimmer as it is moved farther away from 4.87 parsecs to 10 parsecs. The absolute magnitude, which is the intrinsic brightness, will remain the same no matter where Groombridge 1618 is located.

Section 30674
Exam code: quiz05nUL7
(A) : 12 students
(B) : 2 students
(C) : 3 students
(D) : 2 students

Success level: 64% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 1.0

Astronomy quiz question: changing apparent and/or absolute magnitudes of La Superba

Astronomy 210 Quiz 5, spring semester 2016
Cuesta College, San Luis Obispo, CA

La Superba is a star that is located 320 parsecs away from Earth. If La Superba were moved to a location 10 parsecs away from Earth, its apparent magnitude m would __________, while its absolute magnitude M would __________.
(A) get dimmer; not change.
(B) get brighter; not change.
(C) not change; get dimmer.
(D) not change; get brighter.

Correct answer (highlight to unhide): (B)

The apparent magnitude of La Superba, which is the brightness as seen from Earth, will get brighter as it is moved closer from 320 parsecs to 10 parsecs. The absolute magnitude, which is the intrinsic brightness, will remain the same no matter where La Superba is located.

Section 30676
Exam code: quiz05sPrB
(A) : 4 students
(B) : 41 students
(C) : 1 student
(D) : 5 students

Success level: 81% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.32

Astronomy quiz question: hottest star?

Astronomy 210 Quiz 5, spring semester 2016
Cuesta College, San Luis Obispo, CA

Which star is the hottest?
(A) A0 white dwarf.
(B) M0 red dwarf.
(C) G5 main-sequence star.
(D) B5 main-sequence star.
(E) (There is a tie.)

Correct answer (highlight to unhide): (A)

An H-R diagram is provided with this quiz.


Using the OBAFGKM spectral type mnemonic, or reading off of an H-R diagram (provided on this quiz, as below), the B5 main-sequence star is the hottest star, followed by the A0 white dwarf, then the G5 main-sequence star, while the M0 red dwarf is the coolest.


Section 30674
Exam code: quiz05nUL7
(A) : 2 students
(B) : 1 student
(C) : 3 students
(D) : 15 students
(E) : 0 students

Success level: 70% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.35

Astronomy quiz question: smallest star?

Astronomy 210 Quiz 5, spring semester 2016
Cuesta College, San Luis Obispo, CA

Which star is the smallest?
(A) A0 white dwarf.
(B) M0 red dwarf.
(C) G5 main-sequence star.
(D) B5 main-sequence star.
(E) (There is a tie.)

Correct answer (highlight to unhide): (A)

An H-R diagram is provided with this quiz.


These stars are plotted on an H-R diagram below. The A0 white dwarf is the smallest star, followed by the M0 red dwarf, then the G5 main-sequence star, while the B5 main-sequence star is the largest.


Section 30676
Exam code: quiz05sPrB
(A) : 27 students
(B) : 5 students
(C) : 3 students
(D) : 5 students
(E) : 11 students

Success level: 54% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.79

Astronomy quiz question: same-size supergiant vs. giant

Astronomy 210 Quiz 5, spring semester 2016
Cuesta College, San Luis Obispo, CA

A supergiant will be ___________ compared to a giant that has the same size.
(A) cooler and dimmer.
(B) cooler and brighter.
(C) hotter and dimmer.
(D) hotter and brighter.

Correct answer (highlight to unhide): (D)

An H-R diagram is provided with this quiz.


These stars are plotted on an H-R diagram below. The supergiant has a hotter temperature and a brighter luminosity than the main-sequence star, in order for them to have the same size.


The entries for the "box method" of comparing relative Stefan-Boltzmann parameters are listed below.

	Lum.	=	size	×	Temp.4
supergiant	↑		=		↑
giant	↓		=		↓

Section 30674
Exam code: quiz05nUL7
(A) : 1 student
(B) : 3 students
(C) : 2 students
(D) : 13 students

Success level: 70% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.80

Section 30676
Exam code: quiz05sPrB
(A) : 4 students
(B) : 3 students
(C) : 1 student
(D) : 43 students

Success level: 85% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.24

Astronomy quiz archive: sun/spectra/star properties

Astronomy 210 Quiz 5, spring semester 2016
Cuesta College, San Luis Obispo, CA

Section 30674, version 1
Exam code: quiz05nUL7


Section 30674

0- 8.0   :
8.5-16.0 :	*** [low = 12.0]
16.5-24.0 :	*******
24.5-32.0 :	** [mean = 25.9 +/- 8.8]
32.5-40.0 :	******* [high = 40.0]

Section 30676, version 1
Exam code: quiz05sPrB


Section 30676

0- 8.0 :	* [low = 8.0]
8.5-16.0 :	****
16.5-24.0 :	************
24.5-32.0 :	******************* [mean = 27.5 +/- 7.3]
32.5-40.0 :	*************** [high = 40.0]

Online reading assignment: fusion, nebulae, star cluster ages (SLO campus)

Astronomy 210, spring semester 2016
Cuesta College, San Luis Obispo, CA

Students have a weekly online reading assignment (hosted by SurveyMonkey.com), where they answer questions based on reading their textbook, material covered in previous lectures, opinion questions, and/or asking (anonymous) questions or making (anonymous) comments. Full credit is given for completing the online reading assignment before next week's lecture, regardless if whether their answers are correct/incorrect. Selected results/questions/comments are addressed by the instructor at the start of the following lecture.

The following questions were asked on reading textbook chapters and previewing presentations on fusion, nebulae, and star cluster ages.


Selected/edited responses are given below.

Describe something you found interesting from the assigned textbook reading or presentation preview, and explain why this was personally interesting for you.

"Molecular clouds because not only are new stars are born, but the dust can form planets. This is cool."

"I thought the cheerleader analogy was interesting!"

"That there are only three colors in space."

"How the more pressure there is within a star increase the fusion rate, which thus makes the star brighter and more luminous. I found this interesting because I never really knew what 'fusion' meant."

"Giants and supergiants having a very low-density--I would have expected something big to be more dense."

"That small stars have a longer life span than big stars--I thought it would be the other way around."

"Comparing the stars to people going to a house party."

"I found it interesting how fusion increases as heat and pressure increase. I had always wondered what causes fusion to occur."

"The lifetimes of the stars, and why they die."

"Why different sizes of stars have different luminosities."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.

"The different types of nebula. How do we tell the difference?

"I don't understand why white dwarfs don't relate to the same rules about mass and luminosity as main-sequence stars."

"Learning about nebulas because I didn't really know what they were or what the colors meant."

"Layers in the hydrostatic equilibrium had me a little lost."

"Why clouds of hydrogen emit a pink color. This is because I don't understand the nature of light and hydrogen."

"That some stars obey the mass-luminosity rule, while others don't, because it seems like there's a lot of exceptions to these rules we learn."

"The evolutionary tracks of different stars are a bit confusing just because there is so much going on!"

"I did't find things that complicated this time. This was pretty informative and went straight to the point."

"Pretty much all of it this time."

Rank the luminosities of these main-sequence stars (1 = brightest, 3 = dimmest). (There are no ties.)
(Only correct responses shown.)

Massive: brightest luminosity [96%]
Medium-mass (sunlike): medium luminosity [100%]
Low mass (red dwarf): dimmest luminosity [96%]

Rank the fusion rates of these main-sequence stars (1 = fastest, 3 = slowest). (There are no ties.)
(Only correct responses shown.)

Massive: fastest fusion rate [83%]
Medium-mass (sunlike): medium fusion rate [96%]
Low mass (red dwarf): slowest fusion rate [88%]

Fusion requires high temperatures in order for nuclei to move quickly enough to:

break heavy elements apart.	**** [4]
create convection currents.	** [2]
overcome gravity.	***** [5]
overcome repulsion.	********************************* [33]
(Unsure/guessing/lost/help!)	**** [4]

Briefly explain why "cold fusion" (producing energy from hydrogen fusion at room temperature) would be implausible.

"Cold fusion is implausible because fusion can only happen under extreme temperatures and high pressure."

"The protons wouldn't move fast enough to be able to bump into each other."

"High temperature is required to force protons to collide and produce energy. At room temperature, protons hate each other like Taylor Swift and Kanye." #immaletyoufinish

Match the three different types of nebulae with their colors.
(Only correct responses shown.)

Emission: pink [81%]
Reflection: blue [85%]
Dark: brown/black [90%]

Match the three different types of nebulae with their composition.
(Only correct responses shown.)

Emission: hydrogen [90%]
Reflection: small dust particles [85%]
Dark: large dust particles [88%]

Rank the lifetimes of these main-sequence stars (1 = shortest, 3 = longest). (There are no ties.)
(Only correct responses shown.)

Massive: shortest main-sequence lifetime [71%]
Medium-mass (sunlike): medium main-sequence lifetime [96%]
Low mass (red dwarf): longest main-sequence lifetime [73%]

If there was an open invitation to a house party (no specific time given), when would you show up?

Early, or on time.	************ [12]
When the most people should be there.	************************************ [36]
After most everyone has left.	[0]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"How have we learned everything we know about about stars--they are so far away? Like, how do we know their composition?" (We know what stars are made of from analyzing the absorption lines in their spectra. Their colors tell us their temperatures, their parallaxes tell us their distances, and we can also calculate their sizes as well.)

"How does fusion have an effect on a star's luminosity?" (For main-sequence stars, its luminosity (bright or dim) is related to the rate of energy released by fusion in their cores (rapid or slow).)

"I found the stars that do not obey the cheerleader model [supergiants, giants, and white dwarfs] a bit confusing. How does the mass not affect their luminosities?" (All main-sequence stars (massive, medium-mass, and low mass) produce energy by fusing hydrogen, but at different rates related their masses. Supergiants, giants, and white dwarfs are actually stars that have used up their hydrogen, so they are either dying or dead, so their masses don't relate to their rate of energy production.)

"All of the examples for this section were awesome! I love the nebula photos because they are so pretty and intriguing to stare at. But I also love the house party because the analogy is funny and totally helped me understand!"

"Yes, I would come to your awesome house party. I would arrive early and stay late." (Keep in mind that the house party is just an analogy for different star lifetimes.)

"When is the house party? I'll bring chips and salsa." (The chips and salsa are an analogy for what, exactly?)

"When do you show up to parties? Early, on time, when most people are there or when mostly everyone has left?" (I am always late, but worth the wait. #youshouldbehonoredbymylateness)

Online reading assignment: advanced electricity (review)

Physics 205B, spring semester 2016
Cuesta College, San Luis Obispo, CA

Students have a bi-weekly online reading assignment (hosted by SurveyMonkey.com), where they answer questions based on reading their textbook, material covered in previous lectures, opinion questions, and/or asking (anonymous) questions or making (anonymous) comments. Full credit is given for completing the online reading assignment before next week's lecture, regardless if whether their answers are correct/incorrect. Selected results/questions/comments are addressed by the instructor at the start of the following lecture.

The following questions were asked on re-reading textbook chapters and reviewing presentations on advanced electricity concepts.


Selected/edited responses are given below.

Describe what you understand from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically demonstrate your level of understanding.

"Some of it, but it gets confusing. I think I need to look at more specific instances."

"The differences between series and parallel. I just need to review the different equations and such."

"Learning a little more about what makes an ammeter. I found it interesting to read the advanced electricity blog and learn more about every day electricity such as household electricity."

"Ammeters have zero internal resistance, making them dangerous if you wire them into a circuit wrong. The circuit should be 'broken' and the ammeter wired into the gap; connecting it in parallel can cause an unsafe rise in current. Voltmeters can be used to measure the voltage drop/rise across any two points."

"Same good ol' electricity. Don't want too much power going through parallel circuits which is why you have a circuit breaker just in case. [Series] resistance adds up, and you don't want to mess up multimeter readings due to improper placements."

"An ammeter measures current flow and must have zero resistance to not change the circuit it is measuring. A voltmeter simply gives you the pressure difference between any two points and the voltmeter has infinity resistance."

"Placing more resistors lined in-parallel within a circuit will result in a greater chance of accumulating a runaway current. It took me the lab as well as reading to sort of visually see how current can steadily build within a circuit as its resistors are placed in parallel. The spread of current allows for the possibility of there being less potential drop in electric potential energy as current travels through each given resistor in parallel."

Describe what you found confusing from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically identify the concept(s) that you do not understand.

" Kirchhoff's rules are a little fuzzy to me but I just have to do some more example problems to fully understand them."

"I still just find resistors and ammeters confusing. Maybe they aren't as complicated and I am making it more complicated than it really is. I just need to go over equations and really get a solid feel for it."

"I'm kind of lost on the application of bulbs and switches, etc."

"Why resistance goes to infinity for a dead battery, or for a burnt-out light bulb."

"I am confused on everything!"

"Nothing particularly."

What are the resistances of these (ideal) devices?
(Only correct responses shown.)

Ideal light bulb: some finite value between 0 and ∞ [65%]
Burnt-out light bulb: ∞ [36%]
Ideal wire: 0 [55%]
Ideal (non-dead) battery: 0 [39%]
Real (non-dead) battery: some finite value between 0 and ∞ [74%]
Ideal switch, when open: ∞ [48%]
Ideal switch, when closed: 0 [48%]

Two light bulbs with different resistances r and R, where r < R, are connected in series with each other to an ideal emf source. Select the light bulb with the greater quantity.
(Only correct responses shown.)

More current flowing through it: (there is a tie) [52%]
Larger potential potential difference: light bulb R [55%]
More power used: light bulb R [29%]

Two light bulbs with different resistances r and R, where r < R, are connected in parallel with each other to an ideal emf source. Select the light bulb with the greater quantity.
(Only correct responses shown.)

More current flowing through it: light bulb r [35%]
Larger potential potential difference: (there is a tie) [35%]
More power used: light bulb r [16%]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"I appreciate the fact that you had our midterm right before Easter so that our holiday was free and how you're having our quiz this Friday so that our spring break is free. Thank you!" (Thereby ruining my Easter and my spring break. #yourewelcome.)

"This was really confusing!"

"Twinkle twinkle....dang it!"

"I suck at physics. It's ruining my self-esteem."

"Don't April fools me with the quiz. #notcool"

"How can we determine the resistance of certain [ideal/real/burnt out] devices? I'm not sure how to go about evaluating things." (We'll go over these on the worksheets in class.)

Online reading assignment: fusion, nebulae, star cluster ages (NC campus)

Astronomy 210, spring semester 2016
Cuesta College, San Luis Obispo, CA

Students have a weekly online reading assignment (hosted by SurveyMonkey.com), where they answer questions based on reading their textbook, material covered in previous lectures, opinion questions, and/or asking (anonymous) questions or making (anonymous) comments. Full credit is given for completing the online reading assignment before next week's lecture, regardless if whether their answers are correct/incorrect. Selected results/questions/comments are addressed by the instructor at the start of the following lecture.

The following questions were asked on reading textbook chapters and previewing presentations on fusion, nebulae, and star cluster ages.


Selected/edited responses are given below.

Describe something you found interesting from the assigned textbook reading or presentation preview, and explain why this was personally interesting for you.

"This might not be considered interesting, but the different nebula colors are pretty cool. It's crazy what goes up there."

"The nebulae and the causes of their different colors."

"The H-R diagram--I just wish I knew how to use it."

"How the colors red and blue mean the opposite of what we are used to. Hot and cold."

"That you can use stellar luminosities to determine the diameters of the stars."

"I enjoyed learning about some of the nebulas. It was cool to learn about how they are made and why the appear to be the colors that they are."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.

"Cold fusion--I don't know where to even start."

"The whole fusion thing was a little confusing."

"Some aspects of fusion were confusing for me."

"The difference between the different nebulae."

"I'm not really sure if there was anything I found confusing."

Rank the luminosities of these main-sequence stars (1 = brightest, 3 = dimmest). (There are no ties.)
(Only correct responses shown.)

Massive: brightest luminosity [83%]
Medium-mass (sunlike): medium luminosity [83%]
Low mass (red dwarf): dimmest luminosity [100%]

Rank the fusion rates of these main-sequence stars (1 = fastest, 3 = slowest). (There are no ties.)
(Only correct responses shown.)

Massive: fastest fusion rate [67%]
Medium-mass (sunlike): medium fusion rate [83%]
Low mass (red dwarf): slowest fusion rate [75%]

Fusion requires high temperatures in order for nuclei to move quickly enough to:

break heavy elements apart.	** [2]
create convection currents.	* [1]
overcome gravity.	* [1]
overcome repulsion.	**** [4]
(Unsure/guessing/lost/help!)	**** [4]

Briefly explain why "cold fusion" (producing energy from hydrogen fusion at room temperature) would be implausible.

"It wouldn't cause the protons to move fast enough and collide."

"In order for fusion to actually happen, you need heat. Because heat is what makes the atoms move at a faster rate. otherwise they won't fuse together."

"Without the presence of high heat, the nuclei would not have enough speed to cause the violent collisions necessary to cause the needed reactions."

"I don't know."

Match the three different types of nebulae with their colors.
(Only correct responses shown.)

Emission: pink [67%]
Reflection: blue [67%]
Dark: brown/black [75%]

Match the three different types of nebulae with their composition.
(Only correct responses shown.)

Emission: hydrogen [67%]
Reflection: small dust particles [75%]
Dark: large dust particles [83%]

Rank the lifetimes of these main-sequence stars (1 = shortest, 3 = longest). (There are no ties.)
(Only correct responses shown.)

Massive: shortest main-sequence lifetime [75%]
Medium-mass (sunlike): medium main-sequence lifetime [83%]
Low mass (red dwarf): longest main-sequence lifetime [75%]

If there was an open invitation to a house party (no specific time given), when would you show up?

Early, or on time.	***** [5]
When the most people should be there.	****** [6]
After most everyone has left.	* [1]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"Wikipedia helps." (Wikipedia don't lie.^{[citation needed]})

"I'm in a cabin trying to not lose more points in your class." (A Cabin...in the Woods?)

"What you taught us [Stefan-Boltzmann law] on Thursday made so much sense, I actually understood it!"

"Everyone loves a good house party."

"I'm that person that always arrives awkwardly late to house parties. Not intentional. Just always happens." (Always late, but worth the wait, right?)

Online reading assignment question: keep, quit, start

Astronomy 210, spring semester 2016
Cuesta College, San Luis Obispo, CA

"160328Astr210-keep"
flic.kr/p/FJiBZy
Waifer X

Wordle.net tag cloud for "keep" resolutions generated by responses from Astronomy 210 students at Cuesta College, San Luis Obispo, CA, spring semester 2016.


"160328Astr210-quit"
flic.kr/p/FEJtK6
Waifer X

Wordle.net tag cloud for "quit" resolutions generated by responses from Astronomy 210 students at Cuesta College, San Luis Obispo, CA, spring semester 2016).


"160328Astr210-start"
flic.kr/p/FCqiTw
Waifer X

Wordle.net tag cloud for "start" resolutions generated by responses from Astronomy 210 students at Cuesta College, San Luis Obispo, CA, spring semester 2016.

Students were asked to answer a "keep-quit-start" online reflection (hosted by SurveyMonkey.com) on their studying strategies/pitfalls (Mubayiwa, 2009).

Enter a word or brief phrase that describes what you intend to keep doing to study for this class. Explain your answer to the above question (what you intend to keep doing to study for this class).

Enter a word or brief phrase that describes what you intend to quit doing to study for this class. Explain your answer to the above question (what you intend to quit doing to study for this class).

Enter a word or brief phrase that describes what you intend to start doing to study for this class. Explain your answer to the above question (what you intend to start doing to study for this class).

[Word tags have been edited to consolidate related common subjects; student explanations are verbatim.]

Keep word tags:

gotoclass
      I am not doing well at self-taught Astronomy, but coming to class, hearing the lecture and being able to ask questions really helps solidify my understanding of key concepts.
      I will continue to come to class and do the homework. These are easy points and help clarify things.
      The class pre-work is helpful but the concepts don't come together until the in-class exercises.
      I will keep attending the classes, studying for tests/quizzes, and doing surveys/in class assignments
      Most of the points in this class it seems are based off of classwork or things done in class. (this includes quizzes) Also the lectures have helped me understand everything that we have read about on out own
      I will plan to keep study for quizzes and also attending class to make sure i receive all points possible for in class activities.
      I want to keep being present in class to receive the most knowledge from you as I can. I find being in class and having you explain things clicks more in my brain than reading the assignments.
      I intend to keep attending classes frequently in order to better understand the material.
      Even though its hard to motivate myself to come back to Cuesta every Wednesday night, especially with spring break and summer right around the corner, I need to make sure I keep my attendance up because its hard for me to learn and understand everything by self teaching and hearing the lecture helps for clarification.
      By going to class every single time, I am getting class points [worksheets] that I wouldn't get if I didn't go. That's 100 points right there and at the rate I'm going, I'm going to need every point I can get. being there is the best way to keep from getting zeros and with my grade so far I need to be there
      Continuously attending the lecture class helps clarify any confusing material from the reading assignments, and it helps me retain the information better.
      Attending class is the most important because P-Dog goes over info that's ridiculously confusing sometimes.
      Don't miss any classes and do all the reading assignments and in class activities.
      Interacting helps learn the material better
      When I focus in class I am able to absorb topics better.

homework
      I had previously said that completing all assignments, and I think its important because it helps understand everything that we are learning and we also get credit for completing them.
      I need to do the homework before it's due and read it in depth and take notes
      I need to keep up on the weekly reading assignments and make sure that I fully understand the concepts. I was a little behind as far as understanding everything before the midterm and had to cram to understand everything. If I stay on track and keep myself interested and in tune with the topics at hand it will be a lot easier to succeed in class.
      The homework assignments make sure that you read the blog for the upcoming class and count for more points then we think when they're added all up at the end of the course and they don't take a lot of time.
      I realize that the homework and classwork are worth not only worth a lot of points, they also help me understand the material better. Doing the homework and in class assignments is smart because I can accumulate points and test prep at the same time.
      Completing the online assignments really helps me understand the material being taught in class. If I keep this up it will result in higher test and quiz scores, as well as points from doing the surveys themselves.

learning
      P-dog is a great teacher. It all makes sense when he explains it. It's when he stops talking that I get lost. But I'm starting to get the hang of things on my own. I still need his help every now and then, but overall, I think I need to keep on learning by myself so that I can be more independent.

read
      I have been doing a very good job at completing the weekly readings and the quiz that follows. Along with attending class. I know that the weekly readings help because I'm able to understand the material a little better. And if you don't go to class you miss a lot more material. It all adds up quickly. And if you miss anything you pay the price.
      I did not had a lot of time to read the material over the past ten weeks due to an extremely difficult Math course. Now I have more time to dedicate to read and understand the material.
      I intend to stay focused and continue reading the reading assignments to do better in the class.
      I've always had trouble keeping up with the reading in classes and suffered for it. However, in this class I've been able to keep up with it and it's helped. I am going to keep reading the chapters assigned for every class to succeed in this class.
      I noticed that just previewing the online presentations (which I previously did) did not help a lot because I didn't own a textbook, but when using the textbook in the library and reading the material alongside with the online presentations, I realized that I understood the material better and was able to apply what I learned from both the textbook and presentations onto the in class activities.
      I feel like when I actually read the assigned chapters I do better in class, and I understand more of the in class assignments
      Well it'd be dumb to not read the notes provided for us. I will continue to read the textbook in this class.

review
      This helps me to know the material in test form as well as knowing what us important to know.
      going back through and re-reading the lectures was really helpful for me when I was studying for the midterm.
      I'm going to keep going over my old quizzes and practice quizzes to study for future exams.
      I want to keep on reviewing the practice quizzes we do in class and the ones that are available online. They help me understand what type of questions might be asked.

study
      I will continue to study as much as I can before each quiz or exam for the simple fact that if I don't I will do extremely worse on everything.
      You can never go wrong with too much studying.
      well i have not done well in my quizzes and i know if i study harder then i will do better on the quizzes. i have been getting lower then 12 on the quizzes and that has severely effected my grade. so the only way to pull my grade up is to do better on the quizzes.
      I spent a good amount of hours studying and reviewing for the midterm. I need to keep doing this, and do it more often.
      By studying I mean really working to understand concepts, not just memorizing information. This is what makes science so challenging but also rewarding
      Studying is a proven way to succeed in academics. Studying the quizzes and my notes have helped a lot.
      Make sure that when I have spare time in between classes or not going to work that I spend a satisfactory amount of time to learn what is necessary for this course by studying, instead of distracting myself with distractful activities.
      I plan to keep studying the material in order to succeed in this class! So far forming a study group with classmates has made a difference in my quiz scores and studying before class makes a difference as well. There was a significant difference in scores on a quiz I forgot to study for, compared to one I did study for. I do although plan on devoting more time to studying!
      I am going to continue studying the material.
      I study from the textbook before quizzes and tests and it seems to help a lot.

takenotes
      helps with reviewing instead of skimming a text on a whim
      I do the weekly reading in the book and take notes on the terms as I go in order to remember all of the information and to have another study technique. Notes help me a lot and always have; without them I would not be surviving what so ever in this class.

Quit word tags:

distractions
      I want to quit getting so distracted when I go to study for quizzes or midterms. I work so much that sometimes when I have the time to study, my mind can easily wonder off to something else. I need to focus on the schoolwork and just think about what I'm needing to learn and not what's going on at work or in my social life.
      Although I hate to admit it my phone has been a distraction to me in class. I find it hard to ignore a text for a whole two hours. I have noticed that my phone has kept me from being present in the moment and I plan on turning it off while I am in class! I know with just this simple device being shut off my focus and scores will improve in class.

forgethomework
I want the credits for the inline surveys, so I have to commit to memory that they must be done.

missingclass
      i've missed class a few times, and i need to stop missing class because i'm missing out on group work points.
      Things will keep me from attending class. I've lost my motivation to attend class. I've been attending college for two years straight. I've taken even the summer classes. I remember my first year. I was so eager to go to school. It felt like waking up to go to the first day of school every day. But I've lost my drive. Family and friends are also a big distraction. Throw in car problems and you've got the entire team together. I want to quit making/using excuses for not coming to class.
      I've only missed one class but especially since it's only one day a week it makes it hard to keep on track if you miss it.
      I do come to most classes, I think I've missed three, but they all happen to be classes before quizzes so I need to be present so I can prepare for quizzes and do better on them.
      Just missing one class can result in the loss of valuable information that could appear on a test. I'm going to try to quit the occasional absence in order to be as prepared as possible for examinations. Plus this maximizes participation points!

notcompleting
      I haven't done a great job completing reading assignments through out this class not totally completing the online assignments (mostly the sections about interests and questions)

notfollowingdirections
      After getting my mid-term back , I noticed that I had missed points on both the mid-term and the quizzes by not Xing the impossibilities as part of the directions on these tests. Can't believe I was so foolish to miss that and lose out on much needed points!

notfollowingup
      I have a tendency to only do the flash card questions I know or are easy to find in the text/lectures, and it is affected my quiz grades negatively.

notprioritizing
      I work 30 hours per week at a bank, I take 5 classes for 19 credits. I am extremely busy and quite often there is not enough hours in the day to stay caught up on my schooling. I do recognize that this class is not insignificant, and that I do need it as a grad requirement. I cannot keep putting my other classes before this class. well if you start failing in a class that your not going to pass, and you continue to try. that would be stupid because you will start failing in other classes that you could have passed.
      Sometimes, i am busy with the other stuffs and don't have enough time to study. I should make the planing schedule and follow it strictly.

notreading
      I prioritize my day classes because its a more normal schedule for me so I tend to forget to take time for this class. Plus I just hate reading textbooks. The information doesn't stay with me, but it would be more helpful.

notreviewing
      Sometimes I study for a quiz or test a week or so before the quiz/test. Before the day of the quiz/test I tend to forget to review the materials I had studied a long time ago and I end up forgetting some of the materials.

notstudying
      Not studying makes my quiz scores low

procrastinating
      I always wait until the last minute!
      I get frustrated rather quickly if I don't understand. And once I don't understand I either stall or give up. With some topics in this class I have a hard time understanding. With that being said once it gets close to test time I get frustrated when trying to study and end up giving up. I need to work on really applying myself. I know that I can do it it's just a matter of making myself do it. I learn a lot slower than my peers do and I need to spend much more time on topics. I guess my point here is that I need to make more time for myself to study. Even if that's in smaller intervals. I need to push myself to do better on tests and stop giving up on myself so quickly.
      I'm going to stop waiting until the latest moment to study for quizzes and exams.
      last minute preparation does not help me at all to be prepared really. bad habit.
      I need to do homework and study earlier than just the day before.
      Especially with the homework, I procrastinate until the last hour or so which typically leads to homework assignments not getting done.
      I will stop procrastinating to achieve a better grade in the class and learn more effectively about astronomy.
      Although I will continue to study, I want to stop procrastinating and only studying the night or few nights before, especially when it comes to the larger exams like midterms.
      i need to stop doing my homework late at night because that is effecting how much i actually spend on my homework .
      I think I just need to procrastinate less and prepare myself more than I usually do.
      Be more on top of my time management
      Waiting until the last moment hinders me because something always happens at the end which prevents me from getting it done.
      I have a bad habit of waiting till the day before class to start studying or reading. I need to start earlier and pace the amount of studying more evenly.
      I save a lot of my work for the night before or the day of and it doesn't leave time for me to ask questions and understand everything.
      I feel like it would be better if I did the readings earlier in the week.
      Stop waiting until the night before to do the homework for class
      Its easy to think you have more time. I want to do a better job at getting the assigned reading done on time.
      I'm going to stop waiting until the last day to study for quizzes.
      Since I tend to do the pre-assignments the night before it is due, I realized that I am unable to review a second time the material that could help ingrain that knowledge in my head deeper. By doing the assignments earlier and reviewing a day or two before the day of class, it might help my retention and do better with tests because of the constant repetition with the material.
      I plan on not waiting till the last minute to study, so i can do better on the quizzes and I plan on spending more time on the assigned readings.
      I want to quit waiting till the last minute to do online surveys and study.
      I intend to stop myself from procrastinating by making sure that over the weekend (the days I have no school or work) I do a combination of studying for tests/quizzes as well as doing the online assigned homework and readings.
      I intend to stop waiting till the last minute to study for quizzes and tests. Since we only meet once a week, I think that I'll have enough time to get it all in, but I always end up waiting until it's too late and it definitely shows on my quiz/test scores.
      I tend to put things off to the last minute and need to do a better job of getting ahead of the class like I'm used to because then I feel more confident in my work.
      I should space out the reading more through out the week, instead of reading all of it a couple of hours before class.

rushing
      I need to stop looking at homework assignments with the intent to get through them quickly. Real learning only takes place when I'm relaxed, focused and allowing myself to completely direct my attention to astronomy.

sittingintheback
      I have very bad vision and have no glasses so I can barely participate in class.

slacking
      I have to study every day in order to understand the weekly concepts, if I miss a day, I will forget the readings or confuse the concepts.

zoningout
      occasionally in class, I zone out and miss what was said.
      I need to try and focus more during our 3 hour class.

Start word tags:

askquestions
      Making sure that if I don't understand something or I'm confused about a concept to ask questions and understand fully before moving on. All the topics kind of lead off each other so it's hard to succeed if you can't understand the basics.
      I have been depending on what we learn in class too much. since its only once a week and its "flipped teaching" i need to do a lot more studying at home. I also need to start asking more questions, not getting them cleared up is adding up.
      Start finding confusions and interests in the reading
      I need to ask more questions when I don't understand concepts. I definitely have a fear of looking dumb so this is something I struggle with.
      If I get lost, I tend to try to figure it out myself rather than just asking for help
      I tend to not ask questions during class because of a big class and I end up just making a side note and looking up my question in the textbook or online when I get home. Also I think that when I don't ask questions in class, I feel like I'm not engaging as much as I should be.

droporquit
      time and space goes hand and hand. The universe seems to be expanding at an exponential rate, time is going faster and faster, so in my world it makes me feel like i'm getting slower. all the things i thought i can do quickly takes more time to do, and the time no longer exists.

earlier
      I need to not wait to the last minute to study the sections.
      Start them earlier in th week
      I'm hoping by spending a little more time studying and not waiting till the last minute, I am able to succeed and not be so stressed out about the class.

flashcardquestions
      I am going to start using flashcards and finishing the practice quizzes to broaden my studying techniques.
      Using the flashcards will help me decipher the important information I need to know understand the subject matter and pass tests and quizzes.
      I want to start to actually review all of the flashcards before quizzes and exams. I did this for the first couple quizzes and I did much better on them than the ones where I stopped reviewing the flashcards for.
      I have heard quite a few people talk about how helpful the flashcard questions are and I know I need to start utilizing this study tool.
      I need to start studying the flashcard questions more often and continue to go over them.

focusing
      I intend to make a conscious effort to really focus more in class. It is easy to get distracted with technology, other students, and other upcoming tests in other classes. I plan on starting to become more focused and in tune with the lectures to succeed!
      I plan to be more prepared for quizzes since they represent a decent portion of my grade. Also, it would be beneficial to take as many quizzes as possible to increase the likelihood of high chosen scores.
      Just like I mentioned above since I've been getting frustrated with the material I haven't been doing my best. So I ended up getting myself a tutor and we meet typically once sometimes twice a week to go over what we are learning in class. That has actually helped me more than I thought. And I'm finally feeling a little more comfortable. My hope is that now that I have a tutor I will now be starting to try more. And always be sure to study harder for tests and take my time really reviewing. I believe that I can do it now I just need to try harder in all areas and give myself time to really learn and understand the material.
      im always on my phone in class so i need to start putting away my phone until break unless im looking up something for the assignments. its effecting me not taking notes therefore i have little to study and understand anything.
      I need to improve as I go. I will make mistakes along the way. I'll take a C on the first quiz, but I strive to get an A on the next one. My goal is to only go up from here.

officehours
      I want to visit you in your office hours more to make sure I am on the right track.

onlineresources
      I have a really hard time thinking in this way so I am going to try a new angle and start trying to study even more in depth by watching more online videos and clips about each topic so I hopefully will start to understand.

practicequizzes
      I will start looking online and work on practice questions and "reviews" to do better.
      Take the practice quizzes more than once or twice before tests and quizzes.

reading
      reading the textbook ahead of time will give me an idea as to what will be discussed in class instead of learning it right then and there.
      I usually just read the online notes, and they're very helpful. But i'd gain a better understanding of the material if i read the textbook as well.
      I always skim over the assigned reading chapters, but I don't always read it thoroughly. I need to start reading all assigned book chapters thoroughly.
      I've been mainly reading only the online presentations and not so much the assigned book, although it didn't hinder my test score this time it has somewhat hindered my quiz scores, by devoting my weekend (free time) to reading the book I should be better able to succeed in this class.
      I should start reading ahead off time. Right after the class is best and keep reading. Ask to help if I don't understand or stuck.

reviewing
      Like I said before, I don't review sometimes before a quiz/test and that's one of my weaknesses. I will start reviewing from now on.

studygroups
      Throughout my three years here at Cuesta I have learned that study groups are one of the most beneficial ways of learning knew material. I plan to make sure we meet up a few times before the next exam.
      I have made arrangements with some classmates to start a study group, its always better to have more than one brain working together. It will also help to be able to ask question that maybe i don't understand and some one in the study group does.

studying
      Start studying to get better grades on the quizzes
      I need to start putting in more time to study and prepare for classes
      Spending more time on the topics to get a better understanding of the material.BR>       My quiz scores are just awful and its important that I do well on the next 5.
      I don't really understand this class, so i need to study a little harder to be able to get a better grade.
      I don't make nearly enough time to study, and restudy the previous learned subjects. I don't spend enough time between tests reviewing and rereading.
      I always study for any sort of quiz or exam but recently I have noticed that my method is not working as it usually does, therefore I think I need to start preparing more days and probably will not do the study groups because it didn't really help me.
      that way I don't have to cram right before the next big test
      I plan on studying more than i have been in order to get the grade i want to receive.
      I want to start studying more and being more determined to learn the material.
      I do study but I could definitely do it more!

takenotes
      I want to start taking better notes from classroom discussions so that I can use them to study.
      I do the reading each week, but it sometimes seems to go over my head. I need to start writing notes or highlighting in order to fully grasp the material.
      I think taking notes from the chapters in the book would be helpful in retaining some of the information, and it would help me to remember what parts of the reading were confusing so that I could clarify that better in class.
      I suck at taking notes as it is and being towards the back of the class isn't helping my case. If I sit closer to the front, I can take better notes.

Online reading assignment: advanced electricity

Physics 205B, spring semester 2016
Cuesta College, San Luis Obispo, CA

Students have a bi-weekly online reading assignment (hosted by SurveyMonkey.com), where they answer questions based on reading their textbook, material covered in previous lectures, opinion questions, and/or asking (anonymous) questions or making (anonymous) comments. Full credit is given for completing the online reading assignment before next week's lecture, regardless if whether their answers are correct/incorrect. Selected results/questions/comments are addressed by the instructor at the start of the following lecture.

The following questions were asked on reading textbook chapters and reviewing presentations on circuit analysis and previewing presentations on advanced electricity concepts.


Selected/edited responses are given below.

Describe what you understand from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically demonstrate your level of understanding.

"Power is the rate of electrical potential energy used per time. Electrical outlets in a house are wired in parallel so that each appliance you plug in receives the same amount of voltage, but this can also be dangerous because the more appliances you plug in the lower the equivalent resistance becomes. If the resistance gets to low, the increased current can cause damage."

"The proper way to set up the instruments provided to us in lab, and the importance in making sure we connect everything properly. I also understand power dissipation."

"When measuring passing current through a circuit into a bulb the current flowing needs to be broken so it can be measured with a multimeter."

"When measuring the current passing through a light bulb the current that passes through the light bulb must also pass through the digital multimeter,and when measuring electrical potential used by a light bulb, the digital multimeter must be connected to both before and the current flows."

"To measure electric potential, we have to take the measurement before and after the current goes through the source(bulb). To measure currents, the current also has to go through the multimeter. circuit breakers are used to trip when a current is too large, to avoid runaway current from melting the insulated wire and cause a fire."

Describe what you found confusing from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically identify the concept(s) that you do not understand.

"The concept of potential drops in the loop rule is a little confusing to me. I also don't know when to use the junction rule."

"I don't understand what power dissipation is or how it is useful. I tried reading in the book ,but I was just really confused."

"There's nothing that I really find confusing."

"I find some of the theories confusing along the way but I know that with more practice I will be able to do better on these types of circuit problems. I am still weak on my vocabulary as well so I need to work on that."

"Why an ammeter has to have a very low resistance and why a voltmeter's resistance should be very large."

What are the resistances of these (ideal) devices?
(Only correct responses shown.)

Ideal ammeter: 0 [69%]
Ideal voltmeter: ∞ [67%]

State the unit of electrical power, and give an equivalent definition in terms of other SI units.

"Watts, or joules per second."

"Volts."

"Amps."

"Unsure."

"Watts or amps? I'm not quite sure."

"Electric power is P = I·∆V, and the units for this equation is the watt, or one joule per second."

Determine what will happen to the following parameters when additional electrical appliances are plugged in and turned on in the same household circuit.
(Only correct responses shown.)

Equivalent resistance R_eq of circuit: decreases [54%]
Current I flowing through emf source: increases [52%]

A fuse or circuit breaker is designed to prevent too much __________ in household wiring.

current.	********************** [22]
voltage.	** [2]
(Both of the above choices.)	* [1]
(Neither of the above choices.)	[0]
(Unsure/guessing/lost/help!)	*** [3]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"I want to see what my grade for the midterm was. Super scared!"

"Happy Easter ????"

"Hope the midterms weren't too hard to grade! Meaning that we did well...good job guys!!!"

"I've been studying calculus and biology all weekend. Two tests Thursday. Eat, sleep, pray, calc, pray and do calc in the middle of prayer, bio, repeat."

"Can we please go over the difference between voltage and current again?? I'm still really shaky on that."

"What is the different between amps and volts. is it simply that amps are per second and volts is just the amount of current at a given time?" (Amps is the amount of current, or charges per second, flowing through a wire. Volts is the amount of potential, which measures how much energy each and every (unit) charge carries as they flow through a wire. So essentially, amps is how much "stuff" is flowing through a pipe, while volts is how much "push" is contained in the stuff flowing through a pipe.)

Physics midterm question: reception from an electric dipole antenna

Physics 205B Midterm 1, spring semester 2016
Cuesta College, San Luis Obispo, CA

A radio transmitter broadcasts using a horizontal electric dipole antenna mounted along the north-south direction. A Physics 205B student holding a vertical receiver is located to the west of the transmitter, and walks to the south of the transmitter. Discuss whether the signal (if any) received by the Physics 205B student will increase, decrease, or not change as she walks from west to south. Explain your reasoning using the properties of light and polarization.

Solution and grading rubric:

• p:
  Correct. Discusses/demonstrates that no signal will be received by the Physics 205B student's vertical receiving antenna as she walks from west of to the south of the horizontal north-south transmitting antenna because:
  1. her vertical antenna cannot receive a horizontally polarized radio signal emitted by the transmitting antenna to the west, and;
  2. the transmitting antenna does not broadcast any signal to the south, along its antenna axis.
• r:
  As (p), but argument indirectly, weakly, or only by definition supports the statement to be proven, or has minor inconsistencies or loopholes. Typically only explanation for (1) is complete, but not (2).
• t:
  Nearly correct, but argument has conceptual errors, or is incomplete. Typically only explanation for (2) is complete, but not (1).
• v:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Some garbled attempt at applying the properties of light (radio waves) and polarization.
• x:
  Implementation/application of ideas, but credit given for effort rather than merit. No clear attempt at applying the properties of light (radio waves) and polarization.
• y:
  Irrelevant discussion/effectively blank.
• z:
  Blank.
  

Grading distribution:
Sections 30882, 30883
Exam code: midterm01rx1C
p: 25 students
r: 8 students
t: 8 students
v: 2 students
x: 0 students
y: 0 students
z: 0 student

A sample "p" response (from student 2468):
A sample "t" response (from student 0558):

Physics midterm question: comparing converging lens image sizes

Physics 205B Midterm 1, spring semester 2016
Cuesta College, San Luis Obispo, CA

An object is placed 20 cm in front of a f = +5.0 cm converging lens, which produces an image. When the object then placed 10 cm in front of this lens, discuss why this image is not twice as large as the previous image. Explain your reasoning by using ray tracings and/or thin lens equations, the properties of lenses, images, and magnification.

Solution and grading rubric:

• p:
  Correct. Discusses/demonstrates that the image (or linear magnification) produced by the object 10 cm in front of the lens is not twice the image (or linear magnification) produced the same object placed 20 in front of the lens from:
  1. calculating the image distances produced by the different object distances, and finds the resulting respective image sizes or linear magnification factors, or;
  2. drawing two carefully, properly scaled ray tracing diagrams.
• r:
  As (p), but argument indirectly, weakly, or only by definition supports the statement to be proven, or has minor inconsistencies or loopholes.
• t:
  Nearly correct, but argument has conceptual errors, or is incomplete.
• v:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Some garbled attempt at applying properties of lenses, images, and linear magnification.
• x:
  Implementation/application of ideas, but credit given for effort rather than merit. No clear attempt at applying properties of lenses, images, and angular magnification.
• y:
  Irrelevant discussion/effectively blank.
• z:
  Blank.
  

Grading distribution:
Sections 30882, 30883
Exam code: midterm01rx1C
p: 35 students
r: 3 students
t: 4 students
v: 1 student
x: 0 students
y: 0 students
z: 0 student

A sample "p" response (from student 9490), solving the thin lens equations:
Another sample "p" response (from student 1337), using ray tracings:
Another sample "p" response (from student 5504), using both thin lens equations and ray tracings:

Physics midterm question: largest possible diverging lens image

Physics 205B Midterm 1, spring semester 2016
Cuesta College, San Luis Obispo, CA

An object is allowed to be placed at any distance in front of a f = –12.0 cm diverging lens. Discuss where the object must be placed in front of the lens in order to obtain the largest image possible. Explain your reasoning by using ray tracings and/or thin lens equations, the properties of lenses, images, and magnification.

Solution and grading rubric:

• p:
  Correct. Proves that the object should be as close to the diverging lens as possible in order to obtain the largest image (largest linear magnification factor) using at least one of these methods:
  1. two or more calculations of the image distances produced by different object distances, finds the resulting respective image sizes or linear magnification factors (or one calculation is sufficient, provided discussion on how the calculation would change if the object were brought closer to the lens), and;
  2. drawing two or more carefully, properly scaled ray tracing diagrams (or one diagram is sufficient, provided discussion on how the diagram would change if the object were brought closer to the lens).
• r:
  As (p), but argument indirectly, weakly, or only by definition supports the statement to be proven, or has minor inconsistencies or loopholes.
• t:
  Nearly correct, but argument has conceptual errors, or is incomplete.
• v:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Some garbled attempt at applying properties of lenses, images, and linear magnification.
• x:
  Implementation/application of ideas, but credit given for effort rather than merit. No clear attempt at applying properties of lenses, images, and angular magnification.
• y:
  Irrelevant discussion/effectively blank.
• z:
  Blank.
  

Grading distribution:
Sections 30882, 30883
Exam code: midterm01rx1C
p: 19 students
r: 6 students
t: 9 students
v: 8 students
x: 1 student
y: 0 students
z: 0 students

A sample "p" response (from student 5433):

Physics midterm question: increasing DVD (grating) to screen distance

Physics 205B Midterm 1, spring semester 2016
Cuesta College, San Luis Obispo, CA

A red laser (wavelength 632 nm) illuminates a transparent DVD (digital videodisc) with a track spacing[*] of 740 nm, producing a central and two first maxima spots on a screen (drawing at right is not to scale). While the positions of the laser and the screen are kept constant, the DVD is moved slightly to the left, closer to the laser (and farther from the screen). Discuss why the spacing of the maxima spots as measured along the screen will change as a result. Explain your reasoning using trigonometry, the properties of source phases, path lengths, and interference.

[*] en.wikipedia.org/wiki/File:Comparison_CD_DVD_HDDVD_BD.svg

Solution and grading rubric:

• p:
  Correct. Proves that the spacing of the maxima spots on the screen would increase because:
  1. the spacing d between tracks, the wavelength λ of the laser would not be affected, such that the θ angle of the first maxima would also not be affected, and;
  2. from trigonometry (or properties of similar right triangles), as the θ angle of the first maxima remains constant, as the horizontal (adjacent) right triangle leg increases, the vertical (opposite) leg must increase.
• r:
  As (p), but argument indirectly, weakly, or only by definition supports the statement to be proven, or has minor inconsistencies or loopholes.
• t:
  Nearly correct, but argument has conceptual errors, or is incomplete.
• v:
  Limited relevant discussion of supporting evidence of at least some merit, but in an inconsistent or unclear manner. Some garbled attempt at applying trigonometry, properties of source phases, path lengths, and interference.
• x:
  Implementation/application of ideas, but credit given for effort rather than merit. No clear attempt at applying trigonometry, properties of source phases, path lengths, and interference.
• y:
  Irrelevant discussion/effectively blank.
• z:
  Blank.
  

Grading distribution:
Sections 30882, 30883
Exam code: midterm01rx1C
p: 21 students
r: 0 students
t: 11 students
v: 7 students
x: 4 students
y: 0 students
z: 0 students

A sample "p" response (from student 7399):