20160210

Online reading assignment: history of astronomy, telescope powers (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 reviewing the history of astronomy, Kepler's and Newton's laws, and telescope powers.


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.
"How Galileo found out about the moon not being perfect and having mountains and valleys, because as a kid your always told to try to find the face in the moon and come to find out it's just an illusion that these mountains and valleys make."

"Newton's laws of motion, because I have always been interested in physics."

"Learning about how the moon affects the tides was interesting because I always knew that they did, but I didn't know how (because the oceans are deeper on Earth's bulges)."

"How planets do not move around the sun in circles, but rather ellipses. It seems like a lesser-known fact that planets behave like this."

"Telescopes, because I'm excited to look into one someday and look at the stars. "that if there is no outside force, such as gravity, pushing on an object, the motion of that object will not be changed. But while gravity is in play, the motion of the object will be changed. learning about the telescope powers. I never would have guessed that magnification would be the least important but now it makes sense to me. Keplers laws interesting because of how they all tied together and made more sense once knowing how they all worked. 2/9/2016 6:37 PM View respondent's answers Observations through telescopes is interesting to me because I've never experienced viewing planets through a powerful telescope. I think I have been missing out. 2/9/2016 6:01 PM View respondent's answers how astronomers/astrologers/philosophers never cease to seek out the truth. They don't stop with someone else's explanation of a phenomenon, they try to justify it or disprove it to test its accuracy. "

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

"The umbras and preumbras and just putting yourself into perspective. I'm having a little trouble switching between seeing from the sun, Earth, the moon, etc."

"Kepler's laws, I just need more clarification."

"Retrograde and prograde was confusing, because I couldn't really find a good explanation in the book of which direction the planets move in."

"Kepler's laws explain 'how' but not 'why' planets move... Then how did he figure them out?"

"I didn't find anything confusing."

"I found the different aspects of the telescope to be confusing. I am not familiar with using telescopes."

"I think all of the contributions and timelines of astronomers is confusing, but I think I just need to go back and re-read some of the information to make stronger connections!"

"I was a little confused about the Newton's cannon thing because of why it would come back around to the top again."

"Nothing really. It was basically a big history lesson."

When a planet is undergoing retrograde motion, over several nights it moves __________ with respect to the background stars.
east to west.   **************************** [28]
west to east.   ************** [14]
(Either of the above choices is possible.)   ***** [5]
(Unsure/lost/guessing/help!)   **** [4]

When a planet is undergoing prograde motion, over several nights it moves __________ with respect to the background stars.
east to west.   ************* [13]
west to east.   ************************** [26]
(Either of the above choices is possible.)   **** [4]
(Unsure/lost/guessing/help!)   ******** [8]

Categorize each of Kepler's laws.
(Only correct responses shown.)
Kepler's first law: describes the shape of a planet's orbit. [78%]
Kepler's second law: describes the motion of a planet along its orbit. [84%]
Kepler's third law: describes the motion of a planet along its orbit. [75%]

Categorize each of Newton's laws.
(Only correct responses shown.)
Newton's first law: relates forces with changes in motion. [74%]
Newton's second law: relates forces with changes in motion. [57%]
Newton's third law: describes a property of forces. [67%]

The __________ powers of a telescope depends on the: (Only correct responses shown.)
light-gathering power: diameter of the primary lens/mirror [61%]
resolving power: diameter of the primary lens/mirror [65%]
magnifying power: both the focal lengths of the primary lens/mirror and eyepiece: [39%]

The least important feature to consider when purchasing an optical telescope is the __________ of its images.
brightness.   ****** [6]
resolution.   **** [4]
magnification.   ************************************** [38]
(Two of the above choices.)   * [1]
(Unsure/lost/guessing/help!)   ** [2]

Briefly explain your answer for the least important feature to consider when purchasing an optical telescope.
"Magnification can be bettered by acquiring a better eyepiece, but the brightness and the resolution depend on the main lens."

"Light-gathering properties and resolving power are fundamental properties of a telescope, wile magnifying power can be changed simply by changing the eyepiece."

"If the image isn't clear and well-lit to begin with, it wouldn't be worth it to magnify. They are all important, but I believe that magnification is least because you wouldn't be able to see anything without brightness and resolution."

"Magnification doesn't make things clearer, it just makes it bigger. If you have good resolution and good light then the image will already be clear so you wont necessarily need good magnification."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Newton's law fascinates me because just thinking about how an object won't move unless it is forced by something else. It will also remain stationary if there is no force exerted on it. This is the same rule for things on Earth. So what confuses me is that does this rule apply to everything. Is EVERYTHING moving in space? Are there things out there that aren't moving at all?" (Because everything is subject to each others' gravitational pull, then yes, everything is moving and having their motion affected by those gravitational forces.)

"Is it true that a large asteroid may pass close enough to Earth for us to see next month?" (Yes, according to NASA, asteroid 2013 TX68 will do so on March 5.)

"How do the online reading assignments and in-class group activities affect our grade? Will they be reflected in the online summary?" (The online reading assignments and the in-class group activities are each worth one whole letter grade; those points will be included in the total course points posted online after each midterm.)

"Can you discuss prograde and retrograde motions more please?"

"Is there another way to study than reading the textbook and your online blogs from home?" (Yes, you can go over the worksheet question packets, as many of these questions are similar to those that show up on the quizzes. The answers are not published, but you can e-mail me your answers, and I can "grade" them for you. Just don't wait until the last-minute to do so.)

"Are we going to be using telescopes? When do we get to try out the big telescope?" (Yes. Tonight!)

20160209

Physics quiz archive: electromagnetic waves, reflection/refraction

Physics 205B Quiz 1, spring semester 2016
Cuesta College, San Luis Obispo, CA
Sections 30882, 30883, version 1
Exam code: quiz01sN0w



Sections 30882, 30883 results
0- 6 :   *** [low = 6]
7-12 :   **
13-18 :   ************
19-24 :   ****************** [mean = 20.7 +/- 6.1]
25-30 :   ******** [high = 30]

Online reading assignment: history of astronomy, telescope powers (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 reviewing the history of astronomy, Kepler's and Newton's laws, and telescope powers.


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.
"Newton's cannon, because that would be pretty awesome if that was possible."

"That overall magnification is not always that important when purchasing an optical telescope. Before taking this class I would have thought that magnification would have played a much greater role in selecting a telescope."

That there seems to be two different sets of laws; one set consists of explaining the 'how' and the other set the 'why' for the motion of the planets, which is actually something I have been wondering about."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"The difference between prograde and retrograde motion."

"There is a lot of information about the telescopes so it's hard to keep track of it all in my mind."

"The three different powers that 'rate' a telescope."

"Kepler's laws were confusing. I didn't at all understand what they were."

When a planet is undergoing retrograde motion, over several nights it moves __________ with respect to the background stars.
east to west.   ***** [5]
west to east.   ******* [7]
(Either of the above choices is possible.)   ** [2]
(Unsure/lost/guessing/help!)   **** [4]

When a planet is undergoing prograde motion, over several nights it moves __________ with respect to the background stars.
east to west.   ******* [7]
west to east.   ******* [7]
(Either of the above choices is possible.)   [0]
(Unsure/lost/guessing/help!)   **** [4]

Categorize each of Kepler's laws.
(Only correct responses shown.)
Kepler's first law: describes the shape of a planet's orbit. [78%]
Kepler's second law: describes the motion of a planet along its orbit. [72%]
Kepler's third law: describes the motion of a planet along its orbit. [56%]

Categorize each of Newton's laws.
(Only correct responses shown.)
Newton's first law: relates forces with changes in motion. [61%]
Newton's second law: relates forces with changes in motion. [67%]
Newton's third law: describes a property of forces. [61%]

The __________ powers of a telescope depends on the: (Only correct responses shown.)
light-gathering power: diameter of the primary lens/mirror [39%]
resolving power: diameter of the primary lens/mirror [28%]
magnifying power: both the focal lengths of the primary lens/mirror and eyepiece: [66%]

The least important feature to consider when purchasing an optical telescope is the __________ of its images.
brightness.   *** [3]
resolution.   [0]
magnification.   ************ [12]
(Two of the above choices.)   [0]
(Unsure/lost/guessing/help!)   *** [3]

Briefly explain your answer for the least important feature to consider when purchasing an optical telescope.
"A telescope's main purpose is to pull in light and make tiny things appear brighter; therefore, light gathering and diameter of the scope are most important."

"There is no point in zooming in on something if it is dim or fuzzy."

"The least important part of the optical telescope is magnification. This is the least important because higher magnifying power doesn't always provide you with more detail."

"Brightness and resolution can't improve after buying the telescope. Magnification can be improved by buying a different eyepiece."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Will there be a study guide for the midterms?" (Yes, there will be both study guides and in-class review sessions for the midterms.)

"Will we get the chance to look through telescopes at some point during this class?" (This Thursday.)

"PLEASE EXPLAIN TELESCOPES, PLEASE." (THIS THURSDAY.)

"Can you please go over everything we were assigned to read."

"Loved the history section! Copernicus and Aristotle are supercool!"

"Since I've started taking this course, I have noticed that when the moon and stars come out, I catch myself looking up at the sky a lot trying to point different things that I have learned! Thanks! :)"

20160208

Online reading assignment: images produced by lenses, thin lens equations, cameras and eyes

Physics 205B, 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 examples of images produced by lenses, thin lens equations and camera and eyes.


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.
"I'm going to have a lot to catch up on."

"Anatomy of the eye! That's something my medical brain can wrap around."

"Thin lens ray tracings can be a simple, fast way to double-check your work while working on magnification calculations. Though only two rays are needed to find an image, three rays through the center of the lens and to each of the focal points help ensure measurements are accurate."

"In the case of a camera, focal length is fixed and image distance and object distance are inversely related. In the case of a human eyeball, image distance is fixed and focal length and object distance are directly related. The inability to focus on far away objects is called nearsightedness (myopia), and the inability to focus on near objects is called farsightedness (hyperopia, or presbyopia when it's caused by aging)."

"It was interesting how similar eyes are to the lens of cameras."

"The convention in ray tracings is for light to move from left-to-right, with the object located to the left of the lens, and the image (if real) would be located to the right of the lens. For this case the object distance do and the image distance di would both be positive. If the image is virtual, then it would be located to the left of the lens, and the image distance di would then be negative."

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 magnification equation. I don't like it one bit. Also, the concept of the ray tracings and how it reflect what I'm actually 'seeing' in everyday life aren't connecting."

"I'm having trouble differentiating between a virtual image and a real image. Also having trouble matching up the ray tracings to the examples."

"I'm confused on how to determine if an image is real or virtual and how can we determine the correct ray tracing based off the type of lens and image?"

"I didn't find that much to be confusing. I've done thin lens rays before, getting back into ray tracings and using the equations is going well."

"I don't know if I find anything confusing right now. I'll know when I show up to class."

"This stuff is all really confusing. I need some more examples on the use of the thin lens equation, but mostly I need help with ray tracings. I can do them, but I can't interpret them. HELP!"

"I keep getting the enlarged, upright, virtual and real images confused. However, everything else so far makes sense, especially the linear magnification equation."

Identify the following thin lens parameters. (Only correct responses shown.)
Focal length: f [86%]
Magnification factor: m [86%]
Object distance: do [89%]
Object height: ho [81%]
Image distance: di [81%]
Image height: hi [86%]

For a simple camera, identify which parameter(s) must change or remain constant in order to focus on different distance objects.
Focal length: remains constant [42%]
Lens-to-film distance: changes [47%]

For a model eye, identify which parameter(s) must change or remain constant in order to focus on different distance objects.
Focal length: changes [69%]
Lens-to-retina distance: remains constant [50%]

Identify the type of lens, image, and example ray tracing produced in the online reading assignment examples. (Only correct responses shown.)

Lens: converging [61%] (Only converging lenses can make inverted images.)
Image: real [50%] (All inverted images are real.)
Ray tracing: 1 [36%]

Lens: diverging [39%] (Only diverging lenses can make upright, diminished images.)
Image: virtual [42%] (All upright images are virtual.)
Ray tracing: 6 [25%]

Lens: converging [52%] (Only converging lenses can make upright, enlarged images.)
Image: virtual [36%] (All upright images are virtual.)
Ray tracing: 4 [31%]

Lens: diverging [33%] (Only diverging lenses can make upright, diminished images.)
Image: virtual [44%] (All upright images are virtual.)
Ray tracing: 7, 8, 9 or 10 [25%]

Lens: converging [31%] (Only converging lenses can make inverted images.)
Image: real [28%] (All inverted images are real, as the candle is upright, and the projected image is upside-down.)
Ray tracing: 1 [19%]

Lens: diverging [33%] (Only diverging lenses can make upright, diminished images.)
Image: virtual [33%] (All upright images are virtual.)
Ray tracing: 7, 8, 9 or 10 [22%]

Lens: converging [47%] (Only converging lenses can make upright, enlarged images.)
Image: virtual [47%] (All upright images are virtual.)
Ray tracing: 5 [25%]

Lens: converging [44%] (Only converging lenses can make inverted images.)
Image: real [39%] (All inverted images are real, as the slide is upside-down, making the projected image on the wall upright.)
Ray tracing: 2 [14%]

A person with no vision defects can see both nearby and distance objects. Identify what can be seen by a person with the following vision defects. (Only correct responses shown.)
Myopia: can see nearby objects [78%]
Hyperopia: can see distant objects [78%]
Presbyopia: can see distant objects [67%]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Will we have to memorize the rules regarding how rays behave for converging/diverging lenses (parallel ray redirects through primary F, etc.), or will that be given to us on the quiz?" (You should have them memorized! Well, if not already, then certainly in time for the quiz.)

"I feel like the more I reread this material the better I understand it, but I'm still pretty confused on the ray tracings."

"I don't understand any of this."

"As I was doing this assignment, my contacts lens were being a pain in the butt!"

"The ray tracings were easy but interpreting images to identify the lenses and positions of objects was challenging! In a fun sort of way."

"Chocolate is my best friend. I love it so much, sometimes I eat it." (Friends don't let friends eat friends.)

20160205

Online reading assignment: lenses

Physics 205B, 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 lenses.


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.
"Converging lenses focus parallel rays of light onto a central focal point, where diverging lenses spread parallel rays of light outward, or 'un-focus' them."

"Virtual images are images that are formed in locations where light does not actually reach. Light does not actually pass through the location on the other side of the mirror; it only appears to an observer as though the light is coming from this location."

"Converging lenses bring light waves into one focus point. Diverging lenses scatter light waves in outward directions. Diverging lenses produce virtual images, but some converging lenses can produce virtual lenses as well, given specific focal points and object distances."

"In a case-by-case approach, I am confident in my ability to recognize when images are real/virtual, upright/inverted, enlarged/diminished, or non-existent."

"How to connect the ray tracing lines but that is mostly it."

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.
"I found the concept of virtual images a little bit confusing. I also found it confusing how to determine the size and orientation of an image through a lens."

"Most of this."

"I am unsure what the ray going towards the 'secondary F' does to the image with a diverging lens. If a virtual image is produced when the ray going from the source to the center of the diverging lens intersects with the ray going away from the 'primary F,' then the 'secondary F' ray seems to have no purpose."


Complete the online reading assignment ray tracings as best as you can. Identify the type of image produced for each ray tracing. (Only correct responses shown.)
Converging lens 1: real image [77%]
Converging lens 2: real image [77%]
Converging lens 3: (no image produced) [44%]
Converging lens 4: virtual image [54%]
Converging lens 5: virtual image [46%]
Diverging lens 6: virtual image [46%]
Diverging lens 7: virtual image [44%]
Diverging lens 8: virtual image [36%]
Diverging lens 9: virtual image [46%]
Diverging lens 10: virtual image [44%]

Complete the online reading assignment ray tracings as best as you can. Identify the image orientation and size produced for each ray tracing. (Only correct responses shown.)
Converging lens 1: inverted, diminished [38%]
Converging lens 2: inverted, enlarged [38%]
Converging lens 3: (no image produced) [47%]
Converging lens 4: upright, enlarged [28%]
Converging lens 5: upright, enlarged [33%]
Diverging lens 6: upright, diminished [31%]
Diverging lens 7: upright, diminished [28%]
Diverging lens 8: upright, diminished [37%]
Diverging lens 9: upright, diminished [36%]
Diverging lens 10: upright, diminished [26%]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
Could you go over more of the ray tracings, that would help a lot!"

"That ray tracing worksheet made me want to crawl under my desk and cry :'("

"On the ray tracings, do you only need two lines intersecting to produce an image?" (Yes, two lines (if drawn correctly) is sufficient to locate the image, but having all three rays intersecting at the same location is good practice.)

"I'm not sure how an image is either diminished or enlarged."

"What is the difference between a real and a virtual image in the ray tracings? How do I know which is which?"

"Having a hard time visualizing what is the object is and how it is seen through the lens. More specifically I can't visualize clearly yet what my eyes would be looking at. Are my eyes on the left or right side of the drawing? Just confused at this point." (By convention light is traveling from left-to-right, so your eyes would be located on the right side, looking to the left of the page, intercepting these left-to-right traveling rays.)

20160204

Astronomy quiz question: Lyra will rise from which horizon?

Astronomy 210 Quiz 1, spring semester 2016
Cuesta College, San Luis Obispo, CA

The diagram at right shows the positions on February 14 of the constellations Cygus, Cepheus and Lyra for an observer in San Luis Obispo, CA. Ignore daylight saving time. Assume you can see stars in daylight. After setting, the constellation Lyra will eventually rise on the __________ horizon.
(A) northeast.
(B) east.
(C) southeast.
(D) southwest.
(E) west.
(F) northwest.

Correct answer (highlight to unhide): (A)

As read off from a starwheel, Lyra will be just about to set on the northwest horizon at approximately 5:00 PM on February 14. Lyra will subsequently rise approximately 1:00 AM on February 15 from the northeast horizon.

Section 30674
Exam code: quiz01n0iR
(A) : 13 students
(B) : 4 students
(C) : 1 student
(D) : 1 student
(E) : 1 student
(F) : 1 student

Success level: 62% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.67

Section 30676
Exam code: quiz01sk4r
(A) : 34 students
(B) : 6 students
(C) : 3 students
(D) : 4 students
(E) : 1 student
(F) : 5 students

Success level: 65% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.53

Astronomy quiz archive: stars/sun/seasons/moon phases

Astronomy 210 Quiz 1, fall semester 2015
Cuesta College, San Luis Obispo, CA

Section 30674, version 1
Exam code: quiz01n0iR


Section 30674
0- 8.0 :   * [low = 8]
8.5-16.0 :   *****
16.5-24.0 :   *****
24.5-32.0 :   *** [mean = 25.5 +/- 10.5]
32.5-40.0 :   ******* [high = 40]


Section 30676, version 1
Exam code: quiz01sC4r


Section 30676
0- 8.0 :   ** [low = 8]
8.5-16.0 :   *****
16.5-24.0 :   *********************
24.5-32.0 :   ************* [mean = 24.9 +/- 7.8]
32.5-40.0 :   ************ [high = 40]

20160203

Online reading assignment: eclipses, history of astronomy (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 eclipses, and an preliminary overview of the history of astronomy.


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.
"That even the slightest tilt of the moon's orbit when it is new or full is the reason that an eclipse does not occur. I was always curious as to why they were rare."

"The classifications of astronomers in history as a mover versus a disprover. The idea that some people built up ideas while others tore them down was something I hadn't really thought about before, but this is a pretty common idea."

"How so many astronomers over time came up with different theories and discover new things about the moon and stars and whatnot, and over time these have become the knowledge of astronomy today. I just love how people build on other people's findings and how that information grows."

"The next solar eclipse in the US is on my birthday next year! I think that's so cool & I definitely wanna visit Oregon to see it."

"I always thought that the lunar eclipse was seen by everyone. It was always broadcast on television around the world so I assumed that everyone could step out of their houses at night and see the eclipse. But after reading the presentation, I found out that that is not the case and not everyone is able to see it. It depends on where you are located."

"How lunar eclipses only occur during a full and solar eclipses only occur during new moon."

"Whether there is an eclipse or not, the sun is bright enough to burn your eyes and cause permanent damage. It can be misleading to constantly look for the eclipse, because all though it may be cool, there is a risk of damaging your eyesight."

"I found reading about Tycho Brahe interesting, mainly because it was fun to read about the namesake for my old dog Tycho."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"It's hard for me to remember where the sun, moon, and Earth are in relation to each other and what's blocking what during an eclipse."

"That the reason a lunar eclipse does not occur every full moon, because the orbit of the moon is the moon is usually not tilted edge-on. I found this part a little confusing because why is the moon not tilted edge-on at all times?"

"Why the moon is as red as it is during a lunar eclipse."

"The differences between types of eclipses."

"It says in the textbook that a partial lunar eclipse can occur if the moon passes a little too far to the north or south of the center of the Earth's shadow. Why is that the case? What would make the moon 'tip?'"

"Trying to remember the important astronomers and their contributions."

"All the astronomers blended together while reading the text. I found it confusing having to remember who goes with what." "

A friend of yours has a birthday on March 30. According to your starwheel, the sun would have been located in front of which zodiac sign on that date? (Ignore daylight saving time.)
Aries.  *** [3]
Taurus.  [0]
Gemini.  [1]
Cancer.  * [1]
Leo.  * [1]
Virgo.  [1]
Libra.  [0]
Scorpio.  [0]
Sagittarius.  * [1]
Capricorn.  [0]
Aquarius.  [0]
Pisces.  *************************************** [39]
(Unsure/guessing/lost/help!)  *** [3]

Match the phase of the moon during these eclipse types. (Only correct responses shown.)
Total solar eclipse: new moon [86%]
Partial solar eclipse: new moon [65%]
Annular solar eclipse: new moon [59%]
Total lunar eclipse: full moon [84%]
Partial lunar eclipse: full moon [67%]

Place these astronomers in chronological order of their historical contribution to astronomy. (Only correct responses shown.)
Aristotle [90%]
Ptolemy [84%]
Copernicus [86%]
Tycho [76%]
Kepler [63%]
Galileo [61%]
Newton [86%]

Match these terms with their descriptions. (Only correct responses shown.)
Ideas accepted as truth without further examination: first principles [84%]
Predictions that could be tested by observations: hypotheses [69%]
Universal statements of cause and effect: rational laws [86%]
Describe phenomena without explaining why it occurs: empirical laws [78%]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Can you explain more about the different types of eclipse?" (Yes. After reading some of your responses for this reading assignment, we will need to discuss this more in class.)

"How much will we have to memorize about the astronomers? And will we have to know the dates that belong to what time astronomers founded things?" (Concentrate on their contribution to understanding how and why planets move across the sky. Dates are not important; the emphasis is on the sequence of how they built upon or refuted the work of previous astronomers.)

"What is the time span of starwheels? Taking precession into the occasion, when would this starwheel become out of date and when did it become relevant (regardless of when it was produced)?" (Star chart catalogs are typically updated in print every fifty years, and those changes are only barely noticeable on the scale of your starwheel, so it should be okay to use give or take several hundred years before and after this date.)

"Have you ever been to any astronomy conventions or telescope maker conventions?" (I've presented posters and workshops at astronomy education research workshops. Which means I do research by studying you--that is, how you learn astronomy.)

"Do you believe in astrology to make predictions about your future?" (Let me consult my Mattel™ Magic 8 Ball®.)

"Why do you use SurveyMonkey instead of Google Surveys?" (At least for now, SurveyMonkey handles scheduling, filters, and question logic better than Google Surveys.)

"I have started noticing the sky more often and going outside with my starwheel. (Cool. Cool cool cool.)

What is your favorite TV show P-dog? Big Bang Theory? (Eh, I'm not a fan--Big Bang Theory shows people with autism spectrum disorders in order to make fun of them. Community shows how people with autism spectrum disorders have fun. #poppop)

20160202

Online reading assignment: eclipses, history of astronomy (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 eclipses, and an preliminary overview of the history of astronomy.


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.
"That the full moon turns red during a total lunar eclipse. I always thought it just disappeared like the sun for a total solar eclipse."

"That the moon's phase and its orbit has to be just right to cause an eclipse."

"That in ancient times astronomers and the public truly believed Earth was the center of the universe and everything else revolved around it. I find this interesting just because it's so backwards from what we know and study today that it's hard to believe people believed that at one point."

"I liked reading about the different astronomers and how they built on each other's ideas and discoveries."

"That eclipses happen and because I've never seen one."

"That Copernicus was afraid to publish his ideas because of his connection with the church."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"How the moon phases relate to solar and lunar eclipses."

"Why are there only eclipses during certain times? Why not every time there's a new or a full moon?"

"The differences between lunar and solar eclipses are a little difficult, because it takes some time and practice to distinguish the differences between the two and what constitutes each one."

"As interesting as it is I do kind of find eclipses confusing. For me its being able to look at a picture and tell which one it is. Or where the moon would be."

"That the moon can cover the sun."

"The difference between lunar and solar eclipses."

A friend of yours has a birthday on March 30. According to your starwheel, the sun would have been located in front of which zodiac sign on that date? (Ignore daylight saving time.)
Aries.  * [1]
Taurus.  [0]
Gemini.  [0]
Cancer.  [0]
Leo.  [0]
Virgo.  [0]
Libra.  [0]
Scorpio.  [0]
Sagittarius.  [0]
Capricorn.  [0]
Aquarius.  [1]
Pisces.  ************** [14]
(Unsure/guessing/lost/help!)  ** [2]

Match the phase of the moon during these eclipse types. (Only correct responses shown.)
Total solar eclipse: new moon [44%]
Partial solar eclipse: new moon [50%]
Annular solar eclipse: new moon [44%]
Total lunar eclipse: full moon [83%]
Partial lunar eclipse: full moon [56%]

Place these astronomers in chronological order of their historical contribution to astronomy. (Only correct responses shown.)
Aristotle [83%]
Ptolemy [78%]
Copernicus [83%]
Tycho [83%]
Kepler [72%]
Galileo [72%]
Newton [78%]

Match these terms with their descriptions. (Only correct responses shown.)
Ideas accepted as truth without further examination: first principles [83%]
Predictions that could be tested by observations: hypotheses [100%]
Universal statements of cause and effect: rational laws [67%]
Describe phenomena without explaining why it occurs: empirical laws [61%]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"I have always heard not to look at the sun because its brightness can burn one's eyes. The book states this as well, has it happened to someone before?" (The damage to your eyes is from ultraviolet light exposure to your cornea, as the cells on the surface your eye are getting sunburnt, and recovery from this damage depends on the frequency, intensity and length of exposure. Notable cases of extreme long-term exposure include a girl stared at the sun for 30 minutes during an eclipse, and a man who periodically gazed at the sun for religious rituals.)

Do we have to know every name of the astronomers we were assigned to read about?" (Well, maybe not just yet, but a passing familiarity will do for now. We'll go back over what they did, and how they did it, through next week.)

"What is your favorite part about teaching this class?" (This. Answering and making comments on student questions. While the course curriculum will stay the same, feedback from students is always interesting and will keep changing over the next sixty semesters until I retire.)

20160201

Online reading assignment: polarization

Physics 205B, 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 re-reading textbook chapters and reviewing presentations on polarization.


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.
"Polarizers act like a picket fence or a filtering grate for light, filtering out waves with polarizations at 90° to their axis of transmission."

"I don't understand anything on the reading! The concepts are hard for me to understand! This is my least favorite thing thus far."

"Electromagnetic waves can be either unpolarized (particles moving in random vibrations), or polarized (particles oscillating in single back-and forth motions). Radio waves from antennae are polarized transverse waves; the orientation of the antennae (horizontal or vertical) determine how these waves are transmitted and received. Light can be polarized using filters that limit/eliminate light with a certain polarization, i.e., polarized sunglasses that block out horizontally polarized light to cut glare. This filtering cuts the wave amplitude, or light intensity, by 50%. If two filters are stacked and are perpendicular to each other, the light source will not be visible, as 100% of the light will be filtered."

"Malus' Law is used to calculate the amount of polarized or unpolarized light that is transmitted through a polarizer. If vertically polarized light passes through a polarizer with a transmission axis of 30°, then the amount of light transmitted is the square of the cosine of 30°."

"I understand just enough to be really confused. Unpolarized light comes from the sun, lights bulbs, etc., and contains every possible sideways oscillation. When light is polarized only one direction (vertical, horizontal, etc.) of light passes through the polarizer, while the others are absorbed. The polarized light will have one-half the intensity of the unpolarized light."

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.
"I believe that I have this down."

"I find it all confusing. Malus' law as an equation I could plug-and-chug, but conceptually, no chance."

"More applications never hurts."

"I don't understand the way the signal transmits from an antenna. It's basic, but not basic."

"I'm not quite sure what the 'fencepost model' is."

"All visible light begins unpolarized?"

"Polarization percentages?"

"This stuff freaks me out. I don't get how unpolarized light can contain every possible sideways oscillation, or how when that light is polarized into one direction it contains one-half of the original intensity (it's one part of an infinity of parts!), or how light that is traveling in 'one direction' can have both horizontal and vertical components. This is Schrodinger's cat stuff."

This is an ideal polarizer, where exactly one-half of unpolarized light passes through.  Realistically less than half of unpolarized light will pass through a polarizer, due to absorption and scattering.
How much unpolarized light is transmitted through an ideal polarizer?
0%.  ******* [7]
50%.  ************************** [26]
100%.  **** [4]
(Unsure/guessing/lost/help!)  ** [2]

Unpolarized light shines through two ideal polarizing sheets, that have their transmission axes aligned at right angles to each other. How much of the original intensity is transmitted through these two sheets?
0%.  ************************ [24]
50%.  ****** [6]
100%.  ** [2]
(Unsure/guessing/lost/help!)  ******* [7]

Note that whatever its orientation, one-half of the original background unpolarized light always passes through the second polarizer, whether the second polarizer transmits or blocks light that passed through the first polarizer.
Unpolarized light is projected through the first (smaller) polarizer. If the transmission axis of this first polarizer is horizontal, then one-half of the unpolarized light will pass through, and the light that passes through is now horizontally polarized.

When the light that passed through the first polarizer is now completely blocked by the second polarizer, the transmission axis of the second polarizer is:

horizontal.  *** [3]
vertical.  ************************* [25]
diagonal, upper left to lower right.  **** [4]
diagonal, lower left to upper right.  ** [2]
(Unsure/guessing/lost/help!)  ***** [5]

Polarizing sunglasses are typically manufactured with a vertical transmission axis (to filter out horizontally polarized glare while fishing or driving).

Light from the screen of the iPad (in portrait mode) is:

horizontally polarized.  ************************ [24]
vertically polarized.  ********** [10]
diagonally (upper left to lower right) polarized.  * [1]
diagonally (lower left to upper right) polarized.  * [1]
unpolarized.  [0]
(Unsure/guessing/lost/help!)  *** [3]

Consider a Nexus 4 smartphone (again, held in portrait mode), and polarizing sunglasses (with a vertical transmission axis).

Light from the screen of the Nexus 4 is:

horizontally polarized.  ****** [6]
vertically polarized.  ****** [6]
diagonally (upper left to lower right) polarized.  ******* [7]
diagonally (lower left to upper right) polarized.  ************* [13]
unpolarized.  *** [3]
(Unsure/guessing/lost/help!)  **** [4]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"I am so burnt out from life that I haven't been able to engage in any of your lectures and I need to change that! #nopainnogain" (#squadgoals)

"I need to quit my job so I have more time for school, but there's nobody to replace me because everyone else at my position already quit." (#toolegittoquit)

"Help :O"

"What happens to radio waves in space? Do they orbit around Earth or go in a straight line?" (Some radio wavelengths get absorbed or internally reflected off of the ionosphere (a layer of charged particles in the upper atmosphere), but other radio wavelengths go through into space traveling at the speed of light, decreasing in intensity as they spread outwards in all directions. Some of the signals have already traveled to nearby stars.)