Online reading assignment: Kirchhoff's laws (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 Kirchhoff's laws.

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.
"The Doppler effect; I like cars but I never really think about the fact that a car sounds different coming as opposed to driving away from you."

"How astronomers can tell if stars are moving towards us or away from us by using their absorption spectra."

"'Tasting the rainbow,' because we can find a lot of information if we understand about certain colors of the spectrum."

"The Doppler effect, since it's hard to understand why the sound would be pitched differently without knowing the science behind it."

"That there is an actual scientific reason for things I never even realized (the car making that certain noise as it goes past)."

"I found this statement from the textbook: 'If light did not interact with matter, you would not be able to see these words, in fact, you would not exist,' which right away is crazy to wrap your head around that concept. Light and matter interacting is what makes up everything; on an even smaller scale the electrons within the atoms that make up matter and how their speed, motion, and direction is what produces such."

"Learning about the different types of spectra was interesting. It's also nice to have photos for them so we could understand better."

"Redshifts and blueshifts--I thought the example used with the car and the squishing and stretching helped me understand the concept better. I thought this was interesting because it is something I have noticed but never known what it was."

"How things appear different depending on its temperature."

"That bar codes actually contain some information as to what or here the product comes from. Also, the 'neeeeeoooowww' is interesting when it comes to how different they are depending what direction the car is moving."

"Comparing absorption spectra to bar codes was interesting, because it helped me better understand the concept."

"The Doppler effect was interesting since I saw it in a new view related to wavelengths rather than through physics."

"I didn't previously understand the Doppler effect or anything relating to it, but I have a way better understanding of it now, and wavelengths. It's interesting learning things you don't know because now you know it."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"Nothing was too confusing in this section."

"Why is towards called 'blueshift,' and away called 'redshift?'"

"Figuring out which spectra associates with which source. It would be easier if the blog gave answers to the questions to see if we were right at identifying them."

"How sound waves from the car horn become 'squished' or 'stretched,' because I'm not exactly sure how the sound waves become this way."

"The Doppler effect. I don't understand how the the apparent change in the wavelength of radiation is caused by relative motion of a source and observer."

"I found the different spectra to be confusing because I cannot seem to identify the real world applications."

"I found the absorbtion/continuous/emission spectra confusing and had to keep referring back to the textbook to understand it."

"I found it confusing to figure out how to tell if the pictures you gave us were absorption, emission, or continuous spectra"

"I honestly didn't find much confusing about these chapters. I've worked with the color spectrum a few times before."

"I'm a little confused on the blue and red shifts (which are either caused by a velocity approach or a velocity of recession) but the amount of the alterations in the wavelengths depends on the source. I just wanted more clarification on that and an example because I'm confused on how a wavelength would particularly change. How were spectral lines made to measure these changes?"

"The continuous, emission, and absorption spectra were somewhat difficult to understand because of the little detail of explanation in the book."

"Nothing was confusing."

"I am still a bit confused on how to tell from the different spectra. The visuals and explanations didn't quite make sense to me."

"How atoms in stars' atmospheres absorb photons."

"All of it. Mainly the spectra stuff."

"Something I found confusing was if an object is hot and dense, if its spectrum is absorption or emission."

"Absorption spectra, because I did not understand why certain colors are missing from an overall rainbow."

"The difference between blueshift and redshifts."

"Kirchhoff's Laws were confusing just because I was getting them mixed up."

I believe Pluto should be a planet.
Strongly disagree.  [6]
Disagree.  [14]
Neutral.  [10]
Agree.  [11]
Strongly Agree.  [4]

Briefly explain your answer to the previous question (whether Pluto should be a planet).
"It doesn't match the criteria for a planet as set by astronomers."

"Planets are defined by the rules that categorize them, the rules have changed to exclude Pluto."

"It passes all the requirements: rounded shape, orbits the sun, cleared it's surroundings of debris."

"Because it qualifies. It has a rounded shape, orbits the sun, and has cleared it's orbit of debris like asteroids."

"I just don't really care."

"Because I grew up thinking Pluto is a planet, but now it's not. Scientifically that's correct, but personally we all need a Pluto in our lives."

"I want Pluto to be a planet, but I understand that Pluto should not be a planet because of the requirements that have been established. It does not dominate its own orbit, and therefore cannot be classified as a planet."

"I'm neutral because I believe that Pluto is technically not a planet but that it should just be considered one for old times' sake."

"Because it is round like all the other planets and it circles the sun."

"If you follow the guidelines to be a planet, Pluto does not follow all of them."

"Pluto will always be a planet in my heart, but I can understand why it's not classified as one. It doesn't dominate its orbit, unlike all the other planets."

"After learning about the actual qualifications of planets, Pluto is technically not a planet."

"I still think Pluto should be a planet just because it qualified as a planet when I was younger. I don't really care that they changed the definition of a planet."

"Though Pluto orbits the sun and is round in shape, it is simply too small to dominate its orbit and therefore is a dwarf planet."

"It's just not fair"

"I love Pluto, it was once a planet and I don't agree with them taking that away."

"I still think that if researchers say it's not a planet, then it's definitely not a planet."

"I think as we discover more and are constantly learning and adapting and since Pluto is actually a dwarf planet, I think that is what it should be recognized as."

"Pluto is a dog, not a planet!"

"Even though its small it still orbits the sun. Why wouldn't it be a planet? I personally think that it's a little rude to exclude pluto because of his size."

"We learned about the different requirements a planet has to have to be called one, and Pluto doesn't satisfy all of them."

"It does not meet the qualifications to be a planet."

"No, because it no longer fits the description of what a planet is."

"I think Pluto should be considered a planet because it was classified as one for so long before."

"Are you asking this a second time or am I doing the wrong homework?"

"It doesn't matter to me. If I want Pluto to be a planet I'll make it one in my world."

"I think Pluto should be a planet because it's what we have always learned. At least my generation. To me, it's the same as changing a letter in the alphabet. Just because someone said that letter isn't a letter anymore. That may not be a legit example but it's how I feel"

"Pluto still does not fit under the guidelines that make up a planet, unless we want to include others into the planet catagory than Pluto doesn't fit either."

"The line for the rules have to be drawn somewhere. Some will win and some will lose."

"I believe Pluto should not be a planet because it is too far away and too small to be one."

"I grew up thinking pluto was a planet and all of the sudden its not? No 'take backsies,' people."

"It orbits the sun, it's cool, it's red, and it was a planet when I was a kid. 3/15/2016 10:55 AM View respondent's answers"

"Pluto and I used to best friends until he took my prized pig to the county fair. Once he won the blue ribbon he married my wife and took my job. I was forced into the streets where I met a kung fu master. He taught me the art of karate (oddly enough since he was a kung fu master). I then challenged Pluto to a fight which I won. Pluto used to be much bigger until I round-house kicked him into what is now known to be the Kuiper belt. That is why he can't dominate his orbit and can't be a planet."

"It was a planet for a long time."

"I actually still don't know how I feel about it."

"I know that the laws have been changed regarding what classifies as a planet, but its rude to revoke Pluto's membership!"

"I think Pluto should probably still be a planet because it's just kind of rude to classify something as a planet one day and change your mind the next day because its small (a dwarf planet)."

"Pluto was once a planet, once deemed a planet it shouldn't change."

"I strongly disagree that Pluto should be a planet because it does not follow the three requirements to be a planet. It does orbit the sun and is round-shaped, but unfortunately Pluto does not dominate its own orbit, therefore, making it a dwarf planet."

"As I said before, Pluto has always been a planet to me and I will continue to see it that way even if that means going against science!"

Match the spectrum type with their appearance.
(Only correct responses shown.)
Rainbow containing all colors: continuous [91%]
Rainbow with thin black lines: absorption [89%]
Colored lines on a black background: emission [86%]
Given off by hot, dense object: continuous [80%]
Given off by hot, diffuse gas atoms: emission [81%]
Passing through cool, diffuse gas atoms: [72%]

Hot, molten metal produces a __________ spectrum, which appears as a:
continuous; rainbow.  ************************ [24]
emission; series of bright lines on a dark background.  *********** [11]
absorption; series of dark lines on a rainbow background.  ********* [9]
(Unsure/guessing/lost/help!)  * [1]

The sun produces a __________ spectrum, which appears as a:
continuous; rainbow.  ******** [8]
emission; series of bright lines on a dark background.  ************* [13]
absorption; series of dark lines on a rainbow background.  ********************** [22]
(Unsure/guessing/lost/help!)  ** [2]

The lights atop the Fremont Theater in San Luis Obispo, CA, produces a __________ spectrum, which appears as a:
continuous; rainbow.  ************* [13]
emission; series of bright lines on a dark background.  ************************** [26]
absorption; series of dark lines on a rainbow background.  **** [4]
(Unsure/guessing/lost/help!)  ** [2]

Your instructor produces a __________ spectrum, which appears as a:
continuous; rainbow.  **************** [16]
emission; series of bright lines on a dark background.  **************** [16]
absorption; series of dark lines on a rainbow background.  ********* [9]
(Unsure/guessing/lost/help!)  **** [4]

The balrog from The Lord Of The Rings: The Fellowship Of The Ring produces a __________ spectrum, which appears as a:
continuous; rainbow.  *************** [15]
emission; series of bright lines on a dark background.  ******************* [19]
absorption; series of dark lines on a rainbow background.  ******** [8]
(Unsure/guessing/lost/help!)  *** [3]

Suppose you are standing on the sidewalk as a car, with its horn continuously on, passes by (video link). The loudness of the car horn:
starts loud, then gets quieter.  ****** [6]
starts quiet, then gets louder.  [0]
starts quiet, gets louder, then goes back down to quiet.  ************************************* [37]
starts loud, gets quieter, then goes back up to loud.   * [1]
(Unsure/guessing/lost/help!)  * [1]

Suppose you are standing on the sidewalk as a car, with its horn continuously on, passes by (video link, same as above). The pitch (high note/low note) of the car horn:
starts high, then drops lower.  ************************* [25]
starts low, then goes higher.  **** [4]
starts low, goes higher, then drops back down to low.  [11]
starts high, goes lower, then goes back up to high.   *** [3]
(Unsure/guessing/lost/help!)  ** [2]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"How do the car horn sounds relate to astronomy?

"What makes the sound waves get squished and stretched from the moving car? Why aren't the waves equal in front of the car and the back of the car?" (As they come off the front of the car, the sound waves from the horn are barely keeping ahead of the car as they both move in the forward direction, so as a result they get 'squished' (it's easier to see this in the GIF animation. As they come off the back of the car, the sound waves are moving away from the car, being left behind as the car keeps moving forward, so the waves get 'stretched.')

"Is there an easier way to differentiate between the different spectra types?" (No, y kind of just have to deal with it. But there's only three different types.)

"In an absorption spectrum, why does the energy absorbed and then sent out not show up in other places as brighter lines? I see why the dark lines are there, but when it gets sent back out it should show up as bright lines as well?" (Yes, but the bright line spectrum is sent back out in all directions, not necessarily in the same original direction that you're looking.)

"Does Cuesta have a telescope that allows us to look at the sun? (Yes, and weather permitting, we'll be able to see a very tiny Mercury pass in front of the sun on the morning of May 9 this semester.)

"Will we get to see our total grade (so far) anytime soon? (Yes, they're posted and updated after each midterm. We'll discuss this in class tonight.)

"If I try to click on a link for homework for the wrong week it wont work right? Like the only live link is the one for the current week?" (Yes, only the current online reading assignment link should be active. If not, then e-mail me right away.)

"Can we watch a movie?" (Yes. Bonus: extra-credit points.)

"How can you not love The Big Bang Theory?!?" (The Big Bang Theory makes fun of nerds and geeks to be laughed at. Shows like Community has fun with nerds and geeks to be laughed with.)

"Can I please retake the midterm :(" (Only if you first build a time machine.)

Do you think Pluto should be a planet?" (No. Because life isn't fair. Didn't we already talk about this on the first day of class?)

"Astronomy is a fun and exciting class! :^)"

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