| 0- 8.0 : | * [low = 0.5] |
| 8.5-16.0 : | ******* |
| 16.5-24.0 : | ******** [mean = 22.5 +/- 9.9] |
| 24.5-32.0 : | ***** |
| 32.5-40.0 : | ****** [high = 40.0] |
| 0- 8.0 : | ** [low = 8.0] |
| 8.5-16.0 : | ****** |
| 16.5-24.0 : | *************** [mean = 24.0 +/- 9.3] |
| 24.5-32.0 : | ******** |
| 32.5-40.0 : | ********** [high = 40.0] |
| 0- 6 : | |
| 7-12 : | *** [low = 7] |
| 13-18 : | ***** |
| 19-24 : | ********************* [mean = 21.5 +/- 5.2] |
| 25-30 : | ****** [high = 30] |
"Magnifiers make objects appear bigger than they are by increasing the angular size of an object. An object that is farther away appears smaller because the angular size is smaller."
"From this section I learned that telescopes and microscopes have a different set of lenses in order to either magnify an object that is small or an object that is far away. The different lenses in both of the instruments allow each to provide different functions."
"Ray tracings for both microscopes and telescopes create real intermediate images because the rays actually converge. I am beginning to understand that placing the object just outside the focal point of the objective will result in an enlarged image."
"Microscopes use two converging lenses to zoom in on objects that are very small. The first lens, or the objective, creates a real, enlarged image in front of the second lens. This image is then used as the object for the eyepiece, which translates to an upright, virtual view of the original object."
"During microscope magnification, the focal length of the objective lens is decreased and the focal length of the eyepiece is also decreased. Conversely, in telescope magnification, the focal length of the objective lens is increased while the focal length of the eyepiece lens in decreased."
"I understand how a microscope works before reading the text since I had to understand it for biology but now I did learn about the equation for it. I didn't know that it even had an equation before so it was interesting to learn."
"The objective makes an image just inside the eyepiece focal length. The eyepiece projects this first image to an infinite distance so a relaxed eye can see the final image."
"In a compound microscope or telescope, the angular magnification is the angular size of the final image divided by the reference angular size. A difference between them is that the image in a telescope is first diminished before being magnified while a compound microscope enlarges twice."
"I now understand how a compound microscope is designed to work, something I have never thought about before in all of my years of using them in school. They work by having an additional converging lens (objective) 'pre-magnify' the image before it passes through the magnifying glass (eyepiece), ultimately increasing the angular magnification."
"I understand the microscope parts because of taking biology. I understand that the 'tube length' for microscopes is defined as the distance measured between the objective and eyepiece focal points. the 'barrel length' for telescopes is defined as the distance measured between the objective to the eyepiece lenses, which is the same as the sum of their focal points."
"Microscopes and telescopes have some similarities such as the placement of an objective at the front leading to an eyepiece in the back. Moreover, both instruments create the same ray tracing. The main difference between these two instruments is the location of the physical object. For example, the object for a microscope is located just outside of the focal point of the objective while the telescope showcases an object extremely far away."
"There is a negative sign in both the microscope and telescope magnification equations. The negative sign for both denotes that the image produced will be inverted."
"I don't quite know why but memorizing the ray tracings is still a little difficult."
"I would like a little more information on these ray tracings and how to memorize the differences from the ones we've previously done."
"I do not understand how to draw a telescope ray tracing. I also do not understand why when talking about magnification, that only focal distance is taken into consideration."
"I found confusing the formulas used to calculate the magnifications. Each formula was different depending on the optical instrument."
"I do not fully understand the ray tracings behind the microscope and telescope concepts. I am also unsure how to utilize the equations."
"I would like to go over the angular magnification equations in class. I am a little bit confused about why the magnification factors are negative, primarily."
"I'm not really confused on anything because there wasn't much in the reading, which is what usually confuses me but telescope and microscope are similar. The equations are also distinct enough not to get them confused."
"I believe I understood this topic."
Microscope objective: converging [94%]
Microscope eyepiece: converging [71%]
Telescope objective: converging [79%]
Telescope eyepiece: converging [59%]
Microscope objective: ray tracing 2 [74%]
Microscope eyepiece: ray tracing 3 (or 4) [44%]
Telescope objective: ray tracing 3 (reversed) [0%]
Telescope eyepiece: ray tracing 3 (or 4) [44%]
short; short. *************** [15] short; long. ************** [14] long; short. * [1] long; long. [0] (Unsure/lost/guessing/help!) **** [4]
short; short. [0] short; long. ** [2] long; short. ********************** [22] long; long. ****** [6] (Unsure/lost/guessing/help!) **** [4]
"A little extra help with these two-part ray tracings would be awesome!"
"Please explain the initial and final images produced by a microscope."
"May we review how to compare real-life examples to ray tracings?"
"Can we review how to actually use the equations for the magnification of the microscope and telescope please?"
"Cool concepts, but a tad difficult."
"Why are we learning about microscopes and telescopes?" (We're just finishing up the optics section of this course with some cool stuff.)
"Why can't we use the same angular magnification formula for both the microscope and telescope?" (Even though both the microscope and telescope use an eyepiece the same way (to magnify the images made but the objective lenses), the objective lens for a microscope looks at an object very close to it, just outside its focal point, while the objective lens for a telescope looks at an object very far away, essentially out at infinity. So the differences between the microscope and telescope equations object distances primarily result from the different uses of the objective lenses.)
"When looking at the ray tracing, the ray tracing to the eyepiece looks like converging lens tracing #3. However, the rays never intersect on this ray tracing. How is this possible?" (Your relaxed eye is set to look at things infinitely far away. The rays from an object at infinity are parallel as they hit your eye. So an eyepiece will take an object at its focal point and its rays will be parallel (which would normally not produce an image), but your eye will take those parallel rays as something it thinks is infinitely far away, and easily focus those rays to interpret it as being from a distant location (but apparently with a very large angular size.)
"The progression of ideas and theories and how astronomers figured them out through time."
"The different ancient astronomers' ideas about how the universe worked was very interesting, how some were based on science but some were completely not science-based, but were still believed since they were based on first principles."
"I enjoyed reading about the history of each of the early astronomers and the contributions they made to helping demystify the universe. It was interesting to me personally because I am a storyteller, so hearing peoples stories is far more engaging for me than reading the theories."
"I found it interesting that all the astronomers were a part of the Renaissance. We typically look at the Renaissance as a time of art, but it also was a time for questioning the foundation of what we had."
"The way planets orbit and how Kepler and Newton managed to figure out how and why planets move in certain way, and why planetary motion could tell us do much about the laws of the gravity apply to Earth folks and the notion of outer space. "
"I found Newton's laws and Kepler's laws to be very interesting. I think it is crazy how they came up with all these theories regarding the planets and motion."
"I found the history of astronomy interesting, because it makes it more applicable to everyday life. A lot of times learning about science makes it seem like the scientists who discovered what we know today were less human because of all the things they discovered. But reading about how long it took and how many revisions it took for astronomers to get it right, makes it easier to follow."
"Kepler's second and third laws, it reminded me of how when I play video games like Mario Cart I try to find the closest spot to the inner track so that I can take the fastest route."
"The visuals for Kepler's laws, because the orbit of the plants seemed random before I took this class."
"Galileo's observation that added to the understanding of Earth's revolution is interesting. The fact that other planets like Venus and Jupiter go around the sun aids in the understanding that Earth can revolve around the sun without losing the moon as well."
"That basically everything I had known about Galileo was wrong. He wasn't the first person to invent or even use a telescope. He just built it himself, and got credit for it."
"That before the technology like telescopes and cameras, astronomers dedicated their lives to studying and tracking the motion of the plants with just their naked eye. It is incredible to think about how much work was necessary to understand what we do now, and more so how the studies were so in-depth that the teachings were passed through lifetimes, such as Kepler picking up where Tycho left off."
"When an object orbits earth, it's like they are constantly falling around Earth because Earth's gravity is pulling them in, but they are traveling fast enough to not fall into the ground."
"Learning about telescopes from the textbook. I own a telescope and have always been interested in them and wanted to know how they worked and how you use them. And learning about the different pieces and how they are used and what they are used for was very helpful. Learning about the mirrors, the way light reflects and the primary lens was very helpful and I can apply that in my life which is great for me."
"I thought learning about how telescopes work was interesting. Like how, rather then just zooming into the sky, it captures light."
"One of the many things I personally found interesting was that magnifying power isn't as important as I thought it was for telescopes. I believed that magnifying power was very important because of the close view we got to see when seeing the moon through the telescope."
"It was interesting learning what to look for when picking out a telescope. I always thought the bigger the telescope the better, but it's more like the bigger the primary lens or mirror the better."
"Retrograde motion was confusing for me."
"I find the history portion of this week's readings a little confusing because history is not my best subject."
"I think trying to remember the different ideas and models of each astronomer and also how others incorporated or used the ideas of others and formed their own work out of it will be something that I need to focus and study on."
"I had a very difficult time understanding the theories and laws. For instance Kepler's laws: ellipses, semi-major axes and eccentricities--I couldn't begin to explain what those are about. It has to do with how I learn, I have a difficult time understanding concepts like this just by reading them. I need them explained, broken down, pictures, example, etc."
"Kepler's laws and how they work."
"I found Kepler's second law confusing. I read the explanation in both the book and online presentation and I'm still not quite getting it. I feel like I almost understand, but not enough to explain it to someone else."
"I think I am struggling most with grasping Kepler's second and third laws. My understandings from the text itself are very vague, but I am hoping the topic will be clarified during lecture or in assignments. The diagrams for the first law helped me understand better, so not having visuals for the second and third are what I believe is causing me confusion."
"Newton's cannon kind of confused me, like the paths the cannonball takes."
"The electromagnetic spectrum a bit confusing. It is just very hard for me to conceptualize everything and understand the vocabulary terms."
"I feel like I will struggle to remember everything about the telescopes."
"The telescope stuff! So much terminology and it's hard just reading straight from the book, without being able to visualize it in person."
"I'm having a hard time understanding all of the parts of a telescope and how they work together so we can see a magnified version of a far away object. I'm sure once we're in class and actually using telescopes I'll understand them because I'm more of a kinetic learner."
"I don't really understand the difference between D, fprimary, and feyepiece. They all seem pretty similar to me and I get a little confused trying to figure out which is which."
"I didn't find anything confusing, I actually understood the chapters."
"There wasn’t anything confusing to me."
"I will read it all tomorrow before class."
east to west. ***************** [17] west to east. *********** [11] (Unsure/lost/guessing/help!) ******* [7]
east to west. ********** [10] west to east. **************** [16] (Unsure/lost/guessing/help!) ********* [9]
Kepler's first law: describes the shape of a planet's orbit. [80%]
Kepler's second law: describes the speed of a planet along its orbit. [77%]
Kepler's third law: describes the speed of a planet along its orbit. [51%]
Newton's first law: relates forces with changes in motion. [57%]
Newton's second law: relates forces with changes in motion. [69%]
Newton's third law: describes a property of forces. [63%]
light-gathering: diameter of the primary lens/mirror [54%]
resolving: diameter of the primary lens/mirror [63%]
magnifying: both the focal lengths of the primary lens/mirror and eyepiece: [69%]
brightness. *** [3] resolution. * [1] magnification. ********************** [22] (Unsure/lost/guessing/help!) ********* [9]
"Magnification is the least important feature to consider when purchasing an optical telescope because higher magnifying power does not mean that there is more detail."
"I think the magnification feature is the least important feature. The magnification feature only enlarges the images after the fact. If the telescope doesn't have good brightness or resolution feature, then dim, fuzzy pictures will be enlarged."
"Just because you make something bigger, doesn't mean that it provides a clearer picture."
"Not sure."
"Can you please explain what prograde motion is? Is it just once a planet is no longer in retrograde it goes back to prograde and does that mean it moves the normal west to east direction in the sky? Or something else?" (Yes, and Yes.)
"Why don't we feel the movement of Earth?" (You can--you would need very sensitive and/or large-scale experiments to detect Earth's motions. The sway of a long pendulum will drift over several hours, which measures the rotation of Earth about its own axis; and the directions of starlight changes slightly over many months, which measures the revolution of Earth around the sun.)
"Why can't the sun be at the center of an ellipse?" (A flattened circle would just have one "center"; but an ellipse officially has two foci, or two "centers," with the sun located at one focus (while the other focus is empty!).)
"Newton's second law: exerting a force (such as gravity) on an object (such as a planet) will change its motion. The more force you exert, then the object's motion will change more. I found this to be interesting because in sci-fi movies there's always some catastrophe happening in space and I always wonder if that was accurate or not. Is there gravity in space?" (Yes, there is gravity in space, which changes the motion of objects. If you're near a planet or a star, then the gravity will affect your motion by pulling you in, and/or forcing you into a closed/open orbit. Only if you are really far away from any planet or star will there be no gravity (or a negligible amount) to affect your motion.)
"Is a telescope's size measured by focal length or by lens diameter. The text doesn't appear to say." (Both "sizes" are important. We'll be sure to carefully distinguish between them in class.)
"Do you own a telescope at home? If so, how often do you use it?" (No, because I can use Cuesta College telescopes whenever I feel like it.)
"Struggling in this class because everything makes sense in lecture, and then nothing makes sense when I'm home...I'd benefit from reviewing things again. It's also hard to conceptualize these ideas (stars, moon phases, etc) and not be able to make it make sense in real life." (I think that's pretty normal. Just keep letting me know in these reading assignments what you're having problems with, so we can get these cleared up when we're in class. Also, email me or come into office hours if you have specific questions, and you can also drop in and see the embedded tutor at the Student Success Center.)
"I feel I can only partly understand topics through the textbook itself, and instead am relying on class lecture for clarification. Do you have any tips for reading that would help make the topics more clear?" (The textbook does make for some pretty thick reading. Don't worry if it all doesn't make sense the first time you go through it; also look at the blog presentations (which emphasize the important topics) and the quiz question packets (which are examples of what you are responsible to know for the quizzes) and then go back through the textbook chapter again. Multiple read-throughs are going to be typical for a lot of these chapters, but hopefully they will make more sense each time you go through them again. Just allow yourself time to visit the textbook multiple times.)
"Do astronomers know when precession will change the north star again and what star will be the new north star after Polaris?" (Because of precession, after Polaris, in a few thousand years Gamma Cephei will be the next official north star.)
"Do you believe the Mercury retrograde can affect how people act and feel?" (I'm going to defer to what my Magic 8-Ball® says.)
"I had no idea that it was the phases of the moon that primarily controls the tides. I honestly did not know how any of it worked. Will we learn more about how gravity from the sun and moon affects the tides?" (Actually that would be a very technical topic we don't have time for in this class, but the textbook gives a nice graphical summary of the concepts involved. Instead concentrate on how Newton's laws and gravity are used to explain planetary motion (although Newton's laws and gravity can be used to explain lots of other things such as tides).)
"No comment." (You just did.)
"I understood the presentation on myopia. I think it was super cool to see how we are entry-level optometrists after this."
"Refractive power is used by optometrists to measure the degree at which light is converged or diverged denoted by a (+) or (–) sign. It is also the inverse of the focal length."
"The combined total refractive power for two lenses is addition of each refractive power."
"Negative values for the focal length and refractive power mean that corrective lenses should be diverging, to correct for the person's myopia. Corrective lenses with a positive focal length and refractive power will be converging lenses, to correct for hyperopia."
"Magnifiers 'magnify' by increasing the angular size of the object thus making the object appear bigger to the eye. Increasing the distance between the object and the eye provides a smaller angular size and makes the object appear smaller."
"Angular size is the size of an object at a certain distance. The larger the object, the larger the angular size. Magnification isn't really magnifying but rather the lens allows the eye to be able to focus on the object at a distance where it other wise wouldn't have been able to."
"Corrective optics. It all seems overwhelming, but simplification will help. Especially refractive power and power addition equations."
"Still figuring out how to work with the thin-lens equations. The steps for correcting myopia and hyperopia were a little confusing."
"I am a little confused on the important difference(s) between linear and angular magnification. I think that I get the basic idea of both but want to make sure I clearly understand how they differ."
"Maybe a little more clarification on the mathematics on angular magnification."
"I did not understand how the eye can perceive the penny to be bigger than the moon. I also did not understand the idea of doing multiple thin lens equations for two lens."
"A review of the equations for angular size and angular magnification would be very helpful. Also I am not really sure about what it exactly means when 'the image is at infinity.'"
"The math seems a little confusing to me right now per usual. But it's late and I'm sleepy."
closer than. ******* [7] at the same distance as. ** [2] farther than. ********************** [22] (Unsure/lost/guessing/help!) * [1]
closer than. ************************** [26] at the same distance as. [0] farther than. ***** [5] (Unsure/lost/guessing/help!) * [1]
Glasses/contacts to correct for myopia: diverging [75%]
Glasses/contacts to correct for hyperopia: converging [78%]
Glasses/contacts to correct for presbyopia: converging [29%]
Magnifying lenses: converging [74%]
"Diopters. Refractive power is 1/f."
"The unit of refractive power for lenses is diopters, which is the inverse of the focal length."
"Units for P are meters–1."
"I don't understand what this is asking. "
"Linear magnification is 'm' and angular magnification is 'M.'"
"m is the ratio of the object's distance or height to the images distance or height at convergence of the light rays hi/ho or –di/do. M is how much the apparent size of something is change by a magnifying lens. The apparent size is an illusion and relative to the viewer."
"m is the ratio of image height to object height while M is a distinct ratio of angular size of some image produced by an optical instrument divided by the reference angular size of an object viewed without an optical instrument."
"I'm not sure what the answer is."
"Again, I am pretty lost."
"Don't remember."
+∞. ************ [12] +25 cm (at your near point). *********** [11] +f (at the focal point of the lens). **** [4] (Unsure/lost/guessing/help!) ***** [5]
increase. **************************** [28] decrease. * [1] remain unchanged. [0] (Unsure/lost/guessing/help!) *** [3]
+∞. **** [4] +25 cm (at your near point). ************* [13] +f (at the focal point of the lens). ********** [10] (Unsure/lost/guessing/help!) ***** [5]
#3. * [1] #4. *************************** [27] (Unsure/lost/guessing/help!) **** [4]
"Can you show a drawing demonstrating the difference between microscope and telescope lens placement and rays? I was confused with presbyopia and how that age-onset disorder works with myopia. (1) In that case someone would be unable to see far--myopia--while simultaneously being unable to see close--presbyopia? Also (2) can someone experience hyperopia and presbyopia or would the condition default to the latter? Finally, while partially off-topic, (3) is there a physics-based description of blindness?" ((1) Yes, someone with myopia (can see near, can't see far) who develops presbyopia (can't see near) would then require bifocals to correct both problems. (2) If you can't see near as a child, you have congenital hyperopia. If you could see near when you were young, but gradually lost that ability as you got older, then you have presbyopia, which is basically age-onset hyperopia, and they are both corrected with a (stronger) converging lens prescription. (3) Not really, I would think that's more of a biology/anatomy/physiology thing.)
"Can we go over problems or see these problems done? When I see these equations being used it makes it easier to understand."
"I have some questions about what a relaxed eye is meant to focus on."
"Please help to understand the angular size and tie all the equations to the ray tracing, this is getting complex."
"I'm not too confident on my answer for how close a simple converging lens used as a magnifier should be."
"I would love more examples of how to guess what kind of ray tracing would apply to real-life situations like a magnifier."
"I think angular magnification is the hardest part of this section, especially when comparing them to ray tracings." (It really is. More on angular magnification next week.)
"Can the human eye control the amount of light that comes in?" (It make less light come in (by making the pupil smaller, or by squinting your eyelids), but it can't make more light coming in than is already there.)
"Do you meditate? Moreover, if you do meditate, do you call it 'total internal reflection?' (Sorry I'm a couple chapters late on this joke.)" (I think my meditation chill is more like something called 'frustrated total internal reflection.' It's when total internal reflection is supposed to happen, but introducing an external object with a new index of refraction that barely touches that surface ruins the total internal reflection, allowing a transmitted ray to go through.)
"How long have you taught physics?" (My first physics class as an instructor was at UC-Davis 26 years ago, when I was still a graduate student.)
"I find the strange patterns we see in the moment of planets when viewed from an also moving Earth to be fascinating."
"That planets go through retrograde because before this class I had no idea that the planets can go the opposite way for a bit of time."
"The phases that Venus undergoes, when it's going between the sun and Earth."
"Kepler's laws and Newton's laws--I think it's interesting overall to read about how much astronomy has evolved and to learn about those who affected astronomy in large ways and how they affected science."
"Newton's cannon was super-interesting, because it could debunk the theory of flat Earth."
"What I thought was cool was learning about Galileo in this text versus in my philosophy class. I was told he invented the telescope but as I just read that is not true."
"I didn't know that light could travel through a vacuum. I thought this was interesting because I thought it would behave like sound and not be able to travel through it."
"How magnifying power was the least important power for a telescope."
"Retrograde motion and prograde motion. I just hard time remembering which one goes west and which one goes east."
"The concept of ellipses remains a bit confusing to me."
"I liked learning about telescopes, but there were some things I didn't really understand."
"How to identify whether or not a telescope was a refractor or reflector, and how to measure the fprimary, and I was wondering if that would be the same for those two types of telescopes."
"What I found a bit confusing was the types of telescopes. I think I found this confusing because there are so many new terminological definitions to remember and having to distinguish them from one another. Mainly, it's new terminology to get used to that I might have to go over more."
"Honestly, all the reading was confusing because there was a lot of info being thrown at once."
"There was no content that I found confusing from this assigned reading or presentation."
east to west. ************ [12] west to east. ********** [10] (Unsure/lost/guessing/help!) *** [3]
east to west. ************ [12] west to east. ********* [9] (Unsure/lost/guessing/help!) **** [4]
Kepler's first law: describes the shape of a planet's orbit. [88%]
Kepler's second law: describes the speed of a planet along its orbit. [80%]
Kepler's third law: describes the speed of a planet along its orbit. [56%]
Newton's first law: relates forces with changes in motion. [32%]
Newton's second law: relates forces with changes in motion. [56%]
Newton's third law: describes a property of forces. [52%]
light-gathering: diameter of the primary lens/mirror [52%]
resolving: diameter of the primary lens/mirror [64%]
magnifying: both the focal lengths of the primary lens/mirror and eyepiece: [56%]
brightness. **** [4] resolution. [0] magnification. ****************** [18] (Unsure/lost/guessing/help!) *** [3]
"Magnification will make the image larger and becomes much more faint."
"Magnification enlarges any distortions due to the telescope and atmosphere."
"Optical telescopes are meant to gather visible light, so it makes sense that brightness and resolution are needed in order to see that, I'm not sure if magnification is as important, but I'm also not 100% that my answer is correct."
"Magnification because it might make an image larger, but not clearer."
"Magnification only causes images to get large but don't give any clarity."
"Without the brightness and resolution for a telescope you will see no image, making magnification useless because their would be nothing to magnify."
"Doesn't matter how big/close you can make something if you can't see it."
"I enjoy doing the in-class activities, I feel that it will help me to improve my learning."
"Can you go over the ellipses? I was super-confused."
"Could you go over retrograde and prograde motions?"
"What are key differences between Kepler's laws and Newton's laws."
"How does gravity pull things into an orbit so it actually moves around the planet and not fall right into it?"
"This section has been rough due to the different terminology. It's hard to remember specific definitions."
"Can you clarify more about telescopes?"
"Do you personally own a telescope? (No, because I use Cuesta College telescopes whenever I feel like it.)
"Converging lenses cause light rays to converge toward a focal point, while diverging lenses cause light to diverge (spread out). Converging lenses can produce either real or virtual images, while diverging lenses can only produce virtual images. The thin lens and magnification equations help us determine the location, size, and nature of the image a lens produces."
"I understand the image tracings a little bit better. I understand how the height and what side of object the image is on effects the the orientation and size of the image. I also understand that if the lines can be traced back that makes the image virtual."
"When drawing ray tracings, rays move from left-to-right with the object located on the left of the lens. Once the tracing is complete, if it is a virtual image, then the image would be located on the left of the lens. If the image is real then the image will be located to the right of the lens."
"The magnification equation uses the ratio of image height to object height, or the negative value of image distance to object distance. Regardless of whether or not the image is enlarged or diminished, an upright image will always have a positive height value and an inverted image will have a negative height value."
"How the thin lens equation and magnification equation are derived. I understand the basics of the thin-lens and magnification formula. I understand how near point is corrected for someone who is farsighted and how the far point is corrected using a diverging lens for someone who is nearsighted."
"This section is still on converging and diverging lens, however, it talks about how cameras and eyes are similar because they are both converging lens which produce real images. Camera have a fixed focal length lens meaning on the image and object distance is the only thing influencing its equation. Eyes have fixed image length distance since the eye is constant. This means that only object distance and focal lens are then only factors that can change."
"The difference in the different 'sighted-nesses.' Myopia being nearsighted, meaning they can see things near to them better. Versus hyperopia being far-sighted meaning they can see things far to them better. I have heard of these terms before, but it is cool to know the physics behind it!"
"Real and virtual images are still giving me a little but of trouble. I am always unsure on my answers. Also comparing ray tracings was oddly difficult."
"I'm still struggling to understand how to distinguish between real/virtual, upright/inverted, and enlarged/diminished images."
"I'm still confused about what kind of image is produced through each lens, whether the image is real, virtual. I'm also not sure how to apply the thin lens equation."
"I'm still having trouble with the distinction of real image versus virtual image. Diverging lens are always virtual I believe but need more refreshing of these concepts."
"I do not understand the sign conventions for lenses, drawing ray tracings might help. The sign conventions were just given as a list in the book so it's hard to relate them to images being formed."
"How to use the thin lens and magnification equations correctly in-relation to examples. Need some example problems and discussion to process this quantitatively to the best of my ability."
Focal length: f [91%]
(Linear) magnification factor: m [89%]
Object distance: do [94%]
Object height: ho [83%]
Image distance: di [86%]
Image height: hi [94%]
Focal length: remains constant [49%]
Lens-to-film distance: changes [60%]
Focal length: changes [80%]
Lens-to-retina distance: remains constant [74%]
Lens: converging [66%] (Only converging lenses can make inverted images.)
Image: real [63%] (All inverted images are real.)
Ray tracing: 1 [46%]
Lens: diverging [43%] (Only diverging lenses can make upright, diminished images.)
Image: virtual [46%] (All upright images are virtual.)
Ray tracing: 6 [26%]
Lens: converging [60%] (Only converging lenses can make upright, enlarged images.)
Image: virtual [46%] (All upright images are virtual.)
Ray tracing: 4 [20%]
Lens: diverging [49%] (Only diverging lenses can make upright, diminished images.)
Image: virtual [49%] (All upright images are virtual.)
Ray tracing: 7, 8, 9 or 10 [31%]
Lens: converging [40%] (Only converging lenses can make inverted images.)
Image: real [40%] (All inverted images are real, as the candle is upright, and the projected image is upside-down.)
Ray tracing: 1 [11%]
Lens: diverging [51%] (Only diverging lenses can make upright, diminished images.)
Image: virtual [54%] (All upright images are virtual.)
Ray tracing: 7, 8, 9 or 10 [28%]
Lens: converging [60%] (Only converging lenses can make upright, enlarged images.)
Image: virtual [46%] (All upright images are virtual.)
Ray tracing: 5 [29%]
Lens: converging [54%] (Only converging lenses can make inverted images.)
Image: real [46%] (All inverted images are real, as the slide is upside-down, making the projected image on the wall upright.)
Ray tracing: 2 [26%]
Myopia: can see nearby objects [97%]
Hyperopia: can see distant objects [97%]
Presbyopia: can see distant objects [91%]
"Can we please go over real and virtual images again in the examples above? I wasn't sure how to identify the ray tracings."
"I really just don't understand how we can tell whether an image is produced from a converging or diverging lens. So confused!"
"I feel that I need a lot of help with the lenses and real-life examples because I feel lost."
"Is the difference between concave and convex lenses the same as the difference between converging and diverging lenses?" (Yes, exactly.)
"I'm really unsure of how to distinguish between what produces a real or virtual image just based on the object. I feel like I missed a blog presentation that explained this because I've looked through them and I can't seem to find the best resource to help me understand them. I can see on the worksheet where the light rays intersect (or don't) if they are real or virtual and also if they are upright or diminished. I just don't know how we can determine this just be knowing what object light isis passing through. Maybe I am missing something really obvious?" (We officially didn't have a super-specific reading or lecture on this, but we had a flowchart to determine whether an image or real or virtual, and this process is something we'll pick up from practice rather than from strict formal definitions.)
"I thought this chapter was very intriguing because of its relation to human anatomy."
"Is it accurate to say that you can see a real image without having to look directly through a converging lens but in order to see a virtual image you have to look through the lens that produced it?" (Yes. You can only project a real image onto a screen, as you'll be doing in lab this week. You can see both real or virtual images by looking back through the lens.)
"Interesting material, also it's just been so cold in the mornings lately!"
