Cuesta College, San Luis Obispo, CA
Students have a bi-weekly online reading assignment (hosted by SurveyMonkey.com), where they answer questions based on reading their textbook, material covered in previous lectures, opinion questions, and/or asking (anonymous) questions or making (anonymous) comments. Full credit is given for completing the online reading assignment before next week's lecture, regardless if whether their answers are correct/incorrect. Selected results/questions/comments are addressed by the instructor at the start of the following lecture.
The following questions were asked on reading textbook chapters and 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.
"How to do ray tracings, but not sure what they are illustrating."
"I learned how to trace the light rays through each type of lens. I didn't understand it in class where the third line was supposed to go but I got it now."
"I understand the basics of diverging lens ray diagrams. I feel like I can successfully start to attempt these problems."
"I get that converging lenses take parallel rays of light and bring them to a focus at a point in space whereas diverging lenses take parallel rays of light, de-focuses them, and projects them outward away from a point that, when traced, ends up being in FRONT of the lens. The points (F) are FOCAL points. A real image occurs when rays of light intersect at a point in space (converging lenses). A virtual image occurs when rays do NOT intersect and move outward from an extrapolated location."
"Converging lenses causes incident parallel rays to converge at the focal point. Diverging lens causes incident parallel rays to diverge after exiting the lens. Diverging lens always forms a virtual image that is on the same side of the lens as the object and is upright and smaller relative to the object."
"A diverging lens will create a virtual image that is upright and smaller that the original."
"Lenses create images by refracting light through the lenses surfaces. Two different kinds of lenses manipulate light by either focusing beams or 'defocusing' beams of light to create an image."
"I understand that if the redirected rays of light intersect at a location beyond the lens, then the object is portraying a real image. I also understand if there is a lack of intersection beyond the lens among the redirected light rays then the image is a virtual image."
"I understand that I will have to study physics more than I am right now."
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 keep reading the presentation over and over again but can't figure out what the difference between real and virtual."
"I have go through it thoroughly yet but it is difficult to understand the way to draw a graph to find the image for a diverging lens."
"I found the ray diagrams to be a bit confusing at first but it is making much more sense now."
"I'm not quite sure when drawing ray diagrams whether a virtual or real image occurs. Are virtual images before the lens and real images after the lens? Some quick clarification would go a long way."
"I am still a little bit confused on virtual images vs real images. I'm not sure which is considered virtual or real when looking at the examples that we have on the reading assignment."
"Whether an image is real/virtual, upright/inverted, or enlarged/diminished was very confusing. The book and presentations weren't super helpful, perhaps I missed something!"
"I found converging lenses more confusing. I feel like they are much different from diverging lenses and would appreciate an introduction to these."
"I'm really confused on what a real and virtual image is. I see the definitions but I do not understand what they mean or look like."
"When is an image real or virtual? How do we determine image orientation? Those are the most confusing parts for me."
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 [55%]
Converging lens 2: real image [48%]
Converging lens 3: (no image produced) [35%]
Converging lens 4: virtual image [48%]
Converging lens 5: virtual image [42%]
Diverging lens 6: virtual image [48%]
Diverging lens 7: virtual image [39%]
Diverging lens 8: virtual image [32%]
Diverging lens 9: virtual image [45%]
Diverging lens 10: virtual image [45%]
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 [26%]
Converging lens 2: inverted, enlarged [32%]
Converging lens 3: (no image produced) [37%]
Converging lens 4: upright, enlarged [26%]
Converging lens 5: upright, enlarged [26%]
Diverging lens 6: upright, diminished [35%]
Diverging lens 7: upright, diminished [32%]
Diverging lens 8: upright, diminished [30%]
Diverging lens 9: upright, diminished [35%]
Diverging lens 10: upright, diminished [30%]
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"This is beyond me right now, I will definitely need extra help. But hopefully I'm not alone!" (You are not alone.)
"I have absolutely no idea how to distinguish between upright/inverted or diminished/enlarged images for divergent or convergent lenses. Hopefully we will go over that in class." (We certainly will.)
"I would like to know what type of lens eyeglasses are made of. So would all eyeglasses have to be a form of converging lens or diverging lens? (Yes, depending on whether you needed glasses to see near, or to see far. We'll discuss this more next week, and even find out how to calculate a prescription for glasses, without having to go to four years of optometry school.)
No comments:
Post a Comment