20130219

Online reading assignment: magnifiers, microscopes, telescopes

Physics 205B, spring semester 2013
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 magnifiers and microscopes and telescopes.

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.
"Angular magnification, because I was unaware that is was the ratio of the near point to focal length."

"Increasing the angular size increases the magnification."

"How magnifying lens don't really magnify, they just bring things into focus. I guess that makes sense when people use a magnifying glass to focus the sun."

"Images at infinity."

"How the telescope uses angular magnification to enlarge objects and the microscope as well, but with two lenses can magnify something up to 2000 times as much. I remember having a little telescope and microscope combination pen that could do both. It was a lot of fun. With the microscope piece I could look at comics in the newspaper and see the little dots that made up the color and how they mixed different dots to make different colors."

"How similar the structure of a microscope and telescope are; with just slight differences in focal lengths to change how we see through each."

"I found telescopes and microscopes interesting because they can make objects appear really close to the naked eye and because of that they have contributed to a lot of discoveries over the centuries. I learned that the objective lens creates an image, then this image becomes the object for the eyepiece."

"How there are only two lenses in a telescope--I thought that there would be more."
Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"The magnification process was a little confusing. I wasn't really sure if anything was being magnified."

"How is it that magnifying lenses 'don't actually magnify?'"

"The different barrel lengths and lens focal lengths for microscopes and telescopes."

"The ray tracing for a telescope seems confusing."

"Angular magnification is confusing to me. I am not sure exactly what its purpose is. I am also curious why the angles have to be in radians, when most physics is done in degrees."

"Objective and eyepiece lenses--and what happens between them is a little weird."
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"When would it be a good time to go to your office, not during office hours?" (I usually stick around for 10-15 minutes after class, especially on Wednesdays. Otherwise e-mail me to arrange an appointment for times other than immediately after class, and regularly scheduled office hours.)

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