## 20130205

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 using ray tracings to determine the images produced by lenses.

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 fact that there can be real and virtual images."

"The insanely adorable kitten playing in front of the mirror. It makes me want to get a cat."
(That was actually a polydactyl (extra-toed) kitten.)

"Learning about lenses is interesting because many people, including myself, wear glasses and we can see why we need the types of lenses that we do."
Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.
"Ray tracing is more confusing than it looks. There seem to be quite a few rules that need to be memorized to determine how a ray will be transmitted through a lens."

"The whole virtual image thing confuses me in reference to lenses."

"I get confused about determining which lenses are convex and which ones are concave!" (Concave lenses are thin in the center, thick on the edges--imagine each side looks like a cave: )(. Convex lenses are thick in the middle, thin on the edges--each side bulges out: ().)
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"What is your favorite physics topic?" (Using x-rays to make holograms of atoms and atomic structures..)

"How do they make holograms like Tupac at the Coachella Music Festival?" (No actual holography was involved, merely a virtual image produced by partially reflective mirrors.)