## 20160129

### Online reading assignment: total internal reflection, polarization

Physics 205B, 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 total internal reflection and polarization.

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.
"There are three cases in which light will start in a higher refractive index material: the incident angle is less than the critical angle; the incident angle is equal to the critical angle; or the incident angle is greater than the critical angle."

"For all incident angles less than the critical angle, both refraction and reflection can occur."

"A horizontal antenna works with horizontally polarized light. A vertical antenna works with vertically polarized light."

"I understood pretty much all of the basic concepts pretty well! And i really liked the applications that was shown in the blog."

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 couldn't understand how the applications work. For example, antenna and optical fibers."

"I think I will need more help on total internal reflection. I somewhat understand the equations that are shown in the pictures in the presentation but the explanations underneath confuse me. How do we know if the transmitted angle is subject to Snell's law?"

"I do not get anything on polarizers. Maybe will help if covered in class."

"The math of it all, mostly. I just need more practice, I understand the concepts pretty well."

If the incident angle of a light ray is less than the critical angle, the light ray will be:
 reflected. * [1] transmitted. *************** [15] (Both of the above choices.) ******************** [20] (Neither of the above choices.) [0] (Unsure/guessing/lost/help!) ** [2]

If the incident angle of a light ray is greater than the critical angle, the light ray will be:
 reflected. ********************************** [34] transmitted. ** [2] (Both of the above choices.) ** [2] (Neither of the above choices.) [0] (Unsure/guessing/lost/help!) [0]

Total internal reflection is possible when a light ray in a __________ medium hits a boundary with a __________ medium.
 faster; slower. ******** [8] slower; faster. ************************* [25] (Both of the above choices.) ** [2] (Unsure/guessing/lost/help!) *** [3]

A vertical antenna will emit __________ polarized light.
 horizontally. ***** [5] vertically. ********************************* [33] (Both of the above choices.) [0] (Neither of the above choices.) [0] (Unsure/guessing/lost/help!) [0]

Horizontally polarized light can be received by a _________ antenna.
 horizontal. ********************************** [34] vertical. **** [4] (Both of the above choices.) [0] (Neither of the above choices.) [0] (Unsure/guessing/lost/help!) [0]

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"I'm liking the 'preview previous blog responses' area on the website! It helps me go back and make sure I do or don't understand the material!"

"Is there any meaningful difference between the custom textbook and the original textbook?" (In terms of content, no, other than the weird double-numbering of the pages.)

"I got called into work the nights I intended to do this assignment. I'm actually at work right now."

"I'm so tired of school. All I want to do is sleep and eat without getting fat, and get really smart without trying." (#nopainnogain)

"I was rolling huge tires today in-between sprints. It was awesome. It hurts so good." (#flexfriday)

"What's your exercise of choice, other than swing dancing? Mine's running." (Mrs. P-dog and I go hiking, in order to train for backpacking or peakbagging in the Eastern Sierras.)