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 re-reading textbook chapters and reviewing presentations on 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.
"Polarization has been easier to understand from the presentation and in class activities. Based on the way the antenna or whatever transmission device is facing, polarization will occur neither above or below, but alongside it."
"In all honesty I found this material unclear without an instructor's explanation. Extra help and clarification is needed."
"The lesson was pretty easy to understand regarding the function of antennas and their waves. The use of vertical and horizontal antennas have different uses such as for airplanes or old fashion televisions."
"The fence model example to describe polarization is VERY helpful. Makes the concept easy to imagine/see."
"Only about half of the original intensity of unpolarized light is able to pass through a polarizer. Meanwhile the remaining light is vertically polarized with another half of polarized light."
"Light polarization can be studied through interaction between antennae and polarizers. Light emitting from a glowing phenomenon, like molten lava, is unpolarized--oscillating in all directions, whereas an antenna is polarized (vertical waves). Incident light polarization can be calculated by the angular orientation of the polarizer. A polarizer set perpendicular to the wave will have a transmission of zero, as cosine2(90°) is zero. Incident light from a vertical antenna passing through a vertically-oriented polarizer will have essentially full transmission (cosine2(0°))."
"The introduction to polarization in general terms. I understand antennas much better as far as knowing what direction they should be for signal reception."
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.
"Polarization is confusing in my opinion. I feel with some extra explanation I'll understand."
"Malus' law is confusing. Especially when the transmission axis polarizer is at arbitrary angle to the polarization of incident light."
"Thinking through the specific polarization(s) of light that would be blocked."
"I feel as though I understand most of this material. But I could use some better explanation on how the angle of unpolarized light going through a polarized surface, how you are able to calculate the amount of light making it through."
"Double layers of polarization."
"I had a little more difficulty understanding the fencepost model. Specifically the relationship between the direction of light and the fenceposts."
0%. ****** [6] 50%. ********************** [22] 100%. * [1] (Unsure/guessing/lost/help!) ** [2]
Unpolarized light shines through two ideal polarizing sheets, that have their transmission axes aligned at right angles to each other. How much of the original intensity is transmitted through these two sheets?
0%. ******************** [20] 50%. ******* [7] 100%. * [1] (Unsure/guessing/lost/help!) *** [3]
When the light that passed through the first polarizer is now completely blocked by the second polarizer, the transmission axis of the second polarizer is:
horizontal. ******* [7] vertical. ********** [20] diagonal, upper left to lower right. [0] diagonal, lower left to upper right. * [1] (Unsure/guessing/lost/help!) *** [3]
Light from the screen of the iPad (in portrait mode) is:
horizontally polarized. ******************* [19] vertically polarized. *********** [11] diagonally (upper left to lower right) polarized. [0] diagonally (lower left to upper right) polarized. [0] unpolarized. * [1] (Unsure/guessing/lost/help!) [0]
Light from the screen of the Nexus 4 is:
horizontally polarized. *** [3] vertically polarized. ********* [9] diagonally (upper left to lower right) polarized. **** [4] diagonally (lower left to upper right) polarized. *********** [11] unpolarized. ** [2] (Unsure/guessing/lost/help!) ** [2]
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"Would radio waves be blocked better by some building materials than others?" (Yes, if an insulating material is really thick, or by a thin layer of conducting material (which is a better receiver of radio waves, and so would "subtract" out radio waves.)
"Not sure I understand when light passes through the first polarizer and get blocked by the second one."
"I'm good as long as we go over polarizers in detail."
"Could you go over Malus' law and the last part of the polarization section of the presentation preview?"
"Polarizing directions are confusing."
"Coming to office hours when I am too confused really helps."
"I am really glad that you are instructing our lab sessions. I feel much more secure in class."
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