dan lasota's masters in education portfolio for online innovation and design
onidan > onid
At long last I have finished the ONID program. I consider this an end of a phase, not the end of an endeavor. Now I have an additional line I can place on my resume, but more importantly I’ve picked up knowledge in design, research, and writing.
The Faraday Effect RCL is making progress. Over the summer UAF’s School of Natural Sciences was able to purchase six flint glass rods for potential use in the Physics labs. On Wednesday of this week, I was able to do some quick testing of the rod’s effectiveness as a Faraday Rotator. The rod, manufactured specifically for the purpose of being placed in a solenoid, was able to rotate the polarization angle of a red laser by about 10 degrees. I was pushing about 11 amps of current through the solenoid, about what the power supply and the coil would handle. The rotation is significant, and will be an effective demonstration in an educational lab.
Yesterday I made a presentation to a senior design class at UAF’s School of Engineering and Mines. Prof. Sunwoo Kim is leading the design class this year and thought that the automation of my Faraday Effect lab would make an excellent candidate for senior engineering undergrads to work on as a design project. They seemed interested in the project, I should hear soon if any are willing to work with my RCL concept as their capstone project.
Oh, and my project report? It’s available. Read on, and comment if you’d like.
In order to fulfil my M.Ed. requirements I’ve had to take classes, write a project overview, and of course do a project. In part, the project involves creating a web interface as a demonstration of how students would interact with the RCL.
The four web pages that I made represent what a final completed RCL would look like. Some of it right now, like the lab controls and the web cams are not connected to the lab, but they do show how such controls would fit in with supporting materials that would make an instructionally sound lab experience.
I did think it a good idea to create instructional material, and some learning activities, after all, that is the essence of instructional design. Further, the web pages are presented in their own little shell, ornamented with a web theme that would pass the muster and guidelines of official University of Alaska Fairbanks academic pages.
The theory is meant to give relevant information for the learning activities in an engaging way, the lab equipment section gives some background to the student helping them realize that they would be working with actual equipment, and the activities are meant to reinforce the ideas presented as theory and allow students to apply their learning and investigate the Faraday Effect.
So I had expected to receive a laboratory grade pice of flint glass by now that I could use as my “Faraday Rotator”. The vendor is out of stock and won’t be able to ship for weeks. I wouldn’t get it until this semester is over. My search widened to any laboratory supply company I could find. I asked Twitter, and a resource forum for Physics Instructors. No real leads.
I had an interesting conversation with a rep from a manufacturing company today, and had q quick education on all the grades of glass that one can order and get shaped into prisms and cylinders. Still, this solution would be weeks away from arriving.
On a hunch, I started looking up Verdet Table Constants, Couldn’t I just add something to water and get a good Verdet value? (I have gained some empathy with Michael Faraday, knowing he tried over 400 substances.) I soon came across a most interesting article:
Abu-Taha, M. I., Halasa, M. A., & Abu-Samreh, M. M. (2013). On the usage of the faraday effect as an authentication technique for vegetable oils. Journal of Modern Physics, 04(02), 230-235. doi:10.4236/jmp.2013.4203
The researchers were after a way to non-destructively determine if there were physical characteristics associated with various oils that would allow one to grade samples and determine authenticity. It turns out that certain oils, Olive, Almond, and Wheat, have very strong Verdet constants. Great:
|Virgin Olive Oil||~99|
|Terbium Gallium Garnet||~119|
Even more impressive, and lucky was what I found in another article, this time from some researchers from the University of Nahrain, Iraq:
Shakir, A. A., AL-Mudhafa, R. D., & Al-Dergazly, A. A. (2013). Verdet constant measurement of olive oil for magnetic field sensor. International Journal of Advances in Electrical and Electronics Engineering, 2(3), 362-368. Retrieved from http://www.sestindia.org/volume-ijaeee/
My main take away from that article was that the Verdet constant for the olive oil that the authors studied was greatest at 650 nm. This is the color of probably the most widely used type of laser. The common red laser. Sweet!
My mission over the next day or so will be to find some glassware that will contain good sources of oil (I’ll probably go with olive oil), yet allow light to travel through. Hopefully I can find the right test tube type of vessel that won’t disperse the laser too much.
Before I have the flint glass prism in hand, I’ll need to devise a way to have the students determine the amount of rotation taking place in the polarized light.
I’ve been told, that diode lasers already produce a nearly polarized light. (And are monochromatic to boot!). I had planned on purchasing some inexpensive lasers of varying frequencies. There are many options to choose from online, especially those lasers meant as being pointers. The problem is, they are all battery powered. Battery power is not an option in the lab, where the laser needs to be on for long periods of time. I wanted a laser that could be plugged into the wall.
The other factor running against a hand-held pointer type of laser is that they start to overheat, and the intensity of light varies. Again, this makes lab use impossible, especially in a situation where I needed to measure the intensity of light. Why? Well polarization.
If light that is already polarized travels through a polarizing filter at 90 degrees to its polarized angle, nearly all of its light will be attenuated, or blocked. You can see this easily by holding two pairs of polarized sunglasses up to each other and rotating one pair at right angles. The pair of lenses will become black.
The above two pictures show my lab laser and the polarizing filter. Without any other factors in play, the intensity of the laser light should dip to almost zero when the polarizer is at right angles to the incoming angle of the laser beam. What I did was slowly rotate the polarizer and note where the dips in intensity where. It turns out that they were at 0, and 180 degrees on the polarizer. I decided I needed more precise measurements to get the characteristic curve, so I measured every two degrees:
What measures the intensity of light is a photometer of some sort. It was attached to a generic input device which has a USB interface and feeds data to a program running on one of the lab computers.
The odd thing about the photometer (shown directly above), is that it was not heavy. It’s spatial positioning is very dependent on the cord attaching it to the computer. I needed something to stabilize it. Luckily for me there was some equipment from another physics lab, in the shape of a metal crown. This device was perfect for holding the photometer steady.
Below are two graphs I made from measuring every two degrees. Basically, the polarizers work best when they are at right angles to the incoming light, but also attenuate to some degree resembling a sine curve with +- 20 degrees. At all other points on the dial, the filters let all the light through. The graphs from both points on the polarizer:
This will be the key to knowing how much the incoming laser bear has been rotated. If these dips in the intensity curves have shifted, then the exact angle of rotation can be determined.
The next phase of my project is about to begin. This is where I’ll work, at the intersection of three areas: physics, web interface, and pedagogy. If you’ve read my project proposal, you’ll see that I’m creating a Remote Control Laboratory (RCL), that will demonstrate the Faraday Effect.
The major caveat being that I won’t complete the final product. What’s missing? The machine/robotic interface between a server of some sort and the lab equipment on the table. In a finished RCL, students would interact with the equipment via a browser page and be able to control various settings in the experiment including:
But in order to control the above, I’ll need a hardware interface to all of that equipment, and probably a bunch of time in a machine room to create something capable of swapping the plastic and flint glass blocks. What my project will do is take it to that point and someone else can finish that step, or I can learn how to do it.
What I will be doing is creating a web interface. This interface will be used for some helpful testers to communicate with me and “tell” me what to swap for the block media, which angle to make the polarizing filter and how much to set the solenoid current.
Along the lines of physics, I need to gather equipment and test the physical parameters of the set up. Although I am going to demonstrate the Faraday Effect, it is not practical to give students a lab exercise where they have to test 400+ objects like Michael Faraday did in 1845. I must narrow the possible combinations, let the students build upon prior knowledge, and guide them into studying the noticeable and measurable rotation of polarized light. To that end, I am aiming for the physical parameters between the Verdet constant of the block, the field strength of the magnet, and the wavelength of the light to match up to produce around a 20-30 degree rotation. Such a rotation would be easily measurable by introductory Physics students.
Finally, from the corner of pedagogy, I need to construct some lab exercises, thought provoking questions, opportunities for collaboration and reflection on the part of the students.
Fortunately I have the help of the UAF Physics department. I have been provided the use of some lab space that is otherwise only being used on two nights of the week for instruction. I’ve been given use of a lab bench and have a pile of equipment for use.
I did need to purchase some material that wasn’t readily at hand. Namely a piece of flint glass. I also decided to purchase a normal glass block and a plastic block. (Pictured above). This package arrived from a lab supply company. Damn, Where is the Flint Glass?
I can at least get started with some of the prep work on the lab equipment in anticipation of receiving the flint glass. The flint glass has the only chance of producing a noticeable rotation with the magnetic field strength and light frequency that I’ll be working with.
Since sometime this past summer (2014), my M.Ed. committee members are:
It’s difficult to get four busy people’s schedules lined up, but on January 16 I met with the committee as a whole and the members approved my project proposal for the completion of the ONID masters degree.
The next steps I have is to get an IRB waiver, negotiate access to the UAF Physics labs to work with equipment for the project, and to do a literature review of at least 25 more articles. It’s been about six months to a year since my last search and I’m curious what else has been published in the meantime. More and more RCLs seem to be coming online.
I will be posting my reviews here in a sprint, and journal progress on the project design.
My project proposal was entitled: Designing a Remote Control Laboratory to Demonstrate the Faraday Effect to Online Students.