dan lasota's masters in education portfolio for online innovation and design


Olive Oil and Verdet

31 March 2015 project

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:

Media Verdet Constant
(radian/Tesla meter)
BK7 Glass ~6
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.

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