Monday, June 17, 2013

The Sodium Chlorate Challenge

As the third week of the short summer session for freshman electromagnetism opens, the minds of young professors everywhere run towards cool polarized light demonstrations.  In helping track some of these down, I remembered that there was an awesome experiment involving sodium chlorate in a book titled "Crystals and Crystal Growing" by Alan Holden, Phylis Morrison.  It turns out that sodium chlorate crystals pass polarized light at different angles depending on the wavelength of the light.  In short, if you place a sodium chlorate crystal between two Polaroid sheets, and then rotate one while keeping the other still, you will see the color of light passed though the crystal change, (picture1)[1].

Detail of the Experiment

Since I don't have time to grow a crystal, I thought it should be easy enough to find a video of the experiment  on the internet.  So far, I've searched to no avail though.  So, here's the challenge... Can anyone provide a video of this experiment?  Does anybody have a sodium chlorate crystal lying around they'd like to try this with?  If anybody would like to try growing a crystal, I've included the recipe below[2].  To add injury to insult, in Europe, the sale and use of sodium chlorate has been banned[3] and it appears to be somewhat hobbled here in the States where it can only be shipped to businesses and schools.

Sodium Chlorate Crystal Recipe

1.  Sodium Chlorate Polarized Light Experiment

2.  Sodium Chlorate Crystal Recipe


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