Copasetic Flow

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...

On the Rockmite yahoo group today, Chuck Carpenter, W5USJ posted a very nice explanation of series vs. paralel resonant crystals along with a link to a FAQ on crystal oscillator design at: http://www.foxonline.com/techfaqs_cry.htm#a4 Chuck' post follows: RMers, Here's some info sent to me by Rich at ESS. Chuck, The group that requested 7114 requested it in Series Resonant crystal. Most of the other crystals that I sell are Parallel Resonant. I have included an explanation from Fox Crystal Co. web site. They are not my supplier but the information applies to all crystals and their manufacturers. This should get you where you want to be. The information that everyone needs to know is #6. 4 and 5 will help people make a circuit oscillate where they want it. This is from: http://www.foxonline.com/techfaqs_cry.htm#a4 More information can be found at: http://www.oscilent.com/spec_pages/PNDescrpt/Load_Cap.htm 4. The load capacitance (CL) of my parallel resonant crystal is rated at 20...

Photo Credit I'm exploring piezoelectric cyrstals, (crystals that produce a small electric potential when mechanically strained). I stumbled across a great concise history [pdf]. The outline is shown below. I also found an interesting summary of another amateur's experiments