I remember this physics experiment from school and was wondering if
any physics teachers here might do it as part of their school
curriculum. If so, I'd like to offer a free license to a long exposure
software application I've written in exchange for a long exposure pic
of the experiment.
The software is called Exposure (imaginative, I know) and can be found
at http://www.nimisis.com/projects/exposure.php
A reasonably good webcam is required to use it.
Please get in touch if you're interested.