Please contact the original author.

2011/02/25
The link is removed because the URL of the original author's web site is not available any more. Sorry!

However, you can find several related EJS simulations from [url=http://www.phy.ntnu.edu.tw/ntnujava/index.php?board=16.0]Electromagnetism[/url] board  (you can download EJS source or jar file).  :D