Fond out how easy to create concentric circles with EJS.
Please click "load ejs as signed applet". You will need to give permission for browser to load ejs.
And you will find out how this applet was created with EJS.
You can modify it and generate new simulation,too!

VIEW or DOWNLOAD ejs xml source
then click to translate strings for selected locale.

Press the Alt key and the left mouse button to drag the applet off the browser and onto the desktop.