http://www.physicscentral.com/experiment/askaphysicist/physics-answer.cfm?uid=20111017091810 http://www.physicscentral.com/experiment/askaphysicist/physi... (I

http://www.physicscentral.com/experiment/askaphysicist/physics-answer.cfm?uid=20111017091810 http://www.physicscentral.com/experiment/askaphysicist/physi... (I refer you to the photos there, which I think are what you want. I haven't read the text.)