Science Forum

eckco · Posted: Fri Jul 04, 2008 5:02 am Post subject:

1)what makes the electron beam glow and emit visible radiation in discharge tube?

2)as i read on the sit below
http://www.aip.org/history/electron/jj1897.htm
"attempts had failed when physicists tried to bend cathode rays with an electric field. Now Thomson thought of a new approach. A charged particle will normally curve as it moves through an electric field, but not if it is surrounded by a conductor (a sheath of copper, for example). Thomson suspected that the traces of gas remaining in the tube were being turned into an electrical conductor by the cathode rays themselves. To test this idea, he took great pains to extract nearly all of the gas from a tube, and found that now the cathode rays did bend in an electric field after all."
i do not understand how gas behaves as electrical conductor on interacting with cathode rays.